solitary experiments biology

Top 30 Biology Experiments for High-School

The field of biology offers a wide range of fascinating experiments that can deepen our understanding of the living world around us. From studying the behavior of cells to investigating the intricacies of ecosystems, biologists use a variety of methods to uncover the secrets of life.

We’ve compiled a captivating list of 30 biology experiments that are both educational and fun and also suitable for a wide range of ages.

These hands-on educational activities will not only deepen your appreciation for the intricacies of life but also fuel your curiosity and passion for scientific exploration.

So, roll up your sleeves, gather your lab equipment, and prepare to embark on an exciting adventure through the fascinating world of biology-based science experiments!

1. Grow a Butterfly

Students can gain knowledge about the various phases of development, from the egg to the larva to the pupa to the adult butterfly, by studying and taking care of a butterfly during its whole life cycle. This offers students a special chance to learn about the insect life cycle and the metamorphosis process.

Learn more: Elemental Science

2. Dissecting a Flower

Dissecting a flower can aid students in honing their analytical and observational skills. This may also aid in their comprehension of how a flower’s various components interact to facilitate reproduction, which is the flower’s main objective.

Learn More: How to Dissect a Flower

3. Extracting a DNA

The extraction of DNA is an excellent experiment for high school students to gain a better understanding of the principles of molecular biology and genetics. This experiment helps students to understand the importance of DNA in research and its applications in various fields, such as medicine, biotechnology, and forensics.

Learn more: Extracting DNA

4. Looking at Fingerprints

Exploring fingerprints can be a fun and intriguing experiment. This experiment encourages students to develop their problem-solving skills and attention to detail, as they must carefully analyze and compare the various fingerprint patterns.

Fingerprint analysis is a fascinating and engaging experiment that can spark an interest in forensic science and provide students with a hands-on learning experience.

Learn more: Directions to Examine a Fingerprint

5. Cultivate Bacteria on Home Made Agar

This experiment provides a hands-on learning experience for students to understand the principles of microbiology and the techniques used in bacterial culture.

This experiment can also help students to understand the importance of bacteria in our daily lives, their role in human health, and their applications in various fields, such as biotechnology and environmental science.

Learn more: Grow bacteria on Homemade Agar Plates

6. Make a Bioluminescent Lamp

This experiment provides an excellent opportunity for high school students to learn about bioluminescence and the principles of genetic engineering.

Creating a bioluminescent lamp is a fun and engaging way to explore the intersection of biology, chemistry, and physics, making it a perfect experiment for students interested in science and technology.

Learn more: Make Glowing Water

7. Make Plants Move with Light

This experiment can help students understand the role of light in plant growth and photosynthesis and the importance of light as an environmental factor for plant survival.

Learn more: Experiments with Phototropism

8. Test the Five-Second Rule

The “5-second rule” experiment is a simple and fun way to investigate the validity of the popular belief that it is safe to eat food that has been dropped on the ground for less than 5 seconds.

The experiment is an engaging and informative way to explore the science behind a common belief and promote critical thinking and scientific inquiry among students.

Learn more: Five Second Rule

9. Examine How Antibiotics Affect Bacteria

This experiment is an excellent opportunity for high school students to develop their laboratory skills, such as aseptic technique and bacterial culture, and understand the principles of antibiotic resistance and its implications for human health.

Examining how antibiotics affect bacteria is a fascinating and educational experiment that promotes scientific inquiry and critical thinking among students.

Learn more: Learn About Bacteria

10. Look for Cell Mitosis in an Onion

This experiment is an excellent opportunity for high school students to develop their microscopy skills and understand the biological basis of growth and development in plants. This experiment is a fun and informative way to explore the world of cells and their role in the growth and development of living organisms.

Learn more: Onion Root Mitosis

11. Test the Effects of Disinfectants

Testing the effects of disinfectants is an important process in determining their efficacy in killing or reducing the number of microorganisms on a surface or object. Disinfectants can be hazardous if not used correctly, and testing their effects can help students understand how to use them safely.

Students can learn about proper handling techniques and how to interpret safety labels and warning signs.

Learn more: Antiseptic and Disinfectants

12. Microwave Seed Gardening

Microwave seed gardening is a quick and efficient method of germinating seeds, microwave seed gardening can be a useful method for starting seeds, but it should be used with care and in conjunction with other germination methods to ensure the best possible results.

Learn more: Microwave plant

13. Water Bottle Bacteria Swab

This experiment can be a fun and informative way to learn about the importance of keeping water bottles clean and free from harmful bacteria. It can also be used to compare the cleanliness of different types of water bottles, such as metal, plastic, or glass.

Learn more: Swabbing Water Bottles

14. Frog Dissection

Frog dissection can be a valuable tool for teaching anatomy and physiology to high school students, as it provides a comprehensive examination of the internal organs and systems of the frog.

Dissection can be a valuable and engaging experiment for high school students interested in biology and life science.

Learn more: Frog Dissection

15. Witness the Carbon Cycle in Action

By witnessing the carbon cycle in action, learners can gain a better understanding of the interconnectedness of different parts of the Earth’s system and the impact that human activities can have on these processes.

Learn more: Carbon Cycle Lab

16. Investigate the Efficacy of Types of Fertilizer

Investigating the efficacy of different types of fertilizer can be an interesting and informative way to learn about plant growth and nutrition. Investigating the efficacy of different types of fertilizer is a practical and engaging way to learn about plant nutrition and the role of fertilizers in agriculture.

Learn more: Best Fertilizer

17. Explore the Impact of Genetic Modification on Seeds

Exploring the impact of genetic modification on seeds is a fascinating and relevant topic that can spark meaningful discussions and encourage learners to think critically about the role of science and technology in society.

Learn more: Genetically Modified (GM) Crops

18. Yeast Experiment

Another easy to perform experiment for high school students is the yeast. This experiment is simple since all that is required is the removal of four different food samples onto separate plates and a thorough examination of the mold that develops on each sample over time.

Learn more: Grow Yeast Experiment

19. Taste Perception

The human tongue has specialized taste receptors that respond to five primary tastes: sweet, salty, sour, bitter, and umami (savory). Taste perception plays an important role in determining food preferences and dietary habits, as well as influencing the overall eating experience.

Learn more: Taste perception

20. Pea Plant Genetics

A classic pea plant genetics experiment involves cross breeding pea plants with different traits, such as flower color, seed shape, or pod shape.

This experiment can be conducted in a controlled environment, such as a greenhouse, by manually transferring pollen from one plant to another.

Learn more: Gregor Mendel Pea Experiment

21. Comparing Animal and Plant Cells

Comparing animal and plant cells is an important exercise in biology education. Both animal and plant cells are eukaryotic cells, meaning they contain a nucleus and other membrane-bound organelles.

This exercise can help students understand the structure and function of cells, as well as appreciate the diversity of life on Earth.

Learn more: Comparing Plant Cell and Animal Cell

22. Testing Bacteria

Bacteria are easily accessible and can be grown in a laboratory or even at home with simple equipment and materials. This makes it a practical and cost-effective experiment for schools with limited resources.

Learn more: How to grow Bacteria and more

23. The Effect of Light on Growth

Light is a fundamental environmental factor that plays a crucial role in the growth and development of plants. By conducting this experiment, students can gain a deeper understanding of how light affects plant growth and why it is important.

Learn more: The effect of light in Plant Growth

24. Planaria Regeneration

Planaria regeneration allows students to design their own experiments, as they can choose which body parts to remove and study the effects of different variables, such as temperature, pH, or chemical treatments on the regeneration process.

Planaria are easy to obtain and maintain in a laboratory or classroom setting. They are also affordable, making it an ideal experiment for schools with limited resources.

Learn more: Planaria Experiment

25. Making a Seed Board

Making a seed board can be a fun and engaging activity for students, as they can see the progress of their plants over time and share their results with others. It can also foster a sense of responsibility and ownership in caring for their plants.

26. Design an Owl Pellet

Dissecting an owl pellet provides a hands-on learning experience for students, allowing them to practice skills in scientific observation, data collection, and analysis. Students can also learn about the anatomy of the prey species found in the owl pellet.

27. Grow an Herbal Cutting

Growing an herb cutting provides a hands-on learning experience for students, allowing them to practice skills in plant care, experimental design, and data collection. Students can learn about the different stages of plant growth and the factors that affect it.

28. Eat a Cell Model

Creating an edible cell model connects to various disciplines, such as biology, anatomy, and nutrition. Students can learn about the different organelles that make up a cell and their functions, as well as the nutritional value of the food materials used in the model

29. Make a Habitat Diorama

Making a habitat diorama provides a hands-on learning experience for students, allowing them to practice skills in research, creative design, and presentation. Students can learn about different ecosystems and the organisms that inhabit them.

30. Create a Fall Leaf (or Signs of Spring) Journal

Creating a fall leaf (or signs of spring) journal provides a hands-on learning experience for students, allowing them to practice skills in observation, data collection, and analysis. Students can learn about the changes that occur in nature during the fall or spring season.

20 Fun and Interesting Biology Experiments for High School

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Unlike science in middle school, high school biology is a hands-on endeavor. Experiments are a standard part of biology courses, whether they are part of a controlled laboratory class, science fair, or individual student projects. Explore a few fascinating high school biology experiments; and discover ideas for simple and easy biology experiments to incorporate into your curriculum.

Examples of Biology Experiments for High School

Whether you are looking for a science fair project or need to create a project for a class assignment, there are numerous biology projects for teens.

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Frog Dissection

Dissecting a frog is a quintessential part of high school biology. If possible, try to get both female and male specimens for your class so students can see the eggs and compare the insides to the male frog.

Flower Dissection

High schoolers can get a bit squirmy about frog dissection. Have a flower dissection instead. The teens can find and label the female and male parts of the flower. It can be fun for high schoolers to check out flower intricacies under a microscope.

Diversity Among Plant Samples

Another simple biology experiment involves going into your natural environment, such as a local park, to observe diversity among plant samples. To make the experiment more detailed, students can rub collected samples on filter paper to observe which plants present which colors . Teens can work to find out why certain plants present certain colors.

Phototropism

It can be enlightening to show kids how phototropism affects plants. They can set up an experiment by using different materials to affect light. They can see how affecting the light affects the growth of the plant.

Water From Common Sources

Water is everywhere. Unfortunately, water contains numerous elements too. A great experiment is collecting water samples from various sources and viewing them under a microscope. Students can then compare their results and attempt to postulate why a given water source would present more organisms than another would.

Yeast Experiment

Another experiment involves taking a piece of bread to monitor the molds that grow over a period of two weeks.

Taste Perception

Everyone has their own taste. Literally! Some people like sour things while others like sweet. Find out if everyone perceives taste the same way and has the same threshold for taste by doing an in-class experiment.

Disinfectant Effectiveness

Ever wonder how effective hand sanitizer is at killing bacteria? Test it! Grow bacteria in a Petri dish along with paper soaked in peroxide, white vinegar, rubbing alcohol, etc. Find out how each one of them works to inhibit bacteria growth.

Pea Plant Genetics

Students can recreate Mendel's genetic pea plant experiments . By growing pea plants and comparing their phenotypes, students can determine each parent plant's genotype.

Examining Fingerprints

Fingerprints are pretty amazing features on the human body. Not only can you use them to open your phone, but each one is unique . Put your fingerprint on paper and examine the different aspects of the lines and arches on your fingers. Compare fingerprints among everyone in class.

Comparing Animal and Plant Cells

To better understand animal and plant cells, students can compare cells from their cheeks to cells from an onion. Just stain the cells with iodine or another dye to better see the cell structures under a microscope.

Creating a DNA model is a great way to help students understand the structure and function of DNA in genetics. Students can use candy, string, and toothpicks to develop a fairly realistic model of the double helix structure.

Water Bottle Germs

Many people refill their water bottles in high school. But do they add germs or bacteria to the bottle? Is refilling a disposable water bottle safe? Have students take swabs of the water bottles they use and look for bacteria around the lid or on the bottle.

Testing Hair

Teens use a lot of hair products. But do they truly work? Have teens in your class take a few samples of their hair. See what happens to the hair when common hair products are added.

Water Cycle

Understanding the water cycle isn't hard. But teens can look at it firsthand by creating a water cycle experiment. Just have them fill a baggie with water and tape it to a window. They will watch evaporation, condensation, and precipitation in action.

Closed Ecosystem Bottle

It can be hard for students to imagine something having its own ecosystem. However, you can use a plastic bottle to create a closed ecosystem.

Field Survey Biology Experiment

This experiment is great because it is cheap, easy, and you can do it in a variety of areas around your school or send students home with it. The goal is to observe the surrounding area over time and monitor the samples that you collect.

Materials You'll Need

For this experiment, you need to grab:

Jar or baggies to collect samples
Stakes and string or cones help mark an area
Paper or journals for taking notes
Slides, slide covers, and a microscope

Observation Instructions

Take note that you will observe your area for several months, so choose an area that is easy to re-mark or where you can leave the markings up, so you return to the same designated area each time.

Have students choose one spot to observe. The spot should be no more than two to three feet square.
Do you see evidence of animals? (Look for prints, scat or guano, fur, owl pellets, etc.)
What plant life do you see? (Look for moss, lichen, weeds, and other plants).
What fungus do you see? (Look for mushrooms and other fungal growth).
What insects do you see? (Encourage students to look specifically for relationships here - such as connecting mosquitos with water or bees with flowers or a hive).

Sampling and Classroom Instructions

Bring the research back into the classroom by following these instructions.

Guide students to make connections and note relationships in their marked area. Have them inventory the area and draw a crude map of where everything is.
If possible, have students use tweezers and gently take samples of soil, fungus, moss, plant life, insects, etc.
pH value of soil or water
Microorganisms in water
Plant cells under a microscope
Comparative structure of flowers you find
Require students to record everything in their own journal or interactive notebook.

Teacher tip: Set up stations in the classroom for viewing, dissecting, drawing, testing pH, etc. This will allow students some choice in how they proceed with examining their specimens.

Testing for Bacteria

Have students see where the most bacteria are lurking. This experiment is great if you want a lab that has guaranteed results. There is always some kind of bacteria lurking somewhere, just waiting to grow in a student's Petri dish.

These are the materials you are going to need to have on hand.

Prepared Petri dishes, three per student
Sterile swabs
Painter's tape
Scotch tape
Permanent Marker
Graph paper

Material notes : You can also purchase sterile Petri dishes and agar separately; however, it is much more likely students will contaminate the plate before they swab.

Preparing Your Petri Dishes

Prepping your Petri dishes is an essential part of the experiment.

Before opening any materials, have students identify three places (but in one physical location such as at home or at school) that they are going to swab for bacteria. Encourage them to hypothesize about which place they think will grow the most bacteria.
Using the Petri dish, trace three circles on the graph paper and cut it out.
In pencil, draw a line to denote the 'top' of the circle. It doesn't matter where you draw the line, but you will need something to show you how your Petri dish is oriented so you can be sure you're tracking the same colony each time you observe.
On the back of the graph paper circle, note the location where you will take the swab, as well as the date you are taking the swabs. Do this for all three Petri dishes you have.

Collecting Samples

Have students bring their unopened sterile swabs and closed Petri dishes to the site. Carefully, they should:

Set the Petri dish down on a flat surface.
Unwrap the swab.
Swipe the swab across the area they suspect has bacteria.
Lift the lid, gently wipe the used swab across the agar, and close the lid, carefully but quickly.

Hint: Sometimes, it's helpful to tape the Petri dish shut so that the Petri dish doesn't accidentally lose its lid.

Evaluating Results

Now that you've swabbed the areas, it's all about the results.

Have students draw Petri-dish-sized circles in their lab books or on separate graph paper. Draw one week's worth of Petri dishes for each dish the student has.
As the colonies start to grow, have students draw the size in their notebooks, making daily observations. If they cannot observe daily, have them observe on the same day(s) over a month.
They should also be recording the color and other notable features of their bacteria colonies in their lab books.
At the end, the students should write a conclusion of their study.

The Effect of Light on Growth

In this lab, students investigate how light affects plant growth. Students may use any plants, but cress will grow more quickly, so your students can get results faster.

Gather up your materials.

Styrofoam cup or bowl
Potting soil

Instructions

With your materials at the ready, it's time to start your experiment.

On Day 1 - plant seeds in the soil in the cups.
Label the cups according to the light you're going to use. You can compare sunlight vs. complete darkness, or you can compare several types of light.
On each day after the initial day, take a picture of each cup and try to measure the growth, if any.
For your lab entries, measure the sprouts, and note color and shape characteristics.

Planaria Regeneration

In this lab, students watch the rate at which planaria regenerates and test whether how you cut the planaria makes a difference as to how they grow back.

To conduct this experiment, you want to grab.

9 planarias
3 small plastic Petri dishes
1 large plastic Petri dish
1 plastic pipet
1 magnifying glass
1 plastic coverslip
Spring water
Paper towels
Ice pack(optional)

Setup Instructions

Getting the setup right is half the battle when it comes to creating fun and interesting biology experiments for high schoolers.

Start by numbering the three small Petri dishes to ensure nothing gets confused later.
Using the pipet, move a planarian into the large Petri dish.
At this point, you may want to try to set the Petri dish on an ice pack for a few minutes. This isn't totally necessary, but it will slow the planarian down to make it easier to cut.
Right behind the head
Right in the middle
Right towards the tail
Use the pipet to gently transfer each segment to a new Petri dish (with spring water).
Repeat the steps with all remaining worm segments.
Every day, observe the planaria. Regeneration will be considered 'complete' when the photoreceptors (the black dots that look like eyes on the planarian's head) appear.

Scientific Method and High School Biology Experiments

Much of high school biology is focused on instilling the elements of science in students. The scientific method is one of these main focuses. The method prompts participants in science to be investigators and to come up with a guess about what will happen in a given experiment, called a hypothesis. The point of the experiment is then to either prove the hypothesis correct through the experiment or prove it incorrect. This prompts teens to get involved in the scientific method while teaching other scientific skills, such as:

The ability to make a rational estimate based on present factors and knowledge
Close detail and monitoring skills
The possibility of being wrong and how to move past that if it turns out to be the case
Quick thinking skills

As much fun as biology experiments can be, there is an educational component spearheading the experiment.

Fun and Interesting High School Biology Experiments

For teens, high school biology can be fun. Finding the right experiment can help biology pop off the page and become more than just another required course of study. Who knows? Perhaps your student will even be prompted to enter a science fair or a career rooted in science?

10 Awesome Biology Experiments Ideas For High School Aspirants

Science is no fun without practical experiments. Unlike middle school, where you limit your study and inquiry of science to the theoretical realm, high school has a different scene. Experiments are a major part of studying science in high school, and biology all the more so. Biology is fascinating. It makes us wonder at the complex system which makes the human body function efficiently; it has all the answers to the questions of death, sickness, and life. But we must admit that only the theoretical explanation of these complex concepts never suffices to give us a satisfactory understanding. That is where practical experiments come to the rescue.

Therefore, this post will cover 10 fascinating biology experiments that high school students can do independently, even at home.

Cool Experiments To Do In Your Bio Lab

While many are intrigued by art competitions , others are moved toward robotic classes. However, in a bunch of students, there are a few who love biology experiments. Hence, here are a few experiments that can be tried out by high schoolers if biology is the subject that piques their interest:

1. Extract DNA

Everyone knows DNA is the agent behind our hereditary traits. Residing in the cell’s nucleus, it guides major aspects of our physiognomy. Usually, the DNA is not visible to the naked eye, you need a powerful microscope to view it, but with this experiment, you can have a fine look at the DNA with this DNA extracting experiment.

Basically, you will be forcefully breaking down some cell walls of the extracted cells by dipping it into your extraction solution. Adding 35ml of dish soap and 5gm of salt in 240 ml of water will give you the extraction solution. Dip and mix some mashed banana slices into the extract, leading the DNA to head out into the solution. Then we will use some alcohol to force the DNA to join up into large chains that we can actually see. You will get a fluffy white substance, the DNA that is visible to the naked eye, made possible by this extraction experiment.

2. Dissect A Flower

Everyone has theoretically seen and known the different parts of a flower. Some exceptional students might even have that picture inscribed in their memory. Very well if you have that, but the hands-on experience of viewing those parts with your own eyes can definitely beat any other theoretical picture-viewing experience.

So, first thing first, go out and choose a bloom. Observe the flower and point out the petals, stamen, and pistil. Use a razor to remove the stamen and observe the Filament and Anther under magnifying glasses. Wipe out some pollen grains and have a detailed look at it under the microscope while you are at them. Next up, remove the pistil and observe your flower’s ovary, stigma, and style with a magnifying glass. This is the simplest yet a fascinating experiment on the list.

3. Raise A Butterfly

Again, we have the theoretical knowledge of the life cycle of a butterfly. Yet it takes us by surprise and wonder when we see the process through our own eyes. So, get ready to be fascinated by a butterfly’s journey from an ugly worm to a colourful butterfly.

The process is easy. You get a caterpillar, observe it daily, and note the changes. The changes will be as precise as your books have always told you. First off, a butterfly lays an egg and a caterpillar hatches from the egg. The caterpillar eats and grows, shedding its skin several times to accommodate its growing belly. Once the caterpillar reaches the right size, it sheds its skin for the last time, revealing the chrysalis, which quickly hardens. Inside the chrysalis, the caterpillar goes through metamorphosis and changes into a butterfly. At the right time, the butterfly breaks out. It hangs onto the chrysalis for a bit, just until its wings dry out and harden. Then, it flies off in search of nectar.

So, in the end, you will be sitting back and enjoying the release of the butterfly you raised with your own very hands.

4. Frog Dissection

Dissecting a frog is one of those lab activities that fascinate and chill you simultaneously. But before you start with the dissection, make sure you take note of all the outer organs like the skin, legs, head, digits, and urinary outlet (cloaca) of the specimen.

You will need a good scalpel, pins, and a dissection tray to cut the frog. After these things are in place, you are all set to perform the three significant incisions on the specimen. Start by cutting from the jaw to down between the legs, then make two horizontal incisions, one above the neck and the other towards the bottom of its legs. At this point, you will start seeing some organs residing in the abdominal cavity. Repeat the same incision on the frog’s abdomen to open the abdominal cavity. Observe the heart, and identify the major organs like the liver, stomach, intestines, and oviducts.

This experiment will definitely leave you amazed at the complex system of nerves, muscles, and bloods that functions interdependently to sustain a living being. However, this experiment should be done in front of teachers and professors in the lab.

5. Diversity Among Plant Samples

Teens can work to find out why certain plants present certain colors. They can also dissect the flowers of the plants and paste the dissected parts of the flowers in their observation notebooks to make a note of the differences between the flowers of the different species of plants.

6. Yeast Experiment

Another simple and easy experiment on the list for high schoolers is the yeaThis experiment is easy because it only involves taking out four different food samples on different plates and a long-time observation of the mold that grows on each sample.

Studying mold is an excellent way to learn more about ecology and biology. This experiment compares how fast mold grows on different types of foods kept in many American homes. Some of the foods are generally kept in refrigerators to extend shelf life, while others are commonly stored at room temperature. This experiment shows that certain foods grow mold faster than others, which is one reason why these foods are often kept in the refrigerator.

Going a step further, the students can also do research inspired by this experiment and find answers to questions such as: what makes a mold grow? And how does one prevent their growth?

7. Look at cell division under the microscope

Cheap digital microscopes with high magnification power that can be directly connected to your laptop or smartphone are easily available in the market nowadays. You can make use of such microscopes to observe every little thing you find at home or outdoors.

A great experiment to do at home with a microscope is to look at how cells divide in different organisms. One of the easiest is baker’s yeast. With a magnification of at least 400x, you can start discerning the shapes of individual yeast cells in water. You will notice that some of them have little buds on them, which is the way they grow and divide.

Taking it one step further, you can also take the tip of the onion’s root and observe them to study the different stages of mitosis as well.

8. Ferment your own food

Bacteria and yeast are practically geniuses in the art of fermentation. Humans have been taking their help for the longest time to make food items such as bread and alcohol. And it is quite easy to ferment your own food at home.

In most cases, you need a starter culture of the bacteria or fungi that make the food you will be fermenting. You can get it from someone already doing fermentation at home or buy it online. Many options range from kombucha, kefir, or mead to yogurt, cheese, kimchi, and sauerkraut. Each fermented food has different requirements, so ensure you have everything you need before starting. After you have everything in place, you are ready to experiment with this fermented food and its varied tastes.

9. Examining Fingerprints

The tips of each finger of your hand have a combination of lines and features in distinctive patterns that we call fingerprints. Fingerprints are one of the fascinating features of the human body. We have been told that each of us is unique in our light, and our fingerprints prove it to be so. You can analyze your own uniqueness by analyzing your very own fingerprints in this project. All you need is paper, magnifying glass, and stamp ink.

First, you need to press a finger against the ink pad and then against a piece of paper. Then, use the magnifying glass to examine the fingerprints and look for arches, whorls, and loops. You can record your finding on your paper. And then take a friend’s fingerprints to analyze the differences.

10. Create A Fall Leaf (Or Signs Of Spring) Journal

Biology is all about studying life and learning more about our natural surroundings. A Fall Leaf journal or a Signs of Spring journal will help your students learn about the trees and bushes that are in your area. This experiment is easy, needs minimal effort, and is fun and exciting as well.

Things To Remember

Science experiments are interesting by nature, but this aspect of their nature shouldn’t keep us from maintaining our share of vigilant caution. Science experiments could sometimes wreak havoc if we do not take enough caution while doing these experiments. Therefore, in order to prevent yourself from ruining your own experiments, you have to follow some safety instructions while doing these experiments.

Wear covered shoes and long pants while performing any experiment, and keep your hair up so it can’t fall into your experiment or a flame. Don’t carelessly sniff or taste any chemicals; don’t just experiment with everything you get your hands on. Make sure you have your full attention in the experiments, and handle everything with care, especially sharp objects like knives or objects that could produce a flame. And at the end of your experiment, you should also know how to dispose of the waste properly.

In the end of it, what matters the most is that we genuinely imbibe the lessons that we learn from our experiments. These biology experiments will get you further into the fascinating world of biology. If you want to further your knowledge, you may also visit science labs, perform science experiments in the lab, attend workshops and seminars, and meet people and learn from their experiences.

Keep learning, keep experimenting, and keep enjoying the process of learning.

Sananda Bhattacharya, Chief Editor of TheHighSchooler, is dedicated to enhancing operations and growth. With degrees in Literature and Asian Studies from Presidency University, Kolkata, she leverages her educational and innovative background to shape TheHighSchooler into a pivotal resource hub. Providing valuable insights, practical activities, and guidance on school life, graduation, scholarships, and more, Sananda’s leadership enriches the journey of high school students.

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20 Hands-on Biology Activities For Kids

Teaching kids about biology can be a great way to teach them about the world around them and understand the science of life. In this post, we’ll share some easy biology experiments and activities you can do with kids, whether you’re a parent or a teacher. From learning how to build DNA to exploring how plants grow, there are so many fun activities kids will love!

What is Biology?

Biology is the study of living things, and it helps us understand how all living creatures work.

It’s like a big puzzle where scientists, or biologists, try to figure out how plants, animals, and even tiny organisms function. They look at things like how our bodies work, how plants grow, how animals behave, and even how different creatures are related to each other.

Biology covers everything from the tiniest cells that make up our bodies to the vast diversity of life in the world, from the smallest bugs to the biggest whales. It’s like exploring a huge, amazing book about life on Earth.

Why is it important for kids to study biology?

Understanding Life : Biology helps kids understand how all living things, including themselves, work. It’s like learning the owner’s manual for living beings.
Respect for Nature : It teaches kids to appreciate and respect nature, from the tiniest insects to the biggest trees. This respect for the environment is crucial for a sustainable future.
Healthy Living : Biology teaches about the human body and how to stay healthy. Kids learn about nutrition, exercise, and how to take care of their bodies.
Curiosity and Discovery : It encourages curiosity and a love for exploring the world around them. Kids get to be little scientists, asking questions and finding answers.
Environmental Awareness : Biology helps kids understand important topics like climate change, pollution, and conservation. This knowledge empowers them to make the world a better place.

Biology Topics

Plants: Kids can learn about different types of plants, their parts (roots, stems, leaves, flowers), and how they grow. They may also explore the importance of plants in providing food and oxygen for living beings.

Animals: Biology involves studying various animals and their characteristics. Kids can learn about the diversity of animals, their habitats, and how they adapt to survive in different environments.

Human Body: Basic concepts of the human body, such as organs, bones, muscles, and the five senses, can be introduced. Kids can learn how their bodies work and how to keep themselves healthy.

Life Cycles: Biology includes understanding life cycles of different organisms, like butterflies, frogs, and plants. Kids can observe and discuss the stages of growth and development.

Habitats and Ecosystems: Children can explore different habitats, such as forests, deserts, oceans, and learn about the plants and animals. They can also understand the interconnections between living things in an ecosystem.

Microscopic World: Kids can be introduced to the fascinating world of microscopic organisms, such as bacteria and protozoa. They may learn about their importance in nature and human health.

Genetics: In simple terms, genetics can be explained as the study of how traits are passed from parents to offspring. Kids can understand basic inheritance patterns and family resemblances.

Food Chains and Webs: Biology involves exploring food chains and food webs, showing how energy flows from one organism to another in an ecosystem.

Adaptations: Kids can learn how different animals have adaptations that help them survive in their environments, such as camouflage or unique body features.

Nature Observations: Encouraging kids to observe and explore the natural world around them is an integral part of biology. Nature walks, and outdoor activities foster a deeper appreciation for living organisms.

Free Biology Experiments Guide

Download and save this handy biology experiments guide and science process pack for your next science lesson!

Fun Biology Questions to Ask

What is photosynthesis, and how do plants use it?
How do animals adapt to their environments?
What’s the purpose of the heart in our bodies?
How do bees help flowers and plants grow?
Why do we have different seasons, and how does that affect nature?
How do animals communicate with each other?
What’s the role of DNA in living organisms?
How do animals like chameleons change their colors?
What are ecosystems, and why are they important?
What are the 5 senses of the body? Think of fun examples for each one!

Quick Toddler or Preschooler Biology

Start with easy ideas like recognizing common animals, plants, or body parts using pictures and simple books.
Plan activities like planting seeds or observing bugs. Kids learn biology through play and exploration.
Explain things in everyday language. For example, say, “Plants use sunlight for their food” instead of using complex words.
Encourage thinking by asking questions like, “Why do leaves change color in the fall?” It helps kids explore and wonder.
Go on nature walks to see plants and animals. Talk about what you see and how they act.
Share nature stories. Kids remember better when learning is part of a story.
Talk about the 5 senses or do an All About Me activity!

Biology Life Cycle Activities

💡New for the Holidays: Reindeer Facts and Life Cycle for Kids

Life Cycle Bug Play Dough Mats
Ladybug Life Cycle
Frog Life Cycle
Butterfly Life Cycle
Penguin Life Cycle
Bean Sprout Life Cycle
Plant Life Cycle
Bee Life Cycle
Earthworm Life Cycle
Pine Tree Life Cycle
Reindeer Life Cycle and Facts

Biology Experiments To Explore

Explore osmosis.

Kids can discover how water moves in and out of plant cells in this Potato Osmosis Lab . You can also demonstrate this with growing gummy bears !

Make A Heart Model

Create an engaging and educational Heart Model STEM Project with your kids using household items like plastic bottles, bendy straws, and clay.

Extract DNA From Strawberries

Learn how to extract DNA from strawberries in this fun and educational science experiment that uncovers the secrets of DNA and genetics.

Build A Candy DNA Model

Explore how to build a Candy DNA model with this fun and educational edible science activity, perfect for teaching kids about the structure of DNA using candy-like licorice and marshmallows. Make sure to also grab this DNA coloring sheet .

Make A Lung Model

Kids can learn how to make a lung model , which involves creating a simple lung model using a plastic bottle, balloons, and a straw to demonstrate how lungs function when we breathe.

X-Ray Project

Explore the principles of X-rays inspired by scientist Marie Curie’s groundbreaking work, and make your own X-rays with this hands-on STEAM project .

Create A Seed Jar

Explore the fascinating world of seed germination, watch roots grow, and identify the parts of a plant with this Seed Germination Experiment .

Build A Mini Greenhouse

Enjoy growing plants with a mini greenhouse made from plastic bottles . Watch the life cycle of a plant unfold with simple materials from your recycling bin.

Explore Leaf Chromatography

Discover the science of leaf chromatography with this STEM activity that teaches kids about the pigments in leaves and how they change colors during the fall season.

Make Spinach Glow

Transform ordinary spinach that you eat into a glowing green mixture under ultraviolet light! Learn about the pigments present in plants, particularly chlorophyll and how certain pigments can absorb light at one wavelength and emit light at another, resulting in the observed glow.

Dissect A Flower

Learn about the parts of a flower and what they do with a fun printable parts of a flower diagram ! Then gather your own flowers, and do a simple flower dissection to identify and name the parts of a flower.

Color Celery

Set up a celery experiment with food coloring that shows how water travels through a plant.

Explore How Plants Breathe

Learn about plant respiration with a few leaves you can grab from your backyard.

Make Red Cabbage Indicator

Find out how cabbage can be used to test liquids of varying acid levels. Depending on the pH of the liquid, the cabbage turns shades of pink, purple, or green!

Cabbage juice science experiment and making pH indicator from red cabbage

Explore Leaf Veins

Learn about the structure of plant leaves and how water travels through leaf veins . This fun and simple biology experiment is a great way to see behind the scenes of how plants work!

Explore the world of germs by learning about hand hygiene and the importance of proper handwashing techniques using bread.

Make Blubber

How do whales, polar bears or even penguins stay warm? Make blubber and test out how it works as an insulator with this blubber experiment .

Bonus: Printable Biology Worksheets

Learn about where different animals live and various biomes with these printable biomes of the world lapbook project.

Nitrogen Cycle

Discover the fascinating world of the nitrogen cycle and the important role micro-organisms have in this process.

Carbon Cycle

Kids can learn all about the Carbon Cycle and witness the exchange of carbon through various processes.

Animal and Plant Cells

Explore the parts of the animal cell or the plant cell with this simple STEAM project. Or grab the complete Animal and Plant Cells Project Pack here.

Learn all about the double helix structure of DNA with this printable DNA coloring worksheet ! Color in the parts that make up DNA, as you explore our amazing genetic code.

Photosynthesis

Green plants make their own food, and food for us through the process of photosynthesis. Use these photosynthesis worksheets to introduce the steps of photosynthesis.

Pollinators

Explore the important role of pollinators in the reproduction of flowering plants with our printable pollinator activity guide.

Food Chains

These printable food chain worksheets are a great way to learn about the flow of energy through simple food chains in ecosystems.

Animal Adaptions

Find instructions and templates to explore animal adaptions in our printable Animal Adaptations Project Pack .

Animal Migration

Dive into the amazing world of animal migration, and the incredible journeys animal embark on all over the world. Printable activities, and facts.

Add these fantastic reptile worksheets to your study of the animal kingdom, and use them to put together a lapbook project about the fascinating world of reptiles.

Vertebrates and Invertebrates

These printable vertebrate and invertebrate worksheets provide a fun way to learn about two different groups of animals.

Why Do Leaves Change Color

Find out what causes leaves to change color in the fall with this fun Why Do Leaves Change Color lapbook project.

How to Set Up a Biology Project

Want to turn one of these fun biology activities into a science fair project? Then, you will want to check out these helpful resources.

Easy Science Fair Projects
Science Project Tips From A Teacher
Science Fair Board Ideas

Printable Science Projects For Kids

If you’re looking to grab all of our printable science projects in one convenient place plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

90+ classic science activities with journal pages, supply lists, set up and process, and science information. NEW! Activity-specific observation pages!
Best science practices posters and our original science method process folders for extra alternatives!
Be a Collector activities pack introduces kids to the world of making collections through the eyes of a scientist. What will they collect first?
Know the Words Science vocabulary pack includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
My science journal writing prompts explore what it means to be a scientist!!
Bonus STEAM Project Pack: Art meets science with doable projects!
Bonus Quick Grab Packs for Biology, Earth Science, Chemistry, and Physics.

Subscribe to receive a free 5-Day STEM Challenge Guide

~ projects to try now ~.

Simulate the Natural World with Virtual Biology Lab

Virtual Biology Lab is a free, online educational resource provided for educational purposes. VBL simulates natural environments with the way life responds to changing conditions. We provide a world to be explored rather than a path to be followed. Background information and technical instruction help students learn by experimentation. Parameters and conditions adjust easily for observable effects and consequences. Because these are stochastic simulations, no two runs are identical. The data generated are biologically realistic and are displayed numerically and graphically. Typically, students will design experiments and conduct them using our models, but collect and analyze their data in other software.

Students utilize the Virtual Biology Lab models

Modern Design

We are currently transitioning our models from HTML-based to HTML5. The new versions of the models include embedded instructions and background information, as well as enhanced graphics. Older model versions, including the original Java Applets, can be found on the site map page . Take a peek at what it looks like in our “See it in Action” video.

Try the HTML-5 versions of our models by clicking on the images below.

Intuitive…

Island Biogeography

Accurate…

PopGen Fish Pond

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6 Easy Biology Science Experiments for Kids

Let’s dive into studying life and living organisms with a new set of biology experiments for kids! These are all easy and simple to do at home or in your classroom, and all of them are liquid or water-based, so you’ll likely have everything you need on hand to bring these science projects to life. We’ll be exploring osmosis, chromatography, homogenization, transpiration, capillary action, and evaporation.

Related: Check out our other science experiments for kids posts on physics and chemistry !

Gummy Bear Osmosis

“Solute” is a general term that refers to a molecule dissolved in a solution. In a salt water solution, for example, the salt molecules are the solutes. The more salt we put in the solution, the more we increase the concentration of solutes.

Water moves from an area with a lower concentration of solutes to an area with a higher solute concentration. This movement of water molecules is called “osmosis.” In order to examine the process of osmosis and observe how it works, we can look at what happens to gummy bears when they are left to soak in different solutions overnight.

Gummy Bear Osmosis Printable Instructions

-------------------- Advertisement --------------------

-------------------------------------------------------, what you’ll need:.

Two container such as bowls, cups, or jars
Measuring cup
Gummy bears
Add ½ cup of water to each of the two empty containers. Add 1 teaspoon of salt to one of the containers and stir well.
Drop a gummy bear into each container and leave it 8 hours or overnight.
Observe what happened to each gummy bear. Compare the gummy bears to each other, and also to a gummy bear that was not left to soak overnight.

What’s happening?

The concentration of solutes inside the gummy bear is higher than the concentration of solutes in plain water. As a result, in our experiment, the water flowed into the gummy bear causing it to swell, and that’s why the gummy bear grew overnight.

The same is true for the gummy bear placed in the salt water solution. However, the difference in solute concentration wasn’t as great, so less water flowed into the gummy bear. In other words, it took less water to balance out the solute concentration inside and outside the gummy bear. Thus, the gummy bear in the salt water solution grew less than the bear in the plain water solution.

You can experiment with different solute concentrations to see how it affects the outcome. What happens when you add twice as much salt to the overnight water bath? Is there any amount of salt that can be added to keep the gummy bear the same size?

Exploring Chromatography

Chromatography is a technique used to separate out the components of a mixture. The technique utilizes two phases – a mobile phase and a stationary phase. There are several types of chromatography, but in this experiment, we will be looking at paper chromatography.

In paper chromatography, the stationary phase is filter paper. The mobile phase is the liquid solvent that moves over the filter paper. For this experiment, we will use marker ink to examine how chromatography works.

Exploring Chromatography Printable Instructions

Three clear containers such as drinking glasses or mason jars
Coffee filters
Rubbing alcohol
Vegetable oil
Water-soluble marker, any color
Sharpie marker, any color
Mark one container with an “A,” a second container with a “W,” and a third container with an “O.” Fill the bottom of the “A” container with rubbing alcohol, the “W” container with water, and the “O” container with vegetable oil. Make sure the liquid in each container comes up no more than ½ an inch from the bottom.
Take three coffee filters out and measure out 1 inch from the bottom. Mark this spot by drawing a line with the pencil. Make one dot on this line using the water-soluble marker. Do the same with the Sharpie marker.
Place one coffee filter in each container so that the bottom of the coffee filter is submerged in the solvent but the solvent DOES NOT touch the dots of marker ink. The solvent will travel up the coffee filter and past the dots. Watch what happens to the dots as the solvent moves over them.

Like dissolves like, so substances will interact with solvents that are similar to it. Water-soluble marker ink is polar, so it will interact with polar mobile phases such as water and alcohol. When a non-polar solvent such as vegetable oil moves over it, it will not interact, and therefore will not move.

Sharpie marker ink is “permanent” in the sense that it can’t be washed off with water. It isn’t water-soluble. When the rubbing alcohol moves over it, however, we see that the Sharpie ink interacts with it. This is because Sharpie ink contains alcohols in it. Following the principle of “like dissolves like,” it interacts with the rubbing alcohol.

Using Tie-Dyed Milk to Observe Homogenization

Molecules in a solution tend to aggregate with other molecules that are similarly charged. Fat molecules, for instance, will cluster together with other fat molecules. Milk is made up of different types of molecules, including fat, water, and protein. In order to keep these molecules from completely separating to form layers, milk undergoes a process called homogenization.

Even after undergoing homogenization, however, fat molecules floating free in solution will come together when milk is left sitting undisturbed. To visualize this process, and what happens when those molecules are dispersed, we can use food coloring and dish soap.

Using Tie-Dyed Milk to Observe Homogenization Printable Instructions

Full fat milk
1 small bowl
Cotton swabs
Pour some milk into a small bowl. You don’t need a lot of milk for this, just enough to fill the bottom of your bowl. Allow the milk to settle so the surface of the milk is still before moving on to Step 2.
Add a drop of food coloring to the surface of the milk.
Dip a cotton swab in dish soap and touch the swab to the surface of the milk, directly adjacent to the drop of food coloring. What happens to the food coloring?

Have you ever tried to mix oil and water? The fat molecules in oil, just like the ones in milk, are “hydrophobic,” meaning they don’t like to be near charged molecules such as water, and will do whatever they can to keep away from them. To achieve this, they clump together. Because the fat molecules are less dense than water, the fat globules float up and form a layer above the water. In our experiment, we added food coloring to this layer of fat globules.

Dish soap is a detergent. Detergent molecules have a hydrophobic end and a hydrophilic end. Because of this, they are able to form a bridge between the fat molecules and the water molecules, causing the fat globules to break up and disperse. What we’re seeing when we add the dish soap is this dispersal of the fat clusters, carrying the food coloring with it and resulting in a beautiful tie-dyed pattern. The result is more dramatic if you add several drops of food coloring and include a variety of colors.

Making water travel through capillary action

Paper towels are designed to pick up spills quickly, absorbing lots of liquid with only a few sheets. But what is it about paper towels that makes them so absorbent? The answer is, in part, capillary action.

In this experiment, we’ll observe how capillary action works to make paper towels efficient. Using nothing but paper towels and the principles governing capillary action, we’ll make water travel from one container and into another.

Making Water Travel through Capillary Action Printable Instructions

3 containers (cups or jars)
Paper towels
Food coloring
Line up the three containers. Fill the two containers on either end about ¾ full of water. Add several drops of food coloring to each of the jars. Whatever color you use is up to you, but the effect works best if the two colors combine to make a third color. (For instance – yellow and blue make green.)
Fold a paper towel in 4 lengthwise. Place one end of the folded paper towel in one of the containers filled with colored water (make sure the end is immersed in the water) and let the other end hang into the empty container. Repeat using a second paper towel and the remaining filled container.
Let the containers sit for four hours. Check them after 1 hour, 2 hours, and 4 hours. What do you see?

Paper towels are highly porous. These pores function like tiny tubes, or capillaries, to draw up water. Two properties allow this to happen. The first is adhesion. Water molecules are attracted to the walls of the capillaries and “stick” to them. This is enhanced in our experiment because paper towels are made of cellulose molecules that are highly attractive to water. The second property is cohesion. The water molecules like to stick to each other. Together, these two properties allow the water to “travel” along the paper towel against gravity, moving out of one container and dropping into the other.

Efficient paper towels are more porous than less efficient brands, giving them a higher degree of absorbency. Taking this into account, how do you think the progress observed at each time point would differ if you used low quality paper towels instead of highly absorbent ones? How would you expect the color in the middle jar to change if you use a less absorbent paper towel to make the blue water travel, and a more absorbent paper towel to make the yellow water travel?

Observing Xylem in Celery

All plants need water to survive. In order to move water up from the soil and into their shoots and leaves, plants have developed a system of water transport. This system is called “xylem.” We can observe the movement of water through xylem transport by placing stalks of celery in colored water. The colored water moves through the stalk and up into the leaves, making the path of the water through this system visible.

Observing Xylem in Celery Printable Instructions

A container such as a jar or vase
Add 1 cup of water to the empty container. Add 2 drops of food coloring to the water (or however many it takes to achieve the color desired) and stir well to mix.
Choose a celery stalk that has leaves attached to the top. Cut about 1 inch off the bottom of the stalk.
Place the stalk upright in the container, making sure the bottom of the stalk is immersed in the water.
Leave the celery out over night. Observe what happens. Take the celery out of the water and cut it open to get a better look at the path the water took.

Plants use a system called xylem to pull water up from the ground and transport it up through the shoot into their leaves. This process is passive, meaning it doesn’t require any energy in order to occur. That’s why the celery was able to pull water up overnight. The celery pulled colored water through its stalk via the xylem transport system. The colored water traveled all the way into the leaves, staining them.

The xylem transport system can be seen more clearly when the celery is cut. The colored water stains the xylem cells, making them visible.

One phenomenon that drives the flow of water through a plant is transpiration. Transpiration is the name given to the process by which water evaporates from the leaves of a plant. What do you think would happen if we repeated the experiment using a celery stalk whose leaves had been cut off? Try it and see!

How to Make it Rain Indoors

One of the properties of water is that it can exist in different phases. It can exist as a liquid, which is the form we’re most familiar with, and it can also exist as a solid (ice), or gas (water vapor). In this experiment, we’ll take water through two of its phases – liquid and gas. We’ll observe how temperature causes water to move from one phase into another. This will allow us to get a better idea of what happens to water in nature, and the role temperature plays in the water cycle.

How to Make it Rain Indoors Printable Instructions

Large container such as a jar
A ceramic plate
Heat approximately eight cups of water to just steaming. This can be done on the stovetop or the microwave, but a stovetop will give you more control over the heating process.
Pour the water into the jar until it is completely full and allow the jar to sit for five minutes. This will heat the jar for the experiment. After five minutes, discard the water.
Add enough heated water to fill the jar up approximately halfway. Cover the jar opening with the plate, making sure no steam can escape. Let the jar sit for 3 minutes. Observe what happens to the water in the jar. Note any changes you see.
After 3 minutes have passed, place enough ice on top of the dinner plate to cover its surface. Watch what happens to the jar.

The water cycle is responsible for producing rain. Liquid water evaporates, sending water vapor into the atmosphere. When the water vapor reaches the cooler air in the upper atmosphere, it condenses back into water droplets, forming clouds. If too much water condenses, or if the temperature becomes colder, the condensed water will fall back down to earth in the form of rain.

In this experiment, we replicated these conditions to produce “rain.” First, we let the heated water form water vapor inside the jar. The water vapor filled the space between the water surface and the plate. We then added ice to our plate, initiating a quick temperature drop. The lower temperature caused the water vapor to condense. This was visible as water droplets that beaded and ran down the sides of the jar. This is how rain happens. We made it rain inside our jar!

You might also like this lesson plan: Learning About Glowing Animals – Bioluminescence or Biofluorescence?

About the author

How Did the First Cells Arise? With a Little Rain, Study Finds.

Researchers stumbled upon an ingredient that can stabilize droplets of genetic material: water.

Blurry dots of different sizes and colors are scattered across a black background. In the lower left corner, a scale bar indicates the length of 40 micrometers.

By Carl Zimmer

Rain may have been an essential ingredient for the origin of life, according to a study published on Wednesday.

Life today exists as cells, which are sacs packed with DNA, RNA, proteins and other molecules. But when life arose roughly four billion years ago, cells were far simpler. Some scientists have investigated how so-called protocells first came about by trying to recreate them in labs.

Many researchers suspect that protocells contained only RNA , a single-stranded version of DNA. Both RNA and DNA store genetic information in their long sequences of molecular “letters.”

But RNA can also bend into intricate shapes, turning itself into a tool for cutting or joining other molecules together. Protocells might have reproduced if their RNA molecules grabbed genetic building blocks to assemble copies of themselves.

One challenge to building protocells is choosing what to wrap them in. Modern cells are wrapped in membranes, barriers that tightly control how molecules move in and out. But this arrangement would have posed a problem for protocells. They would not have been able to take in the molecules they required to grow or to expel waste.

Some scientists have considered whether protocells formed without a membrane. They drew their inspiration from century-old chemical experiments in which researchers blended chemicals into a liquid. In some cases, some of the chemicals condensed into droplets that floated in the mixture. Could protocells have started off as membrane-free floating droplets?

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23 August 2024

What Science and Nature are good for: causing paper cuts

Paper that is 65 micrometres thick poses the greatest danger of causing a paper cut, a model shows. Credit: Getty

A combination of experiments and theoretical work reveals why only certain types of paper can cut into human skin 1 .

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Arnbjerg-Nielsen, S. F., Biviano, M. D. & Jensen, K. H. Phys. Rev. E. 110 , 025003 (2024).

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Honey Bees: Science Activities for Kids

You may have heard on the news that honey bees are disappearing. The Hive Detectives follows the research of four scientists trying to figure out what is going on, as well as discussing a lot of general information about honey bees.

In the 1990’s I co-authored a set of lesson plans about honey bees, called “ Africanized Honey Bees on the Move ” for the University of Arizona. At the time the Africanized honey bees had just moved into Arizona, and many people were concerned about them. The lesson plans have a number of hands-on activities to do with many aspects of honey bee biology. If you go to a grade level, it will list appropriate lessons. Each lesson has links to activity and information sheets. Many of the lessons can be adapted to mixed-age groups.

Here are some honey bee-related activities and links:

1. Gardening for bees

Honey bees require pollen and nectar from flowers in order to survive. One simple activity is to investigate what kinds of bee-friendly plants grow in your area and have your children design and plant a bee garden.

You may wonder if encouraging honey bees to visit flowers in an area with children might be dangerous. It turns out that bees collecting food, called foraging bees, are not likely to sting unless they are stepped on, caught or otherwise threatened. This might not be an appropriate activity, however, for children who are allergic to bees.

(The first two websites were recommended in the book).

Pollinator.org has free planting guides to help you find appropriate plants.

And don’t forget the Great Sunflower Project mentioned in a previous post.

These flowering plants help all kinds of pollinators, not just honey bees.

2. Honey bees and water

Any idea what these bees are doing?

Honey bees need a lot of water, especially in the summer. They use the water to cool inside the hive, to prevent the wax honeycomb from melting. You can see the tongue, called a proboscis, sucking up the water at the edge of this lily pad.

Getting water can be dangerous business for a honey bee. Honey bees often end up falling in, like the ones you see in swimming pools. Can you design a safe place for honey bees to gather water to add to your garden?

3. Honey bee communication and dances.

One of my favorite lessons was always doing the honey bee waggle dances as a way of learning how honey bees communicate .

Dancing under a polarized sky also has a lot of information about honey bee dances.

4. Honey bee senses

Honey bees perceive the world in a way that is very different from humans.

Honey bee senses lesson

What a bee sees

5. Honey bee and other bee nests

Investigate where honey bees live , where beekeepers keep bees and what it is like inside a hive.

The Insect Architects post has a some information about honey bee homes.

You can supply nest sites for other kinds of bees.

I don’t know whether you can read it, but the sign says “Digger Bee Nest Site.” We have left a patch of soil for the tiny digger bees to nest in.

The solitary and social bees lesson has a explanation of the different kinds of bees and how to construct an orchard mason bee nest .

There are a lot of ways to use honey bees as examples for science and nature lessons. Please let me know if you would like more information about any of these activities or if you have found a great website that helps children learn about honey bees.

Books to help you find out more (linked images and titles go to Amazon):

Plus visit our growing list of children’s books about honey bees at Science Books for Kids.

Note: the book that inspired this post was found at our local library.

bees , Biology , Fun Science Activity

books about honey bees for kids honey bee science activities for children

July 23, 2015 at 9:17 am

Hi. Thank you for all the wonderful, smart ideas to help the honey bees. I am currently researching projects to get my young granddaughters to appreciate what is happening to honey bees, and how THEY can help. They are only 3 years old. Thank You

July 23, 2015 at 11:00 am

I can tell you are passionate about honey bees and I’m sure some of that will rub off on your granddaughters. Thank you for stopping by.

August 15, 2017 at 1:43 pm

I love what you focus on in your links/lessons. I could not get the links to open and was led to a “forbidden” message. How can I access the links? Thanks! Nancy

August 17, 2017 at 10:57 am

The honey bee lessons were recently taken off The University of Arizona website. Let me see what I can do to replace them.

August 21, 2017 at 10:43 am

Okay, I did find one copy available on Amazon . I will keep looking.

August 22, 2017 at 4:59 pm

Sorry folks. Looks like I’m going to have to change a few posts because the lessons are no longer available online.

It’s possible I could rewrite the lesson plans and make them available as an e-book. Would anyone be interested in that option?

July 12, 2019 at 3:27 pm

Yes very much interested. This year is the first year that bees are being included in “The North Pole Village.” I have been asked to put something together. An observation hive is always so interesting but since it is in December bees will be in cluster so I would not be able to use that. Something interactive will make it more fun and more memorable for the children. And if they have something to take home with them it reaches parents too.

August 1, 2019 at 11:41 am

Thanks for your interest. I’ve got an idea for a book about native bees for kids, too. So many projects!

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Article Contents

Introduction, observations, pattern formation by collective segregation of cells, conceptual interpretations, quantitative models, conclusions, video references, acknowledgements.

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Collective motion of cells: from experiments to models

Article contents
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Supplementary Data

Előd Méhes, Tamás Vicsek, Collective motion of cells: from experiments to models, Integrative Biology , Volume 6, Issue 9, September 2014, Pages 831–854, https://doi.org/10.1039/c4ib00115j

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Swarming or collective motion of living entities is one of the most common and spectacular manifestations of living systems that have been extensively studied in recent years. A number of general principles have been established. The interactions at the level of cells are quite different from those among individual animals, therefore the study of collective motion of cells is likely to reveal some specific important features which we plan to overview in this paper. In addition to presenting the most appealing results from the quickly growing related literature we also deliver a critical discussion of the emerging picture and summarize our present understanding of collective motion at the cellular level. Collective motion of cells plays an essential role in a number of experimental and real-life situations. In most cases the coordinated motion is a helpful aspect of the given phenomenon and results in making a related process more efficient ( e.g. , embryogenesis or wound healing), while in the case of tumor cell invasion it appears to speed up the progression of the disease. In these mechanisms cells both have to be motile and adhere to one another, the adherence feature being the most specific to this sort of collective behavior. One of the central aims of this review is to present the related experimental observations and treat them in light of a few basic computational models so as to make an interpretation of the phenomena at a quantitative level as well.

Collective motion or swarming of living entities is one of the most common and spectacular manifestations of living systems. The interactions between two cells are quite different from those among individual animals and, correspondingly, some interesting features of swarming specific to the cellular level have been observed. In most cases the coordinated cellular motion is a helpful aspect of the given phenomenon and results in making a related process more efficient ( e.g. embryogenesis or wound healing), while in the case of tumor cell invasion it appears to speed up the progression of the disease. This review is aimed at both presenting the experimental observations and treating them in light of a few basic computational models to provide a quantitative interpretation as well.

In this introductory section and in the section titled “Need for a quantitative description” we provide the basic definitions of the notions used throughout the manuscript. Many of these were originally introduced for the level of organisms. Flocks of birds, herds or fish schools are perhaps the best known examples of large groups exhibiting fascinating patterns of motion by coordinating their motion in various ways (for an extensive review, see ref. 1 ). Interestingly enough, some of the approaches developed for organisms can also be applied to the description of collective motion of cells as well. Although in some cases we make use of the terminology commonly accepted by the community studying the migration of cells, yet due to our focus on the quantitative interpretation of the related processes, we find that providing an introduction to the quantities and the basic models used throughout this review should be useful for the reader.

Defining collective cell motion

Collective motion is a form of collective behavior: individual units (cells) interact in a simple (attraction/repulsion) or complex way (through a combination of simple interactions). The main feature of collective behavior is that the individual cell's action is dominated by the influence of other cells so that it behaves very differently from how it would behave if it was alone. The pattern of behavior is determined by the collective effects due to the other cells of the system.

For purposes of this review we emphasize two major characteristics of collective cell motion (migration). (1) Cells are physically and functionally connected with each other and connection is maintained during collective motion; (2) these multicellular structures exhibit polarity and the supracellular organization of individual cytoskeletal structures generates traction and protrusion forces for migration.

Although it is tempting to see the migration of loosely associated groups, e.g. germ cells, as a collective migration, they are essentially solitary cells following the same ( e.g. chemotactic) cues and tracks while occasionally contacting each other. Therefore we will not consider the migration of these groups as real collective migration because there is an apparent lack of collective effects.

Collective cell motion can occur in the form of 2-dimensional migration on a tissue surface or as 3-dimensional migration of a multicellular group (also termed: cohort) through a tissue scaffold. In the following we will provide a naturally incomplete list of selected examples for the observed subtypes collective migration from among higher eukaryotes in the context where they are experimentally studied: in embryonic development, wound-healing, vascular and tracheal network formation and in vitro conditions. Next we will collect, where available, some computational models trying to reproduce and explain the experimentally observed phenomena. Again, their list is rather exemplary and incomplete. Additionally, we will guide readers through the field of pattern formation by segregation of collectively moving cells where numerous computational models have been developed and tested.

Main types of collective cell motion

Collective cell migration in two dimensions is perhaps best exemplified by the sheet migration of fish keratocytes (skin cells) isolated from scales, 2 the density-dependent sheet migration of isolated human endothelial cells (lining the inner surface of blood vessels) in culture during wound-healing 3 and the streaming behavior of endothelial cells in dense, confluent monolayers. 4

There are several experimentally observed forms of 3-dimensional collective migration, mostly in morphogenic events. During the gastrulation process in the zebrafish embryo leading to the formation of the mesendodermal (germ line) layer, cells exhibit concerted 3D laminar migration. 5 The primordium of the lateral line organ migrates as one cohesive group with front and rear polarity in a later stage of zebrafish embryonic development giving rise to the chain of mechanosensory organs. 6 Similarly, polarized multicellular strands move collectively during branching morphogenesis of the mammary gland or the fruit fly's tracheal network. 7 The branching morphogenesis of the vascular network of a wide range of species from birds to mammals is also a known example of collective migration of polarized multicellular strands that are forming a tubular network. 8

A somewhat special form of 3-dimensional collective migration is the migration of the completely isolated group of border cells towards the oocyte through the tissue stroma made up of nurse cells in the developing egg chamber of the fruit fly. 9

During collective invasion observed in several human cancer types, such as epithelial cancers and melanomas, detached cell groups with front/rear polarity can migrate across tissues after tissue remodeling by the secretion of metalloprotease enzymes, cleaving the extracellular matrix. In some cancer types, the groups can switch among states ranging from collective migration through partial to complete individual migration in processes termed epithelial-mesenchymal transition (EMT) or mesenchymal-epithelial transition (MET). Their motion is reminiscent of morphogenic events but in a rather dysregulated way with the mechanisms yet to be understood making collective cancer invasion a field of great medical importance but more difficult to study compared to morphogenesis. Excellent reviews have been published on various aspects of collective cancer migration. 10–13

Another interesting domain of life where collective motion is observed and modeled is the world of bacteria. Autonomously moving bacteria rely on motility organelles such as flagella or cilia making their motion very different from the collective motion of adherent tissue cells from higher animals that this Review is focusing on. Although the collective motion of bacteria falls outside the scope of this Review, a very detailed recent review on collective motion emerging at various organizational levels of life offers a good opportunity for comparison. 1

Need for a quantitative description

So far the collective motion of cells was mainly investigated by experimentalists and the corresponding reviews were concentrating on the phenomenological aspects of the related processes. In the second part of this Review we bring into the picture a number of computational models that can be successfully used to quantitatively interpret the observations. The quantitative treatment can be useful from the point of the understanding of the basics, but it has potential relevance for designing further experiments or even treatments in the case of cancer therapies.

Throughout this Review we use the terms collective motion, swarming, flocking or cohort migration as synonyms of coherent or ordered motion of units. In various models, collective motion is an emergent phenomenon arising from disordered, random motion through a transition as a function of relevant parameters of the system. Units of a system where collective motion emerges are (i) rather similar, (ii) moving with similar velocities and capable of changing their direction, (iii) interacting with each other causing effective alignment of motion and (iv) subject to perturbations from their environment.

If motion is disordered, the order parameter will be close to 0, whereas in case of ordered motion it will be close to 1. In experimental work, the actual velocity of individual cells can be measured using various methods ranging from manual tracking to automatic tracking based on e.g. object recognition or particle image velocimetry (PIV).

Collective cell motion in vitro

Sheet migration.

This type of motion is primarily observed in the form of in vitro experiments in which the cells move on a plastic or glass surface, typically coated with a layer of proteins facilitating the motion ( e.g. , extracellular matrix proteins).

As a very characteristic form of 2-dimensional collective motion, the collective migration of keratocytes isolated from goldfish scales was studied by Szabó et al. 2 Based on the experimentally observed phenomenon of density-dependent ordering transition from individual random migration to ordered collective migration they determined this phase transition event as a function of cell density ( Fig. 1 ). This was found to be continuous (second order) transition occurring as cell density exceeded a relatively well-defined critical value (also see Reference video 1).

Sheet migration of epithelial cells in vitro . Phase contrast images showing the collective behavior of primary goldfish keratocytes for three different densities. The normalized density, 〈 ρ 〉, is defined as 〈 ρ 〉 = ρ observed / ρ max , where ρ max is the maximal observed density: 25 cells/100 × 100 micron area. (a) 〈 ρ 〉 = 0.072 (b) 〈 ρ 〉 = 0.212 and (c) 〈 ρ 〉 = 0.588. Scale bar indicates 200 μm. As cell density increases, cell motility undergoes transition to collective ordering. The speed of coherently moving cells is smaller than that of solitary cells. (d–f) depict the corresponding velocities of the cells. From Szabó et al. , (2006) with permission of Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys .

Endothelial and epithelial cells are other cell types that have been used for studying in vitro 2-dimensional collective migration both within an intact cell monolayer and in response to the cell density gradient such as in an experimental scratch-wound model, where cell-free space is created e.g. by removing cells by making a scratch in the monolayer. These studies have considerably advanced our understanding of how such collective migration is organized, e.g. in terms of leadership.

Streaming in cell monolayers

In dense monolayers, endothelial cells and various epithelial cells exhibit an intriguing motion pattern, termed ‘streaming’. Streaming is a globally undirected but locally correlated motion with emergent internal flow patterns appearing and disappearing at random positions without directed expansion of the whole monolayer. Streaming was observed in the endothelial cell layer lining major blood vessel walls in developing bird embryos 14 and also among immune cells in dense lymph nodes. 15 This form of collective motion, which is different from external chemotactic gradient-driven motility or uncorrelated diffusive motion, was analyzed in cultures and modeled by Czirók and coworkers 4 , 16 ( Fig. 2 ).

Streaming motion of endothelial cells in vitro . Cell movement within a bovine aortic endothelial (BAEC) monolayer is visualized by cell trajectories in a phase-contrast image with superimposed cell trajectories depicting movements during 1 h. Red-to-green colors indicate progressively later trajectory segments. Adjacent BAEC streams moving in opposite directions are separated by white lines and vortices are indicated by asterisks. From Szabó et al. (2010) with permission of Phys. Biol .

The role of leadership

The widely accepted approach concerning the nature of migration of groups of cells assumes that “leader cells” situated at the front edge of the group guide the motion of all cells in the group and also provide the necessary traction forces for this. Integration of various intrinsic and extrinsic signals result in the selection of leader cells that polarize and interact with the tissue matrix (see a detailed review: ref. 17 ).

In experiments with mosaic cultures of wild type vs. specific gene-silenced human endothelial (HUVEC) cells Vitorino et al. 3 have found that the sheet migration evoked by scratch-wound and eventually closing of the wound by directed immigration of marginal cells in the cell-free space followed by directed migration of cells localized farther from the boundary is a process regulated in a hypothesized modular way. A functional polarization of cells into leader/pioneer or follower cells occurs at the boundary. Leader cells orient their lamellipodia toward the free space and their motion becomes directed, a process which depends on fibroblast growth factor (FGF) signaling through FGF receptor (FGFR) in the FGFR-RAS-PI3K pathway, but it does not require a concentration gradient of FGF. Migration of the followers several rows behind becomes directed through cell–cell coordination, which depends on the presence of cell surface adhesion molecule VE-cadherin but does not require FGF signaling. Mechanosensing is hypothesized to orient the followers toward the leaders.

The traction forces driving collective migration are generally thought to be exerted by leader cells. However it has been shown 18 that in groups of cultured kidney epithelial (MDCK) cells the traction forces are not exclusively generated by leader cells at the edge but also by cells several rows behind, using cryptic lamellipodia. 19

Motivated by wound-healing experiments Poujade et al. studied the collective motion of MDCK cell layers triggered by experimental opening up of cell-free surface using a microfabrication-based technique (stencil) without cell damage. 20 This setting with undamaged cells suggests no release of chemical signaling factors at the wound site. In the process of invading the new surface, involving the coordination of many cells distant from the border, they also identified leader cells with directionally persistent motion, active protrusions and focal adhesions at the border. These leaders form fingering instabilities that destabilize the border. Leaders and followers are hypothesized to be coupled by mechanical signaling through the observed cadherin cell–cell contacts among leaders and followers as well as by the multicellular actin cytoskeletal belt at the sides of these fingers. Cell–cell adhesion keeps the monolayer cohesive, which produces long-range correlation in the cell velocity field ( Fig. 3 ). Leader cells also originate within the monolayer and are brought to the border by streaming flow.

Formation of multicellular fingers in cell monolayers. Upper panel: micrographs of leader cells 18 h after stencil removal. In each image, a single leader drags a finger. (a) Phase contrast image of a finger preceded by a large leader cell. At the leading edge of this leader there is a very active ruffling lamellipodium (inset: contrast was enhanced on this cell), scale bar: 100 μm. (b) Fluorescence image of the actin cytoskeleton. Particularly visible is the subcortical actin belt along the edges of the finger (arrows), scale bar: 50 μm. Lower panel: snapshot of the velocity field 4 h after removal of the stencil. This image was obtained by particle imaging velocimetry. The two vortices are an illustration of how coordinated the flows can be but are not a general feature. Scale bar: 50 μm. From Poujade et al. (2007) with permission of Proc. Natl. Acad. Sci. U. S. A .

The role of geometrical confinement

The impact of geometrical confinement on 2-dimensional collective cell migration has been brought to focus recently by experiments with micropatterned surfaces permitting cell adhesion. In a confluent population of epithelial cells, collective motion is induced by confinement to areas of physical size below the correlation length of motion measured in the unconfined population. Cell density has a permissive role in this as collective motion does not emerge below confluence. 21 The instructive role of external confinement has been further elucidated by cell velocity field and force distribution mapping experiments. Different in vitro migration modes are induced by 2-dimensional confinement depending on the length scales.

Epithelial cells confined on narrow strips of width comparable to cell size exhibit a contraction–elongation type of motion with increased migration speed. As a contrast, the same cells on a magnitude wider strips move as sheet under tensile state while exhibiting larger coordination and forming vortices of size comparable to tens of cell size. 22 The role of force transmission through intercellular adhesion contacts has a crucial role in collective migration as coherence is fully abolished by even transient disruption of cell–cell adhesions resulting in cells exhibiting random walk. 23

Collective cell motion in vivo

Collective cell motion in avian embryonic vascular network formation.

One of the early stages of avian embryonic development, drawing the attention of many experimentalists due to its accessibility for observations, is an intermediate state between two and three dimensions. It can be viewed as quasi-two-dimensional because three-dimensional motions take place in an environment confined to essentially two dimensions due to the flattened morphology of the embryo.

One of the spectacular processes of early avian development is vasculogenesis: endothelial cell precursors continuously differentiated in a spatially scattered way in the lateral mesoderm or aggregated in the extraembryonic mesoderm self-assemble into tubes, eventually forming the primary vascular plexus, a polygonal tubular network. 14 , 24–26 Initially scattered precursors divide and locally assemble into vessels or migrate to developing vessels and subsequently move towards the embryonic midline and participate in the formation of large vessels and the heart.

Using transgenic quail embryos (Tg(tie1:H2B-eYFP) + ) in which all endothelial precursors specifically express a fluorescent marker (YFP) Sato et al. 14 have provided detailed imaging and analysis of endothelial cells' motion in vivo . On the one hand, these cells move passively with gastrulating tissues towards the midline and, on the other hand, they actively move relative to their environment. By the advanced imaging technique, passive motion can be subtracted from overall motion yielding the active motion of endothelial cells. Their active motion does not seem to follow prepatterns in the environment and it is characterized by switching directionality and an apparent attraction to elongated cells and cell chains (also see Reference videos 2 and 3). Endothelial cells eventually assemble into chains of 3–10 cells, giving rise to polygonal tubes ( Fig. 4 ).

Formation of the primary vascular network in the quail embryo. Upper panel, top: endothelial cell precursors specifically expressing YFP (green) in their nuclei are scattered in the lateral mesoderm at Hamburger-Hamilton stage 8. Upper panel, bottom: the same part of the embryo 4 hours later. Endothelial cells expressing YFP (green) and also labeled with CyC3-conjugated QH1 antibody (red) against a specific endothelial cell surface marker have self-organized into a polygonal tubular network and the presumptive dorsal aorta (vertical tube at right). The scale bar is 100 μm. Exerted from supplementary videos of Sato et al. (2010) with permission of PLoS One , also see Reference videos 2 and 3. Lower panel: cell-autonomous active movement of TIE1 + nuclei, obtained after digitally correcting for the deformations associated with tissue motion in the nascent network during vasculogenesis of the quail. Two consecutive frames, separated by 8 minutes, are shown – the first as red, the second as green. Motile activity is inhomogeneous within the population: some nuclei do not move (appear as yellow, some are marked with circles), while most cells move in a chain-migration fashion (indicated by arrows). At this stage of vasculogenesis, movement directions are highly variable: even in the same vascular segment, groups/chains are seen moving in opposite directions. Scale bar: 200 μm. From Sato et al. (2010) with permission of PLoS One .

Gastrulation of the zebrafish embryo

The universal phenomenon of gastrulation, the formation of the main germ layers of embryos, in various higher animal taxa ranging from fish through amphibians to birds and mammals is an important field where 3-dimensional collective cell migration occurs.

One of the most extensively studied gastrulations is that of the zebrafish, where a crucial phase of the process is the ingression of mesendoderm progenitors from the surface at the mid-phase of epiboly, their ingression followed by coherent migration parallel to the surface toward the forming embryonic body axis ( Fig. 5 ).

Movement of lateral mesendoderm cells in wild-type embryos. (A and B) Bright-field images of an embryo at the beginning of gastrulation (6.5 hours postfertilization [hpf]; (A)) and at midgastrulation (8.5 hpf; (B)) Boxes outline the imaged region in (C). (C) Trajectories of mesendoderm progenitors during midgastrulation stages. Nuclei were tracked and the endpoint of each track is indicated with a sphere. The box depicts the magnified region shown in (D). Embryos were imaged by two-photon excitation microscopy from 6.5 to 8.5 hpf. Animal pole is to the top and dorsal is to the right. From Arboleda-Estudillo et al. (2010) with permission of Curr. Biol .

Performing cell transplantation experiments with various genetically modified embryos and cells Arboleda-Estudillo et al. 5 studied the directionality and movement coordination of mesendoderm progenitors. They have found that directional migration of these cells is not a new collective property but already the property of individual cells moving alone.

Nevertheless the collective migration of mesendoderm cells is impaired and becomes less directed if cell–cell adhesion is defective, as shown by modulating cell–cell adhesion strength through the modulation of E-cadherin expression, the key adhesion molecule in mesendoderm cells (also see Reference videos 4 and 5). To analyze the contribution of cell–cell adhesion to collective mesendoderm migration they used a numerical simulation.

Other aspects of the collective migration of mesendoderm cells in gastrulating zebrafish embryos were studied recently. 27 Single mesendoderm cells or small groups were transplanted ahead of the advancing prechordal plate (the front part of the ingressing mesendoderm), an area most likely permissive for their directional migration. These single motile cells or small groups, however, failed to migrate in the right direction toward the animal pole but stayed in position or migrated backward until joining the advancing prechordal plate where they were quickly re-oriented taking the direction of the prechordal plate through active motion, i.e. they were not dragged or pushed passively. Cell–cell interactions and contact with the endogenous prechordal plate are required to orient the motion of these cells in which the major components are E-cadherin-based adhesion, cell polarity defined by the Wnt-Planar Cell Polarity signaling pathway and directed cell protrusion activity regulated by Rac1 GTP-ase.

Mechanosensing the tension gradient developing within the advancing prechordal plate by an intrinsic mechanism without extrinsic cues is hypothesized to account for this self-organization, a mechanism yet to be explored experimentally.

Various aspects of force generation and regulation in morphogenesis are discussed in an excellent recent review. 28

Collective migration of the posterior lateral line primordium of the zebrafish

The development of the lateral line organ in the zebrafish is a series of 3-dimensional collective migration events that are both well characterized biologically and integrated in a computational model ( Fig. 6 ).

The posterior lateral line primordium couples collective migration to differentiation. Upper panel: an overview of a time-lapse movie showing 10 h of lateral line morphogenesis with Claudin B-GFP. The lateral line primordium migrates at a speed of ∼66 μm h −1 at 25 °C. Forming neuromasts at the trailing edge (dotted lines) decelerate, causing the tissue to stretch, before being deposited. The scale bar is 100 μm. Also see Reference video 6. From Haas and Gilmour (2006) 6 with permission of Dev Cell. Lower panel, (a) Microscopic image of the zebrafish embryo at 42 hpf. The posterior lateral line primordium (pLLP, red box) and rosettes are visible due to Claudin B-GFP marker. Modified from Haas and Gilmour (2006) 6 with permission of Dev. Cell . (b) Schematic image of the pLLP corresponding to the area highlighted in red box in (a). The primordium migrates along the Sdf1 chemokine prepattern (purple stripe), detected by CxCr4 receptor (green). The trailing region of the primordium also express Cxcr7 receptor (overlap of the two receptors is seen in orange).

During organogenesis, the primordium of the lateral line organ, a series of mechanosensory hair cell organs, differentiates from neurogenic placodes on both sides of the embryo's head region. The posterior lateral line primordium (pLLP), which is a cohesive mass of more than 100 cells, then migrates as one cohort along a defined path at the side of the embryo while depositing clusters of neuromast cells transforming into sensory epithelial cells forming a series of connected groups, termed rosettes, constituting the lateral line organ. The migration of the primordium is completed in less than 12 hours (see Reference video 6).

The path followed by the primordium is defined by chemokine, stromal-derived factor 1 (Sdf1a, also termed Cxcl12a), expressed by the surrounding myogenic tissue in a stripe pattern, detected by the primordium through expression of the receptor CxCr4b. Although most cells of the primordium express Cxcr4b, only few cells at the leading tip activate the receptor to direct the polarity of the whole group, hence acting as leader cells. Genetic mosaic experiments have revealed that cells with mutant receptor are specifically excluded from the leading edge implying that adequately functioning CxCr4b receptor is required for becoming a leader cell, whereas it is not required for being a follower cell. Here, mechanical force exerted by leaders on followers through the N-cadherin cell–cell contacts is hypothesized to guide followers.

In the absence of either of the receptors, Cxcr7 or Cxcr4b, or their ligand, Sdf1a, the migration of the primordium is seriously defective. Cxcr7 is thought to be required at the rear to ensure persistent forward migration of the whole primordium while regulating the halting and deposition of rosettes through an intracellular signaling differing from that of Cxcr4b 6 , 29 (a detailed review is also available: ref. 11 ).

As the primordium advances, a fibroblast growth factor, FGF10, expressed in discrete spots by the adjacent tissue induces follower cells to adopt an epithelial cell fate and generate the rosette-like structure. Simultaneously, the trailing region of the primordium slows down and halts causing elongation of the primordium followed by seceding of the rosette. This process correlates with the presence of another receptor of Sdf1a, Cxcr7, expressed only by follower cells mainly at the trailing region of the primordium while there is a large overlap with Cxcr4b expression.

Experimental truncation of the Sdf1a stripe can cause a 180 degree turn of the entire migrating primordium followed by migration in the reverse direction and normal depositing of neuromasts (see Reference video 7). This suggests that there is no polarized distribution or long-range concentration gradient of the chemokine guidance cue, but polarization rather lies in the organization of the migrating primordium itself 6 ( Fig. 7 ).

Overview of a time-lapse movie showing the lateral line primordium undergoing a “U-turn” maneuver. The upper “start” panel shows a rounded primordium; a small group of cells projects backward, causing the tissue to rotate. Once this “U-turn” is complete, the primordium readopts its normal polarized morphology and migrates at normal speed in the reverse direction and even deposits a proneuromast. Also see Reference video 7. From Haas and Gilmour (2006) with permission of Dev. Cell .

By establishing a novel readout of chemokine ligand activity based on visualizing and measuring the turnover of the ligand binding receptor, using a tandem fluorescent protein timer (lifetime tFT) method, Gilmour and coworkers have recently provided direct evidence for the self-generation of the chemokine gradient by the migrating collective itself. 30

The Sdf1a ligand concentration-decreasing activity of the Cxcr7 receptor, expressed at the rear of the primordium, is sufficient to generate a gradient of chemokine activity across the primordium's whole length, dispensing the necessity for pre-existing long-range gradients that may have spatial limitations.

Collective chemotaxis: migration of neural crest cells in embryonic development

During embryonic development of vertebrates, two parallel stripe-shaped areas at the borders of the neural plate on both sides of the forming neural tube detach from the neuroectoderm through an epithelial-to-mesenchyme transition process called delamination and eventually form the neural crest (NC). It is a neurogenic tissue, which becomes segmented, giving rise to various elements of the peripheral nervous system. Additionally, many neural crest cells migrate long distances from their original site at the dorsal midline towards the ventral regions and participate e.g. in the formation of the adrenal gland while others colonize to the forming dermal tissue as pigment cells. This ventral-directed migration of dynamically reshaping cell clusters, streams or cell chains is known to be instructed by several diffusible chemotactic agents (attractants and repellents) produced externally while coherent directional migration is controlled by interactions among cells. Specifically, N-cadherin-mediated contact inhibition of locomotion (CIL), a short range repulsive interaction among neighboring cells facilitates the growth of protrusions at non-inhibited free surfaces leading to directional polarization and higher directional persistence of migration. 31 Cohesion of the group is maintained by longer-range mutual attraction (coattraction) of cells through mutual production and binding of the ligand complement fragment C3a by its receptor C3aR. The directional polarization induced by CIL is stabilized and amplified by the chemokine ligand Sdf1, bound by its receptor Cxcr4, while the migrating collective can functionally differentiate into leaders and followers with dynamic shuffling of roles and the groups themselves can split and reassemble. 32 Compared to single NC cells, a group of various numbers of NC cells can more efficiently migrate towards the chemokine by such ‘collective chemotaxis’. 33 , 34

Collective migration in branching morphogenesis: development of the trachea network

Branching morphogenesis is a form of collective cell migration playing pivotal role in the formation of various structures in embryonic morphogenesis or tissue development or regeneration in adults.

The tracheal system of the fruit fly, D. melanogaster , and the vascular system of birds and mammals are two exemplary areas where branching morphogenesis leading to the formation of a tubular system is studied. A common theme to all these tubular systems is their branched and hierarchical nature. The morphological similarity among various tubular systems is related to similarities between the signaling pathways and biophysical characteristics controlling their branching and growth (for a detailed review, see ref. 35 ).

Experimental work with embryonic model systems led to the identification of ligand–receptor pairs involved in the persistent directional migration and guidance of cell groups forming these structures. They have also improved our understanding how the leader–follower organization of groups is determined by initial symmetry breaking events mediated by other ligand–receptor pairs.

The development of the tracheal system in the fruit fly Drosophila melanogaster takes place without cell proliferation and eventually the collective migration of 10 groups each consisting of ∼80 ectodermal cells is responsible for its formation. Tip cells differentiate as leader cells of the group and produce dynamic cytoskeletal protrusions, and then form the primary branches by migrating toward a fibroblast growth factor (FGF) source produced in defined patches by cells surrounding the group. The tip cell prevents its neighbors from becoming leaders in a process called lateral inhibition. The molecular mechanism of adopting a tip cell fate was studied by Ghabrial and Krasnow 7 and reviewed by Schottenfeld et al. 36 The initial slight differences in FGF receptor signaling are amplified by positive and negative feedback loops and eventually lead to increase in the expression of Notch receptor ligand Delta in the leader tip cell. Delta activates Notch in the neighboring cell which eventually downregulates the FGF receptor pathway and Delta expression in the neighboring cell thus making it less responsive to the FGF signal and becoming a follower stalk cell.

The dynamics of cell fate segregation through lateral inhibition by the Delta/Notch system was studied using mathematical models. 37 , 38 Analysis of a model of a lateral inhibitory system along with a spatial gradient of its input stimulus has revealed that such a system mainly contributes to the robustness of tip-cell selection when the input signal includes random noises, which is frequently the case in complex developmental processes. It has also been shown that lateral inhibitory regulation works more robustly in tip-cell selection than self-inhibition, an alternative means of inhibitory regulation.

Collective migration in branching morphogenesis II: development of the vascular network

A very intensively studied field of branching morphogenesis is vascular sprouting and the formation of vascular networks. Avian embryos have become the model organisms for vascular research due to their ease of accessibility and because of similarities to the vascularization of murine embryos, suggesting a generic mechanism shared by warm-blooded animals. 24 , 39

During embryonic development of warm-blooded animals the first phase of vascular network formation is termed primary vasculogenesis in which endothelial precursors randomly differentiated in the lateral mesoderm self-assembly by active motion into a polygonal network, yet void of fluid. The second phase is termed angiogenesis when this initial vascular network already carries blood and it is further reshaped by vessel sprouting, fusion or withdrawal on demand by surrounding tissues and hemodynamic forces. Angiogenesis, essentially the outgrowth of new vessels from existing vessels, then occurs throughout life as endothelial cells are capable of developing networks in several modes in various biological conditions and tissue environments.

Candidate mechanisms for vascular patterning include: guidance by pre-pattern, contact guidance by extracellular matrix (ECM) and mechanosensing, guidance by interactions modifying the ECM (referred to as ‘ECM memory’) and guidance by chemotactic gradients. A very detailed review of vascular patterning mechanisms has been published recently. 16

In vascular sprouts, the endothelial cells are guided by a single tip cell protruding actin-rich filopodia, followed by a multicellular stalk of endothelial cells, connected by vascular endothelial cadherin (VE-cadherin) at cell–cell junctions successively forming the inner lumen of the new vessel.

As the initial step of vascular sprouting a differentiation step to become leader tip cell vs. follower stalk cell occurs similarly as in tracheal morphogenesis. In endothelial cells the vascular endothelial growth factor (VEGF) and the subsequent Delta–Notch signaling axis determine leader and follower cell fate by lateral inhibition.

Jakobsson et al. studied the molecular mechanism of tip cell selection in angiogenesis in the retina and in embryoid bodies. 8 They have found that endothelial cells dynamically compete for the tip cell position through relative levels of VEGF receptor (VEGFR) subtypes 1 and 2. Dynamic position shuffling of tip cells and stalk cells has been observed in experimental sprouting assays ( Fig. 8 ).

Dynamic observations of tip cell shuffling in sprouting angiogenesis. Time-lapse microscopy images of chimaeric embryoid bodies of wild-type cells expressing DsRed (red) or YFP (green). Red arrow indicates when a green cell is overtaken by a red. From Jakobsson et al. (2010).with permission of Nat. Cell Biol .

Differential VEGFR levels modulate the expression of the Notch ligand Delta (DII4) activating Notch in the neighboring cell, which in turn influences the expression level of VEGFR subtypes. Cells with lower VEGFR1 and higher VEGFR2 levels are more likely to take and maintain the leading position.

Based on data from in vitro and in vivo sprouting experiments with genetic chimaeras Bentley et al. 40 developed a hierarchical agent-based computational model for the simulation of sprouting in uniform and gradient distribution of VEGF. Simulation results show that Notch-dependent regulation of VEGFR2 can function to limit tip cell formation from the stalk in a competitive way ( Fig. 9 ).

(a) The two pathways involved in notch-mediated tip cell fate determination. D1 and D2 are transcriptional delays. R1 and R2 are recovery delays representing the time it takes before gene expression returns to normal. d and s represent expression levels in response to receptor activation or loosely, transcription factors. (b) The pathway as a negative feedback loop, active VEGFR-2 (V0) induces Dll4 (D), which increases active Notch1 (N0) leading to VEGFR-2 inhibition. From Bentley et al. (2008) with permission of J. Theor. Biol .

Vasculogenesis by a biophysical mechanism

Vascular sprouting can be viewed as an emergent process governed, at least in part, by biophysical rules influencing the motion of cells involved.

An in vitro model system where primary vasculogenesis can be studied experimentally is the allantois formed by the lateral extraembryonic mesoderm in both birds and mammals. 41 Within the allantois, vasculogenic cell aggregates, termed blood islands, give rise to sprouts eventually forming a vascular network. Endothelial cells are also capable of forming networks in various in vitro systems, such as 3D collagen hydrogels, where environmental or genetic pre-patterns are obviously missing. 42 , 43 After dynamic competition for tip cell position, angiogenetic sprouts are led by very motile tip cells while similarly motile stalk cells are recruited from aggregates and follow the tip cell while occasionally overtaking it.

It is tempting to think that stalk cells are passively dragged by the tip cell but if so the elongation of the sprout would be limited because the cadherin-mediated cell–cell adhesions, shown to be analogous to surface tension of liquid droplets, would not be able to stabilize the structure beyond a critical length. Due to the Plateau–Rayleigh instability a surface-tension stabilized structure, such as a liquid jet, will break up into drops when its length exceeds its circumference. Sprouts grow beyond this length indicating that stalk cells actively move within an expanding sprout following some sort of a guidance mechanism. To search for a potential guidance mechanism to recruit stalk cells in the expanding sprout Szabo et al. studied sprouting in a simplified in vitro system without chemokines. 44 They have demonstrated that various non-endothelial cell types can also exhibit the sprouting behavior on 2-dimensional surfaces, suggesting a generic mechanism.

Vasculogenesis by chemotaxis

Vascular sprouting can also be viewed as a process guided by autocrine chemotactic signaling where the process relies on the secretion of a diffusible chemoattractant morphogen by cells. 45–47

In avian embryonic vasculogenesis, however, the chemoattractant VEGF165, which likely fits in the model, is produced throughout the embryo and overweighs the low autocrine production, if any, by endothelial cells. The same applies to in vitro 3D collagen invasion assays where endothelial cells readily form sprouts and network in the presence of high concentration of exogenous VEGF in the medium.

These contradictions can be overcome if it is assumed that VEGF binds to the extracellular matrix (ECM) while endothelial cells secrete a proteolytic agent releasing the ECM-bound VEGF creating a local gradient of the “bioavailable” VEGF in the microenvironment of endothelial cell aggregates, pointing towards the aggregates. Such a mechanism has not yet been validated experimentally mainly owing to difficulties in visualizing or measuring morphogen gradients.

A recently emerging hypothesis based on the effect of a diffusible inhibitor also attempts to solve the above contradictions. 16 Experiments with diffusible VEGF receptor (VEGFR1) secreted by endothelial cells show that lack of this secreted receptor severely compromises vascular sprouting, whereas exogenous soluble VEGFR1 production by endothelial cells in the vicinity of emerging sprouts can rescue sprout formation and elongation. 48 , 49 Based on these findings it can be hypothesized that diffusible VEGFR1 secreted by endothelial cells binds and sequesters the otherwise abundant VEGF in the vicinity endothelial cells, creating a VEGF gradient pointing away from these cells.

An interesting field where collective cell motion is involved is the spatial pattern formation by different cell types through the process termed segregation (or sorting). Patterns can form as a response of cells to external guidance cues such as morphogens or chemotactic substances or as a process where instead of external cues the local cell–cell interactions and inherently different mechanical or motility characteristics of cell types give rise to various multicellular patterns by physical segregation of the cell types.

These segregation events bear much significance in the embryonic development of higher animals where differentiation, pattern formation and cell motion take place simultaneously. A recent review summarizes several cell segregation phenomena and corresponding computational models. 50

Pattern formation in cell monolayers in vitro

Basic drives and mechanisms of pattern formation events taking place e.g. during embryonic development can be studied in simplified experimental systems where complexity is reduced and the events are more accessible for quantitative analysis.

In 2-dimensional co-cultures of adherent cells on a rigid substrate Mehes et al. studied the dynamics of segregation of two initially mixed cell populations into distinct clusters by cell migration in an environment lacking pre-defined external cues. 51 They have found that segregation into large multicellular clusters is facilitated by collective effects in cell motion such as an increase in the directional persistence of constituent cells. The growth of such multicellular clusters by consecutive fusion of smaller clusters follows algebraic scaling law with characteristic exponents depending on the collective effects ( Fig. 10 , also see Reference video 8).

Dynamics of 2-dimensional segregation of keratocytes in culture. Upper panel: segregation in mixed co-cultures of primary goldfish keratocytes (PFK, red) and EPC fish keratocytes (EPC, green), consisting of >250 000 cells. Top panel shows initial stage after cell attachment, middle panel shows final stage after 17 hours of cell migration. Scale bar is 500 μm. Also see Reference video 8. Bottom panel: average cluster diameter growth curves calculated from experiments with primary goldfish keratocytes (PFK) or human keratocytes (HaCaT). Exponent values obtained from fitting straight line segments to the experimental curves are shown. Cluster growth curve of simulated segregation of cells without collective motion characterized by exponent value α = 0.33 is shown for reference (black solid line). From Mehes et al. (2012) with permission of PLoS One .

The growth exponent values measured in this cell culture system with self-propelled collective motion exceed the exponent values resulting from computer simulations with diffusively moving segregating units detailed in a report by Nakajima and Ishihara. 52

Pattern formation by segregation in vivo : gastrulation and tissue organization

Three-dimensional segregation of cell populations is most prominent during gastrulation, the early phase of embryonic development resulting in the formation of main germ layers that later on give rise to all tissues. Gastrulation is a spectacular event under the microscope involving collective motion of large number of cells, but although gastrulation events have been known since early embryonic studies at the beginning of the 20th century, the basic mechanisms that provide for both its accuracy and robustness are just being uncovered. Segregation of cell populations with different cell fates into distinct domains is governed by their mechanical properties and active motion, and it is an important driving mechanism of gastrulation and tissue organization. Segregation is also important in other embryonic processes ranging from blastocyst formation to somitogenesis in vertebrates.

Cell segregation was first demonstrated by the experiments of Townes and Holtfreter in which presumptive neural and epidermal cells were isolated from amphibian gastrulae;, subsequently they were mixed and they autonomously sorted into separate tissues. 53 In similar early experiments, mixed cells isolated from the adult Hydra were shown to segregate and form separate tissues. 54

Segregation of various cell types in 3-dimensions was studied in several studies 55–59 aiming to explain the observed configurations of segregated domains, typically the envelopment of one cell type by the other, evolving from an initial mixture of cells. These in vitro segregating systems are considered to be analogous to non-mixing liquids and their segregation is shown to be driven by differences in tissue surface tension (TST) of the constituent cell types. 55 Several reports tested the contribution of cell–cell adhesion 57 , 59 and cell cortex tension 58 , 60 to TST.

Three-dimensional segregation experiments

The dynamics of growth of segregated domain size in 3-dimensions was studied by Foty et al. 55 using mixed cultures of embryonic pigmented epithelial and neural retinal cells, which segregated and formed enveloped structures over time in a configuration determined by surface tensions of the cell types. As a comparison, the segregation of gas and liquid phases was studied under microgravity resulting in similar segregated configuration determined by surface tension ( Fig. 11 ).

Gas and liquid phase ordering and segregation of retinal cells. Upper panel: gas and liquid phase ordering in SF6 under reduced gravity, after a thermal quench of 0.7 mK below the critical point (45.564 C). Gas and liquid eventually order with the liquid phase wetting the container wall and surrounding the gas phase, corresponding to wall-liquid interfacial tension < wall-gas interfacial tension. a , b and c correspond to 120 s, 275 s and 3960 s after quench, respectively. Lower panel: sorting out of chicken embryonic pigmented epithelial cells (dark) from chicken embryonic neural retinal cells (light). The average aggregate size is 200 μm. At the end of sorting, neural retinal cells preferentially wet the external tissue culture medium surrounding the aggregates. Medium-neural retina and medium-pigmented epithelium interfacial tensions are 1.6 dyne cm −1 and 12.6 dyne cm −1 , respectively. a, b and c correspond to 17 h, 42 h and 73 h after initiation of sorting, respectively. From Beysens et al. (2000) with permission of Proc. Natl. Acad. Sci. U. S. A .

The authors have found that both the size of segregated cell domains and segregated gas/liquid domains increase linearly with time.

In a study quantifying the adhesive and mechanical properties of zebrafish germ line progenitor cell types Heisenberg and coworkers investigated the role of tensile forces in cell segregation. 57 Using single-cell force spectroscopy they have measured the cell-cortex tension of these cell types (ectoderm, mesoderm and endoderm) while specifically interfering with actomyosin-dependent cell-cortex tension.

Performing segregation experiments using cell types with altered myosin activity they have demonstrated that differential actomyosin-dependent cell-cortex tension is required and sufficient to direct the segregation of cell types and determines the final configuration of the segregated domains.

The dynamics of 3-dimensional segregation of mixed germ line progenitors of the zebrafish was studied by Klopper et al. 61 As segregation proceeds in this system, the domain consisting of mesoderm cells gradually engulfs the ectoderm domain, which eventually takes the inner position ( Fig. 12 ). The authors have monitored the dependence of the local segregation order parameter on system size and found algebraic scaling and different characteristic exponent values for enveloping and engulfed cells.

Imaging data for different time points in a segregation experiment with zebrafish ectoderm and mesoderm cells in culture. (a) Micro-molds are used to isolate small populations of ecto- and mesoderm cell mixtures labeled fluorescently with red and green nuclei, respectively. (b) Initial images show homogeneously mixed cells distributed throughout the mold. (c) Cells aggregate together on a time scale of roughly 100 minutes. (d) Imaging after sorting clearly shows the segregation of the two cell populations. Scale bar = 100 micron. From Klopper et al. (2010) with permission of Eur. Phys. J. E: Soft Matter Biol. Phys .

In a similar in vitro system composed of two mixed epithelial cell types suspended in micro-molds, Vicsek and coworkers have recently studied the dynamics of 3-dimensional segregation 49 (see Reference video 9). In their experiments the forming domains are adjacent and unlike zebrafish germline progenitors there is no engulfment of one domain by the other.

It was also found that the growth of segregated domain size follows algebraic scaling law and it is fast, typically completed within 6 hours ( Fig. 13 ). These observations are in harmony with simulations of Mones et al. 62 but in contrast to earlier simulations of Chaté and coworkers 63 that suggest a much slower process (see Fig. 25 ).

Snapshots from a segregation experiment with two keratocyte types in culture. Left: initial mixture of primary goldfish keratocytes (stained red) and EPC fish keratocytes (stained green) in a micro-mold after onset of segregation. Right: homotypic cell clusters formed through segregation. Also see Reference video 9. From Mehes and Vicsek (2013) with permission of Complex Adap. Syst. Model .

Pattern formation by segregation is a process that is not confined to embryonic development. In a recent publication Inaba et al. 64 studied the formation of skin pigment patterns in the adult zebrafish. They have demonstrated that segregation of the two pigment cell types eventually forming the stripe pattern is governed by their short-range repulsive electric interactions that spatially orient their migration.

Emerging hypotheses

Two opposing hypotheses have been developed for explaining the origin of tissue surface tension, TST, the main drive of collective cell segregation. One is the differential adhesion hypothesis (DAH), developed by M. Steinberg 65–68 postulating that tissue surface tension is proportional to the intensity of adhesive energy between point object cells. This hypothesis was elaborated in extensive modeling approaches by J. Glazier. 69 Experimental studies showed that TST is proportional to cadherin levels. 57

The other hypothesis is the differential interfacial tension hypothesis (DITH), developed by Harris, 70 Brodland 71 , 72 and Graner, 73 postulating that tissue surface tension arises from cortical tension of individual cells generated by actomyosin contractility, while a cell's mechanical energy changes with the cell shape. This model was also supported by experimental data on cell cortex tension and TST. 58

A model integrating cell–cell adhesion and contractility of cell interfaces in the generation of tissue surface tension, the driving force of cell segregation and tissue spreading, was provided by Manning et al. 74 This model specifies an explicit relationship between surface tension and the ratio of adhesion ( γ ) to cortical tension ( β ). Surface tension exhibits a crossover at γ / β ∼ 2 from adhesion-dominated behavior (DAH) in the regime of γ / β < 2 to a dependence on cortical tension and other mechanical effects in the regime of γ / β > 2.

Experimental proof of the relative weights of adhesion and cell cortex tension in controlling cell–cell contact formation in zebrafish germ layer progenitors and determining the experimentally measurable separation force between cell pairs was provided by Maître et al. 75 Cells are described as fluid objects with viscoelastic cortex under tension and adhesive bonds maintaining cell–cell contacts. Contact expansion is controlled by cell cortex tension at the contact, generated by myosin activity, while adhesion by cadherin molecules (membrane-spanning adhesion molecules) mechanically couple the adhering cells, and such coupling is limited by cadherin anchorage to the sub-membrane cortex. Contact formation is the result of active reduction of cell cortex tension at cell–cell interface, which leads to decrease in cell–cell interface tension, while cell cortex tension at the cell–medium interface will not decrease, accounting for maintained TST. Adhesion is shown to have little direct function in contact expansion. Considering the typical cadherin density, the adhesion energy per unit area of the cell surface (∼1 × 10 −7 N m −1 ) is several orders of magnitude lower than typical TST measured in cell aggregates (being on the order of 1 × 10 −3 N m −1 ). 76–94 The main drive of cell contact formation and segregation is actomyosin-dependent cortex tension rather than adhesion energy.

A recent review emphasizes the role of boundary cells in TST as they can actively change their mechanical properties generating different cortical tensions along their internal and external interfaces. Such ‘mechanical polarization’ is suggested to exert the same net mechanical effect on the tissue as if extra adhesion was introduced among all cells and it is hypothesized to dominate TST instead of the mechanical energy of adhesive bonds. 75 Strong apical-basal actin polarization was shown in surface cells in zebrafish embryonic explants. 77 Considering the low adhesion energy of cadherins, the findings that TST is proportional to the number of surface cadherins 56 can also be interpreted in a way that it is actually signaling through more cadherins leading to increased actomyosin contractility and resultant cell cortex tension which generates higher TST.

When attempting to put the relatively new topic of collective cell migration into a wider perspective we shall consider three major aspects of these phenomena. (i) Collective motion can be looked at as one of the simplest manifestations of collective behavior. (ii) Although a general theoretical framework for such emergent processes as the coherent motion of cells is still lacking, a classification of the collective motion patterns can be a helpful tool for interpreting the various related phenomena. (iii) By using a system of equations the description is, on one hand, elevated to a quantitative level and on the other hand since the same equations can be applied to rather different systems, this also indicates the universal emergent features of the collective motion of cells.

Emergence and collective behavior

Collective behavior applies to a great many processes in nature, which makes it an extremely useful concept in many contexts. Examples include collectively migrating bacteria, insects or birds, simultaneous stopping of an activity ( e.g. , landing of a flock of pigeons) or phenomena where groups of organisms or non-living objects synchronize their signals or motion, e.g. think of fireflies flashing in unison or people clapping in phase during rhythmic applause. The main features of collective behavior are that an individual unit's action is dominated by the influence of its neighbors, the unit behaves differently from the way it would behave on its own; and that such systems show interesting ordering phenomena as the units simultaneously change their behavior to a common pattern.

Over the past decades, one of the major successes of statistical physics has been the explanation of how certain patterns can arise through the interaction of a large number of similar units. Interestingly, the units themselves can be very complex entities too, and their internal structure has little influence on the patterns they produce. It is much more the way they interact that determines the large-scale behavior of the system. Extremely complex units ( e.g. cells, cars, and people) can produce relatively simpler patterns of collective behavior because their interactions (or behavior from the point of view of the outside world) can have a form that is much simpler than the structure of a unit itself.

Classes of collective migration of cells

From a general viewpoint, collectively moving entities may exhibit only a few characteristic motion patterns. Some of these are listed with particular examples in the section on the main types of collective cell motion. Modeling and simulational approaches use the notion of self-propelled particles in order to interpret the various collective motion patterns occurring in a wide range of systems containing units that tend to move with an approximately constant velocity and interact through relatively simple forces (repulsion, alignment, etc. ). The studies have shown that there are only a few possible states of such systems. The list includes the following relevant cases: (i) disordered motion (the direction of motion of the units is not correlated), ordered motion (even distant units move in an approximately same direction), (iii) “turbulent motion” (there is local order but it is lost on a scale much larger than the size of the units), (iv) “steams” of units flowing opposite to each other and finally, (v) “jamming” when the restricted volume and mutual “pushing” of the units results in a highly strained, locally fluctuating but globally not moving groups of particles.

Most of the observations presented above can be looked at as either analogous to one of the above general classes or being a combination of two of them.

Interpreting collective motion of cells in terms of models/equations

In the next section of this Review we shall discuss two types of models both involving equations for the positions and the velocities of the cells. First we shall consider the simplest or “minimal” models, which possess simple rules required for the emergence of collective motion. The second type of models takes into account a few further interactions, already somewhat specific to the particular experimental situation. We shall not discuss the third approach, which comprises systems of partial differential equations (continuum approach) because this framework is very theoretical.

However, all three approaches lead to collective motion patterns similar to many of those observed in experiments. We shall show that indeed, equations can be used to interpret phenomena like, for example, the faster segregation of cells as a result of collective effects. Since the above mentioned equations contain only a couple of terms they cannot account for the large number of potential factors that may influence the detailed, actual motion of a cell. This can be done because details “average out” when the behavior of the whole is considered. As a consequence, it is expected that the collective motion of units has characteristic features typical for many different systems. From the point of statistical physics these could be considered as “universality classes” or major types of behavioral patterns. Observing and interpreting these patterns and their relationship to the systems which exhibit them is likely to lead to a unified picture or, in an ideal case, to the discovery of a number of basic relations or “laws” for the collective motion of cells in various biological processes.

Interactions of various moving cells with their heterogeneous environment, such as in wound healing, embryonic morphogenesis, immune reactions and tumor invasion have been investigated using mathematical models (for a review, see ref. 78 ). As an example, a lattice-gas cellular automaton model has been used for modeling in vitro glioma cell invasion and it allows for direct comparison with morphologies and mechanisms of invading collectives. 79 Computational cell biology, an emerging interdisciplinary field, attempts to mediate among several scientific communities investigating various aspects of cell motion (for a review, see ref. 80 ).

Simplest models

In this section we first quickly review the basic computational models for the swarming behavior in general and for the collective motion of cells as well. In the subsequent sections the more detailed models that are used for explaining specific cellular phenomena will be introduced as well.

As an extension of the above model Chaté and coworkers 82 , 83 added adhesive interactions in the form two-body repulsive-attractive forces and endowed the particles with size.

Although the above models are formulated for the two-dimensional case (sheet migration) it is possible to extend them to three-dimensional cases.

Modeling of sheet migration

A two-dimensional model of collective motion was developed for the sheet migration of keratocytes, 2 detailed in the section ‘Collective cell motion in vitro ’.

The typical simulation results obtained by solving eqn (5) and (6) with periodic boundary conditions, and shown in Fig. 14 , are in agreement with observations on sheet migration ( Fig. 1 ), exhibiting a continuous (second order) phase transition from disordered to ordered phase as a function of increasing cell density used as control parameter.

Computer simulations obtained by solving eqn (5) and (6) for different particle densities. In agreement with the observations, the model exhibits a continuous phase transition from disordered to ordered phase. Also see Reference video 1. From Szabó et al. , (2006) with permission of Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys .

Modeling of streaming in cell monolayers

Cell polarity rule, polarity memory rule.

The cell polarity rule [ eqn (9) ] and the memory rule [ eqn (10) ] together constitute a positive feedback loop. The simulations have been performed applying periodic boundary conditions.

Results from simulations fit well with experimentally observed streaming patterns in endothelial monolayers: streaming motion, shear lines and vortices are seen, as shown in Fig. 15 (also see Reference videos 10 and 11).

Simulation results with low cell adhesion and strong self-propulsion. The inset demonstrates cell trajectories, black lines separate cell streams moving in opposite direction, asterisks show vortices. Also see Reference videos 10 and 11. From Szabó et al. (2010) with permission of Phys. Biol .

Modeling of the role of leadership

Based on experimental data from wound-healing assays with MDCK cell layers and measurable parameters of cell motion Lee et al. 84 developed a mathematical model incorporating the bulk features of single migrating cells and cell–cell adhesions.

The principal driving force in their model comes from the polarization of crawling cells: single crawling cells exert a dipole-distributed force distribution on the substrate. At the edge of the wound this force distribution acts like a pressure pulling the cells out into the cell-free region. Within the cell-filled region the force distribution causes instabilities leading to the experimentally observed flow fields including vortices, jets and fingering-like appearance of the moving boundary ( Fig. 16 ).

Complex flows and border progression in simulated two-dimensional wound healing assays. A characteristic time course from a simulation with an initial width of 200 μm showing the local velocity of the cells (black arrows) and the traction force exerted against the substrate (colormap). Inside the cell-filled region, the cells move with complex dynamics, which includes vortices and long-range correlations in the velocity field. The border advance is non-uniform and shows characteristics of a fingering-type instability. From Lee et al. , 2011 with permission of PLoS Comput. Biol .

In this model the cells are equivalent without differentiation into leaders and followers and as a result the boundary fingering is not as pronounced as what is observed experimentally. Cell–cell adhesions cause the monolayer to act like a viscoelastic fluid that is rigid on short timescales and flows on longer timescales.

This model's behavior such as the dynamics of the boundary advance matches well the data from experiments by Poujade et al. ( Fig. 3 ). 20 In various model simulations they have shown that wound healing may not require substantial biochemical signaling but the process may result only from the typical dynamics of motile cells while intercellular signaling only modifies the force production in cells at different distances from the boundary.

Using computer simulations Kabla 85 studied collective migration and its dependence on the number, motile force and cohesion energy of constituent cells. In these simulations, the degree of global coordination is quantified as mean velocity across the whole population normalized by the mean cell speed (〈 v 〉/〈| v |〉) corresponding to an order parameter taking values from 0 (no order) to 1 (full coordination or sheet migration). This order parameter depends on motile force ( μ ), cohesion energy ( J ) and system size. Typical length scales, λ g ( μ , J ) can be identified corresponding to the largest system size where global coordination can arise spontaneously. For small populations of 10–100 uncoordinated cells it is shown that increase of motile force, μ , or decrease of cohesion energy, J , could trigger sheet migration without the need for specific signaling cues ( Fig. 17 ).

Left: an example of a tissue with a few leader cells (with pink/orange tone) whose polarity is constant and directed towards the right. Right: a sketch of the curve λ c ( μ ) and its qualitative relationship with the different regimes of migration. For a given length scale d associated with a constraint (distance between leaders, distance between boundaries), three regimes can be defined as μ increases: epithelium, sheet migration or uncoordinated. From Kabla (2011) with permission of J. R. Soc. Interface .

The impact of leader cells and the integration of external directionality cues are also discussed. It is assumed here that leader cells are not concentrated at boundaries but scattered throughout the cell population. The susceptibility of the cell population to steering by ‘informed’ leader cells whose directional preference is based on e.g. sensing external cues depends on the distance between leader cells, d l (also manifested as leader cell density) and the collective effects in the bulk of the population.

Small relative number of leader cells (∼1%) are sufficient to coordinate the whole cell population if d l < λ l ( μ , J ) ≈ λ c ( μ , J ) where λ c is the correlation length of the average velocity field in the direction of local velocity, measured in the absence of leader cells.

As each leader cell influences the dynamics of the cells present within a domain of diameter λ c around it, global coordination can be achieved if the density of leader cells is larger than 1 for every domain λ c 2 . This way, large-scale coordination does not require explicit communication between leader and non-leader cells or long-range mechanical coupling through the substrate. Different regimes can be defined for a given correlation length scale as motile force is increased: (non-moving) epithelium, sheet migration and uncoordinated migration ( Fig. 17 ).

Modeling of embryonic vascular network formation

Early vascular network formation is a self-organizing process apparently lacking external prepatterns that vascular precursor cells could follow to get organized into a polygonal network, observed during in vivo development. Based on the simple assumption that endothelial cells preferentially attract to elongated cell structures, Czirok and coworkers performed computer simulations with both an agent-based model 86 and a modified Cellular Potts Model 43 and were able to create polygonal cell structures forming with a dynamism resembling the early vascular network of bird embryos ( Fig. 18 , also see Reference video 12). In the agent-based model, the simulated network of cells evolve into a quasistationary state in which the formation of new branches by preferential attraction mechanism is counterbalanced by coarsening of the network through merger of branches driven by surface tension. The characteristic size of the polygonal network depends on cell density.

Computer simulations of early vasculogenesis by an agent-based model and a modified Cellular Potts Model. Upper panel: network formation in the agent-based model. Randomly placed N = 500 particles assemble into linear structures, detectable already within 30 minutes (a). At a sufficiently high particle density, a characteristic pattern size develops in five hours (b) with a combination of sprouting (branch extension) and coarsening (merger of adjacent branches). Connected dots represent Voronoi neighbor particles. Darkening gray levels indicate increasing local anisotropy. The simulation covered an area of L = 0.7 mm. From Szabo et al. (2007) with permission of Phys. Rev. Lett . Lower panel: the Potts model simulation reaches a stationary state where surface tension-driven coarsening is balanced by the formation of new sprouts. Configurations in the model are shown after 100 (a), 1000 (b), and 30 000 (c) Monte Carlo time-steps. As the structure factors averaged over 10 independent runs reveal, the emerged pattern does not change its statistical characteristics after 1000 steps (a). However, the resulting pattern is not frozen: branches still form and break up. Also see Reference video 12. From Szabo et al. (2008) with permission of Biophys. J .

An alternative mathematical model is based on the assumption that endodermal signaling exerting a paracrine effect on endothelial precursors is mediated by binding to the extracellular matrix deposited by the endothelial precursors. 87

Modeling of gastrulation in the zebrafish embryo

Gastrulation of the zebrafish embryo was studied with the help of a numerical simulation by Arboleda-Estudillo et al. 5 In their simulation the migration of cells is mediated by 4 different force types: (1) a short-range repulsive, mid-range attractive spring force ( f s ) representing cell adhesion; (2) a chemotactic force ( f c ) modeling polarized migration; (3) a “Vicsek et al. type” force, f v , modeling collective migration as each cell attempts to align its direction with its neighbors; (4) noise force ( f n ) modeling random migration.

Modeling of collective migration of the posterior lateral line primordium of the zebrafish

Based on experimental data from lateral line development in the zebrafish Streichan et al. 88 have devised a model integrating numerous known factors of the process ( Fig. 19 ). They propose a dynamically established and maintained mechanism in which there is no need for an already established chemokine ligand gradient to direct the migration of a cell collective. In their model the cell collective actively modulates the isotropically expressed chemokine. The ligand is degraded and co-internalized with receptor, which reduces ligand concentration in the vicinity of the tissue. As the tissue moves it shapes the ligand distribution to an asymmetric profile resulting in a new mean gradient in ligand concentration in the direction of migration. Hence collective migration creates a length- and velocity-dependent polar gradient. Cells encode an initial symmetry breaking in their velocity to shape the chemokine ligand, initiate the traveling wave and maintain the preferred direction of motion.

Upper panel: typical ligand concentration in the vicinity of the rod with the ν > 0 solution shown as dashed cyan line and in the free space shown as solid blue. The green lines denote the front and the rear of the rod. A strong gradient at the front of the rod is observed, whereas in the centre of the rod the new steady-state ligand concentration is reached. The dotted grey profile indicates the symmetric ν = 0 solution. Middle panel: kymograph shows the temporal evolution of the fluorescence signal along a section through the maximum intensity projection of the lateral line primordium. Time is along the y -axis and the section's extension is along the x -axis. At 0 μm, a neuromast deposition is shown: the fluorescence signal of deposited cells becomes stationary, i.e. parallel to the time axis, which corresponds to static cell groups. The front of the tissue continues migration as indicated by straight lines that form an obtuse angle with the x -axis. At about 400 and 700 μm further cell depositions are observed. Lower panel: simulation of the elastic rod with deposition. Deposited parts are dotted grey, the rod is shown as solid green lines and the centre of mass of the rod as a dashed black line. The rod moves to the right and grows at a rate η until a critical length is reached, which leads to the deposition of cells. The remainder continues migration. The speed of the centre of mass decreases until a next deposition is observed. From Streichan et al. (2011) with permission of Phys. Biol .

The model makes predictions on the length-dependent dynamics of the lateral line primordium and the spatio-temporal dynamics of receptor–ligand interaction. Authors identify competition between the front and the rear arising from tissue extensions above a critical length and leading to deposition of cells as the collective migrates along.

Modeling of neural crest cell migration and collective chemotaxis

Collective chemotactic migration of groups of neural crest cells has been subjected to various modelling approaches. An agent-based model has been elaborated by Mayor and coworkers on the basis of the cellular and molecular mechanisms reported so far to underlie neural crest cell migration.

Importantly, this model does not assume neural crest cells to functionally differentiate into leaders or followers. The (i) short-range repulsive interactions corresponding to contact inhibition of locomotion and (ii) longer-range mutual attractive interactions among cells and (iii) migration biased towards a chemotactic gradient have been implemented in the model.

Corresponding simulations have shown that these three are sufficient to reproduce the group migration dynamics of NC cells observed experimentally. 32 An alternative agent-based model of the chain migration of neural crest cells is based on the assumption that leaders and followers differentiate from a homogeneous population NC cells. Leaders are directionally biased towards a target and followers move towards the least resistance in the extracellular matrix opened up by leaders while contact guidance by filopodial interactions among cells further helps them follow the leaders. 89

Modeling of vasculogenesis by a biophysical mechanism

The basic process of vascular network formation is the initiation and development of multicellular sprouts maturated into blood vessels later on. Szabo et al. studied sprouting in a simplified in vitro system without chemokines. 43 Motivated by experimental findings they have developed a model based on the assumption of preferential adhesion to elongated cells ( Fig. 20 ). 90 In their modified Cellular Potts Model cells prefer to be adjacent to other stalk cells rather than staying in the aggregate (see Reference video 13). The presence of persistently moving tip cells and the preferential adhesion assumption are together sufficient to generate expanding sprouts in computer simulations with this model (reviewed in ref. 16 , 91 and 92 ).

Computational model of multicellular sprout elongation: leader cell-initiated sprouting behavior in a computational model system with preferential attraction to elongated cells. (A) Typical time-course of sprout growth: the leader is slightly elongated, thus it pulls passive cells from the initial aggregate. The passive cells become elongated as well and attract further cells into the growing sprout. With sufficient supply of cells, the expansion can continue for an extended time period. (B) Cell trajectories along the sprout direction reveal cells entering the sprout as well as changes in cell order due to differential motion in the sprout. (C) Persistence time of polarity defines sprout shape and length, through the polarity persistence parameter T . When the leader cell is more persistent, longer and straighter sprouts form. From Szabo et al. , (2010) with permission of Math. Modell. Nat. Phenom .

Another approach of modeling angiogenic network formation based on purely local mechanisms was elaborated by Deutsch and coworkers. 93

In their lattice-gas cellular automaton model the increased movement coordination and cell–cell adhesion of simulated cells in response to homogeneous growth factor (VEGF) stimulation is sufficient to result in angiogenic sprouts resembling the image data from in vitro experiments with endothelial cells. 94 In particular, this model does not assume changes in contact guidance or extracellular matrix remodeling or spatial gradient of growth factor.

Modeling of vasculogenesis by chemotaxis

Vascular sprouting can be approached as a process in which cells secrete a diffusible chemoattractant morphogen thereby inducing autocrine chemotactic signaling. 44–46 Glazier and coworkers investigated this mechanism using a computer model. 95 , 96

In their Cellular Potts Model they assume finite compressibility of cells and as a result effective pressure is developed within the aggregate formed by cells migrating toward the chemoattractant produced by the cells while the steepest gradient is at the surface. Chemotaxis and pseudopod formation by a cell is assumed to be inhibited by surrounding cells through a mechanism called ‘contact inhibition’. If random motility fluctuations move a cell away from the cluster it will sense a weaker chemoattractant gradient and the pressure of the compressed cells continues to push the same cell outward, while pseudopod formation of the cell is released from contact inhibition.

Simulations with this model yield sprouts and network formation ( Fig. 21 ) and show that the sprouting process is facilitated by cells' finite cell size, the presence of elongated cells and increased chemotactic sensitivity.

Endothelial cell aggregation; simulation initiated with 1000 scattered cells. (A) After 10 Monte Carlo steps (MCS) (∼5 min). (B) After 1000 MCS (∼8 h). (C) After 10 000 MCS (∼80 h). (D) Contact-inhibited chemotaxis drives formation of vascular networks. Scale bar: 50 lattice sites (≈100 μm). Contour levels (green) indicate ten chemoattractant levels relative to the maximum concentration in the simulation. Grey shading indicates absolute concentration on a saturating scale. From Merks et al. (2008) with permission of PLoS Comput. Biol .

The model also assumes that the main source of the chemoattractant ligand is the endothelial cells themselves. This assumption, however, conflicts with experimental data on the production and abundance of VEGF, the candidate chemoattractant morphogen. This contradiction can be overcome by assuming a secondary mechanism creating a gradient from even distribution of VEGF by sequestration.

A recent computational study 97 has demonstrated that if production of soluble VEGFR1 is proportional to endothelial cell density while VEGF production is uniform and high, a gradient of VEGF-induced signaling through VEGFR2 receptor is established along the sprout surface with highest signaling activity at the sprout tip. Experimental data on a secreted diffusible VEGF receptor support the existence of such a mechanism. 47 , 48

The patterning process based on extension of a structure up the gradient of an external diffusible factor has an established theory. If the concentration of the diffusible factor is kept low at the interface of the cell aggregate while it is uniformly high far from it, and if concentration is proportional to the local curvature of the interface, such a setting results in classic Mullins–Sekerka instability, shown to be responsible for the formation of dense branching patterns in various physical systems. The Mullins–Sekerka instability makes the smooth surface unstable: a spontaneous outgrowth with higher curvature will sense a steeper gradient, which accelerates its growth, provided that adaptation of the gradient is slower than such growth ( Fig. 22 ). This way the instability triggers a spontaneous tip-splitting process creating structures with characteristic branching morphology.

Mullins–Sekerka instability develops when the dynamics of a diffusive field is fast and a stronger gradient accelerates the movement of the interface. In such systems the tip of a ‘sprout’ senses larger gradients in the ‘updated’ concentration field, i.e. in the field that is adapted to the altered shape of the interface. Hence the sprout elongates as long as it can effectively reduce the concentration of the chemoattractant at the tip. Concentration is indicated by orange color, and selected concentrations by black contour lines while red arrows with proportionate lengths point up the gradient that a cell senses. From Czirok (2013) with permission of Wiley Interdiscip. Rev.: Syst. Biol. Med .

The branching process is balanced by the fact that very thin sprout with very large curvature at its tip cannot reduce the diffusible factor concentration so efficiently due to its small size and thus the gradient will become shallower, resulting in slower growth. Eventually, optimal branch width can develop with thicker branches splitting and thinner branches slowing down and growing laterally. While experimental verification is yet to be established, the patterning mechanism based on diffusible secreted inhibitor is a promising approach to understand vascular sprouting.

Modeling of cellular segregation

Several computational models exist that attempt to explain and reproduce the experimentally observed segregation processes in various systems. A widely accepted model based on the Potts model and the idea of differential cell adhesion was developed by J Glazier and co-workers, later termed as the Glazier–Graner–Hogeweg model or the Cellular Potts model. 68 Variants of this model have been successfully employed in simulation studies up to the present day.

Impact of motility on segregation

Dynamic segregation in 2-dimensions was studied by Kabla using Cellular Potts model simulations with self-propelled motile and non-motile cells characterized by identical adhesive properties. 84 Segregation efficiency has been found to depend on the motile forces controlling cell speed, and efficiency reaches maximum at motile forces close to the threshold required for streaming transition. It is also shown by these simulations that differences in motility are sufficient to drive the segregation of cell populations even without difference in adhesion and as a result motile cells will surround the islands of non-motile cells ( Fig. 23 ).

Simulated segregation of motile and non-motile cells. A snapshot of the simulated segregating tissue of motile and non-motile cells at t = 10 6 MCS (Monte-Carlo steps). Membrane tension, J , and motile force, μ , of cells are indicated. From Kabla (2012) 25 with permission of J. R. Soc Interface .

Recently, Nakajima and Ishihara used Cellular Potts model simulations to study the dynamics of the segregation of mixtures of non-self-propelled cell types with diffusive motion. 51 They have found that the increase in the size of segregated domains follows the power law and the growth exponent is n = 1/3 for mixtures with 1 : 1 initial ratio of cell types where segregation proceeds via smoothing of the domain boundary. This is in contrast to previous studies with CPM on smaller simulated systems displaying slower logarithmic growth for domain size. 69 , 98 CPM simulations with self-propelled cell types characterized by identical adhesive interactions as for the simulations by Nakajima and Ishihara 51 also yield domain growth exponent n = 1/3 (A. Czirók, personal communication).

Using Brownian dynamics simulations McCandlish et al. studied dense mixtures of self-propelled and passive rod-like particles in 2-dimensions where only excluded volume interactions can occur. 99 Adhesion properties do not play a role here, particles only differ in motility. Spontaneous segregation of the two particle species generates a rich array of dynamical domain structures with properties depending on the particle shape and propulsion velocity or the combination of these two in the form of the particles' Péclet number, a measure similar to the directional persistence of live cells.

Impact of adhesion on segregation

The role of adhesion in cell segregation was studied by Zhang et al. using Cellular Potts model for simulations. 100 In their model they consider variations in the distribution of adhesion molecules per cells. The speed of segregation is found to increase strongly with interfacial tension that depends on the maximum difference in the number of cadherin adhesion molecules per cell and the reaction-kinetic models of cadherin binding ( Fig. 24 ).

Clustering dynamics of cells with different adhesion characteristics. Snapshots taken from a 5000 cell aggregate simulation with five levels of cadherins showing the dynamics of cluster formation. Time points are denominated as Monte-Carlo steps (MCS). From Zhang et al. (2011) with permission of PLoS One .

Qualitative description of the dynamical features and the geometry of cell segregation depending on intercellular adhesion parameters was provided by Voss-Böhme and Deutsch using a stochastic interacting particle model. 101 In this model the hierarchy of segregation is determined by the strengths of adhesive interactions between cells and the boundary.

In a unique paper combining experimental data and modeling Krieg et al. 58 studied the role of cell-cortex tension and adhesion in the segregation of germ line progenitors of the zebrafish. Carrying out simulations using Cellular Potts Model with cell adhesion and cell-cortex tension data derived from experiments they could reproduce the experimentally observed final configurations of segregating germ line progenitor cell types.

Segregation by collective motion and adhesion

Noise is taken into account by u⃑ t n is a unit vector with random, uniformly distributed orientation.

Having the classic experiments with hydra cells in mind, authors defined two kinds of particles, “endodermic” and “ectodermic”, denoted by 1 and 2, respectively. Accordingly, β 11 and β 22 stand for adhesion within the given cell type, whereas β 12 = β 21 account for symmetric inter-cell-type interactions. Differential adhesion is described by different beta values for symmetric interactions between different cell types. The simulations were performed with cells on a square domain with linear size several magnitudes larger than cell size. Fig. 25 shows snapshots from the evolution of the segregation process. Simulation results are in agreement with experiments of Rieu et al. with dissociated ectodermal and endodermal cells of Hydra viridissima . 102

Segregation dynamics of simulated ectoderm and endoderm cells. Upper panel: cell sorting of 800 cells. The endodermal and ectodermal cells are represented by black and gray circles, respectively. (a) The initial cluster with mixed cell types. (b) The cluster after 3000 time steps and (c) is taken at t = 3 × 10 5 . Clusters of endodermal cells form and grow as time passes by. (d) At t = 2 × 10 6 a single endodermal cluster is formed, but isolated cells remain within the ectoderm tissue, in agreement with experiments of Rieu et al. , 1998. 102 Lower panel: cell sorting in two dimensions from a random, roughly circular initial aggregate of N = 6400 cells in a proportion of 1 : 3 endodermic to ectodermic cells. Evolution of the segregation index, γ , for different α values. The dashed line has a slope − λ = −0.18. Inset: same in three dimensions but with α = 0.01 and β 11 = 8.3. The dashed line has a slope −0.16. From Belmonte et al. (2008) 63 with permission of Phys. Rev. Lett .

In this model, segregation is characterized by an index, γ , showing the average ratio of dissimilar cells around a cell, for either cell types. This index is decreasing as segregation proceeds and it is expected to approach zero in large systems.

Authors have found that segregation is characterized by algebraic scaling laws and introducing even a moderate amount of local coherent motion will considerably speed up the segregation process ( Fig. 25 ).

A variant of this computational model has been published by Beatrici and Brunnet investigating the segregation of self-propelled particles in 2 dimensions, driven by differences only in motility but not in adhesion. 103 In this model, the faster cells envelope the slower cells forming islands as segregation proceeds.

Further developing the model collective motion of Vicsek and coworkers 2 Mones et al. have recently carried out simulations of the segregation behavior of ‘self-propelled’ particle types compared with that of ‘noise-driven’ particle types. 62 To represent interactions with neighbors, particle types were assigned characteristically different two-body attraction/repulsion forces based on experimental data with live cells. Noise-driven particle types, endowed with inherent random motion and no ability to have information from neighbors, segregate with similar dynamism as particles in Potts model simulations by Nakajima and Ishihara, 52 , i.e. exponent values ∼1/3 characterize the growth of segregated domains. As a contrast, self-propelled particles with persistent motion and the ability to align their motion to neighbors in response to impact by neighbors segregate much faster, with growth exponents ∼1, and their dynamism resembles earlier observations of two-dimensional and three-dimensional segregation of cells in culture. 51 , 56

Although three-dimensional simulations and models have been deployed in other fields of cell motion, 79 approaching the phenomenon of three-dimensional segregation with such models remains an area yet to be explored by computational modelers.

The way we approach and understand the events of developmental biology such as collective cell motion and pattern formation by multicellular segregation is gradually shifting from a descriptive view towards a causative understanding of the mechanisms. To facilitate this understanding, integrative biological attempts have been successfully employing various approaches ranging from experimental embryology to statistical physics. The introduction of computational models simulating the behavior of complex developmental systems can also effectively facilitate the way we interpret them. Combination of multi-disciplinary approaches with experimental data can help us design more focused experimental tests or predict yet unseen outcomes. This way they can even further extend our understanding of the dynamic organization of multicellular biological systems.

Reference video 1

Time-lapse sequences of phase contrast images showing the motility of fish epidermal keratocyte cells at three different densities. Each video is 4 hours long. Robust collective behavior can be observed as the density of cells reaches a critical value around 5 × 10 −4 cell per square microns. This spectacular ordering phenomenon resembles the well-known flocking of fish or birds.

B. Szabó, G. J. Szöllösi, B. Gönci, Z. Jurányi, D. Selmeczi, T. Vicsek, Phase transition in the collective migration of tissue cells: experiment and model, Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys. , 2006, 74 , 061908. http://angel.elte.hu/∼bszabo/collectivecells/

Reference video 2

Low magnification dynamic imaging of Tg( tie1 :H2B-eYFP ct2 ) quail embryo. Dynamic imaging of Tg( tie1 :H2B-eYFP ct2 ) quail embryo using Leica DMR upright microscope in DIC and epifluorescence modes with a 5× objective for ∼36 hours every 13 minutes. Scale bar = 600 μm.

Y. Sato, G. Poynter, D. Huss, M. B. Filla, A. Czirok, B. J. Rongish, C. D. Little, S. E. Fraser, R. Lansford, Dynamic analysis of vascular morphogenesis using transgenic quail embryos, PLoS One , 2010, 5 , e12674. http://www.plosone.org/article/fetchSingleRepresentation.action?uri=info:doi/10.1371/journal.pone.0012674.s001

Reference video 3

Time-lapse movie showing Tg( tie1 :H2B-eYFP) cell nuclei (green) surrounded by QH1 + plasma membrane (red) in endothelial cells. Tg( tie1 :H2B-eYFP) quail embryos were injected with QH1-A647 at stages 7 and 8 and time-lapse captured every 13 minutes for 8.5 hours until 15 somites (stage 11). The images were acquired on the upright microscope with the dorsal side against the EC Agar culture using the 10× objective and 2 × 2 binning. 2 × 5 × 9 Mosaic. Scale bar = 100 μm.

Y. Sato, G. Poynter, D. Huss, M. B. Filla, A. Czirok, B. J. Rongish, C. D. Little, S. E. Fraser, R Lansford, Dynamic analysis of vascular morphogenesis using transgenic quail embryos, PLoS One , 2010, 5 , e12674. http://www.plosone.org/article/fetchSingleRepresentation.action?uri=info:doi/10.1371/journal.pone.0012674.s002

Reference video 4

DIC movie of paraxial mesendoderm cells in a wild-type zebrafish embryo between 6 and 8 hours postfertilization. Two exemplary cell couplets were tracked using Fiji software. Yellow arrows indicate transient separation of the tracked cell couplet. Dorsal is to the right and animal to the top. Scale bar represents 14 μm.

Y. Arboleda-Estudillo, M. Krieg, J. Stühmer, N. A. Licata, D. J. Muller, C. P. Heisenberg: Movement directionality in collective migration of germ layer progenitors, Curr. Biol. , 2010, 20 , 161–169. http://www.sciencedirect.com/science/MiamiMultiMediaURL/1-s2.0-S096098220902051X/1-s2.0-S096098220902051X-mmc3.mov/272099/FULL/S096098220902051X/10517fa3273d2ccb74fcd03f973bc28f/mmc3.mov

Reference video 5

DIC Movie of Paraxial Mesendoderm Cells in an e-cadherin Morphant Embryo (4 ng MO per embryo) between 6 and 8 hours postfertilization. Two exemplary cell couplets were tracked using Fiji software. Yellow arrows indicate transient separation of the tracked cell couplet. Dorsal is to the right and animal to the top. Scale bar represents 14 μm.

Y. Arboleda-Estudillo, M. Krieg, J. Stühmer, N. A. Licata, D. J. Muller, C. P. Heisenberg, Movement directionality in collective migration of germ layer progenitors, Curr. Biol. , 2010, 20 , 161–169. http://www.sciencedirect.com/science/MiamiMultiMediaURL/1-s2.0-S096098220902051X/1-s2.0-S096098220902051X-mmc4.mov/272099/FULL/S096098220902051X/83eb5d172ca7a5670a948d4b64a57abf/mmc4.mov

Reference video 6

Low-power overview of lateral line morphogenesis. Imaging allows us to follow the planar path from 28 hpf to 38 hpf. Cells at the trailing edge of the migrating posterior lateral line primordium slow down and eventually stop moving by forming a round proneuromast. Deposited proneuromasts stay interconnected by a chain of cells. The developing pronephros is also labelled by the CldnB::GFP line. Images captured every 4 min using a LSM510 Meta 10×/0.3NA objective.

P. Haas, D. Gilmour, Chemokine signaling mediates self-organizing tissue migration in the zebrafish lateral line, Dev. Cell , 2006, 10 , 673–680. http://www.sciencedirect.com/science/MiamiMultiMediaURL/1-s2.0-S1534580706001195/1-s2.0-S1534580706001195-mmc2.mov/272236/FULL/S1534580706001195/03510571f498e5d3d555136e75519d12/mmc2.mov

Reference video 7

Time-lapse movie shows ⟪u-turn⟫ manoeuvre of the posterior lateral line primordium in an fss mutant embryo at 30 hpf. Note that once the back-flip is complete, the tip of the primordium migrates efficiently in the reverse direction and also deposits pro-neuromasts from the trailing edge. Frames were captured every 2 min using a 20×/0.5NA objective. Movie length: 320 min.

P. Haas, D. Gilmour, Chemokine signaling mediates self-organizing tissue migration in the zebrafish lateral line, Dev. Cell , 2006, 10 , 673–680. http://www.sciencedirect.com/science/MiamiMultiMediaURL/1-s2.0-S1534580706001195/1-s2.0-S1534580706001195-mmc7.mov/272236/FULL/S1534580706001195/9d6b4b912e34b2a07cd1de28afe244bd/mmc7.mov

Reference video 8

Spontaneously segregating primary fish keratocytes and EPC keratocytes in mixed co-culture. Merged double fluorescent + phase contrast time-lapse video showing a segregating co-culture of primary goldfish keratocytes (PFK, red) + EPC keratocytes (green). Note the fast growth of homotypic cell clusters.

E. Méhes, E. Mones, V. Németh, T. Vicsek, Collective motion of cells mediates segregation and pattern formation in co-cultures, PLoS One , 2012, 7 , e31711. http://www.plosone.org/article/fetchSingleRepresentation.action?uri=info:doi/10.1371/journal.pone.0031711.s005

Reference video 9

Merged phase-contrast + fluorescent time-lapse movie of 3-dimensional segregation of mixed tissue cells. Segregation in a mixed co-culture of primary goldfish keratocytes (PFK, red) and EPC fish keratocytes (EPC, green) suspended in agarose micromold is imaged by videomicroscopy. Segregated domains quickly form without engulfment. Fluorescent cell labels: red: cell tracker CMPTX, green: cell tracker CMFDA. Videomicroscopy duration: 20 hours, images were acquired every 10 minutes by a Zeiss Axio Observer system.

E. Méhes, T. Vicsek, Segregation mechanisms of tissue cells: from experimental data to models, Complex Adaptive Syst. Model , 2013, 1 , 4. http://www.casmodeling.com/content/supplementary/2194-3206-1-4-s2.mov

Reference video 10

Phase contrast time-lapse movie of bovine aortic endothelial cells in monolayer. Cells form streams: 5–20 cells move together in narrow, chain-like groups. Trajectories of individual cells are shown in changing colors. Duration: 150 minutes.

A. Szabó, R. Unnep, E. Méhes, W. O. Twal, W. S. Argraves, Y. Cao, A. Czirók, Collective cell motion in endothelial monolayers, Phys. Biol. , 2010, 7 , 046007. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3044241/bin/NIHMS265367-supplement-Movie_1.mov

Reference video 11

Movie of the streaming motion of cells simulated using a self-propelled Cellular Potts model. The feedback between cell polarity and cell displacements yield shear lines and vortices, similar to those seen in endothelial cell monolayers.

A. Szabó, R. Unnep, E. Móhes, W. O. Twal, W. S. Argraves, Y. Cao, A. Czirók, Collective cell motion in endothelial monolayers, Phys. Biol. , 2010, 7 , 046007. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3044241/bin/NIHMS265367-supplement-Movie_3.mpeg

Reference video 12

Simulation movie of network formation of endothelial cells generated by Cellular Potts Model simulation. Preferred adhesion to elongated cells stabilizes and promotes the formation of multicellular sprouts.

A. Szabo, E. Mehes, E. Kosa, A. Czirok, Multicellular sprouting in vitro, Biophys. J. , 2008, 95 , 2702–2710. http://www.sciencedirect.com/science/MiamiMultiMediaURL/1-s2.0-S0006349508784157/1-s2.0-S0006349508784157-mmc4.avi/277708/FULL/S0006349508784157/e2f08f3884c8f08c0bce1b5f732d381e/mmc4.avi

Reference video 13

Cellular Potts Model simulation movie of multicellular sprout elongation. A leader cell (yellow) is assumed to move randomly with a persistent polarity while remaining cells (red) are assumed to prefer adhesion to elongated rather than well-spread cells. This preference helps cells leave the initial aggregate and enter the sprout.

A. Szabó, A. Czirók, The Role of Cell-Cell Adhesion in the Formation of Multicellular Sprouts, Math. Modell. Nat. Phenom. , 2010, 5 , 106. http://pearl.elte.hu/andras/sprout_model.avi

We acknowledge support from the EU FP7 ERC COLLMOT GRANT No: 227878. We thank A. Czirok (Eötvös University, Dept. Biological Physics) for useful consultations.

T. Vicsek and A. Zafeiris Phys. Rep. , 2012 , 517 , 71

B. Szabó , G. J. Szöllösi , B. Gönci , Z. Jurányi , D. Selmeczi and T. Vicsek Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys. , 2006 , 74 , 061908

P. Vitorino and T. Meyer Genes Dev. , 2008 , 22 , 3268

A. Szabó , R. Unnep , E. Méhes , W. O. Twal , W. S. Argraves , Y. Cao and A. Czirók Phys. Biol. , 2010 , 7 , 046007

Y. Arboleda-Estudillo , M. Krieg , J. Stühmer , N. A. Licata , D. J. Muller and C. P. Heisenberg Curr. Biol. , 2010 , 20 , 161

P. Haas and D. Gilmour Dev. Cell , 2006 , 10 , 673

A. S. Ghabrial and M. A. Krasnow Nature , 2006 , 441 , 746

L. Jakobsson , C. A. Franco , K. Bentley , R. T. Collins , B. Ponsioen , I. M. Aspalter , I. Rosewell , M. Busse , G. Thurston , A. Medvinsky , S. Schulte-Merker and H. Gerhardt Nat. Cell Biol. , 2010 , 12 , 943

D. J. Montell , W. H. Yoon and M. Starz-Gaiano Nat. Rev. Mol. Cell Biol. , 2012 , 13 , 631

P. Friedl , Y. Hegerfeldt and M. Tusch Int. J. Dev. Biol. , 2004 , 48 , 441

P. Friedl and D. Gilmour Nat. Rev. Mol. Cell Biol. , 2009 , 10 , 445

P. Friedl , J. Locker , E. Sahai and J. E. Segall Nat. Cell Biol. , 2012 , 14 , 777

O. Ilina and P. Friedl J. Cell Sci. , 2009 , 122 , 3203

Y. Sato , G. Poynter , D. Huss , M. B. Filla , A. Czirok , B. J. Rongish , C. D. Little , S. E. Fraser and R. Lansford PLoS One , 2010 , 5 , e12674

J. B. Beltman , A. F. Marée , J. N. Lynch , M. J. Miller and R. J. de Boer J. Exp. Med. , 2007 , 204 , 771

A. Czirok Wiley Interdiscip. Rev.: Syst. Biol. Med. , 2013 , 5 , 587

A. A. Khalil and P. Friedl Integr. Biol. , 2010 , 2 , 568

X. Trepat , M. R. Wasserman , T. E. Angelini , E. Millet , D. A. Weitz , J. P. Butler and J. J. Fredberg Nat. Phys. , 2009 , 5 , 426

D. T. Tambe , C. C. Hardin , T. E. Angelini , K. Rajendran , C. Y. Park , X. Serra-Picamal , E. H. Zhou , M. H. Zaman , J. P. Butler , D. A. Weitz , J. J. Fredberg and X. Trepat Nat. Mater. , 2011 , 10 , 469

M. Poujade , E. Grasland-Mongrain , A. Hertzog , J. Jouanneau , P. Chavrier , B. Ladoux , A. Buguin and P. Silberzan Proc. Natl. Acad. Sci. U. S. A. , 2007 , 104 , 15988

K. Doxzen , S. R. Vedula , M. C. Leong , H. Hirata , N. S. Gov , A. J. Kabla , B. Ladoux and C. T. Lim Integr. Biol. , 2013 , 5 , 1026

S. R. Vedula , M. C. Leong , T. L. Lai , P. Hersen , A. J. Kabla , C. T. Lim and B. Ladoux Proc. Natl. Acad. Sci. U. S. A. , 2012 , 109 , 12974

A. Czirók , K. Varga , E. Méhes and A. Szabó New J. Phys. , 2013 , 15 , 075006

W. Risau and I. Flamme Annu. Rev. Cell Dev. Biol. , 1995 , 11 , 73

C. J. Drake , S. J. Brandt , T. C. Trusk and C. D. Little Dev. Biol. , 1997 , 192 , 17

P. A. Rupp , A. Czirók and C. D. Little Development , 2004 , 131 , 2887

J. G. Dumortier , S. Martin , D. Meyer , F. M. Rosa and N. B. David Proc. Natl. Acad. Sci. U. S. A. , 2012 , 109 , 16945

C. P. Heisenberg and Y. Bellaïche Cell , 2013 , 153 , 948

G. Valentin , P. Haas and D. Gilmour Curr. Biol. , 2007 , 17 , 1026

E. Donà , J. D. Barry , G. Valentin , C. Quirin , A. Khmelinskii , A. Kunze , S. Durdu , L. R. Newton , A. Fernandez-Minan , W. Huber , M. Knop and D. Gilmour Nature , 2013 , 503 , 285

C. Carmona-Fontaine , H. K. Matthews , S. Kuriyama , M. Moreno , G. A. Dunn , M. Parsons , C. D. Stern and R. Mayor Nature , 2008 , 456 , 957

C. Carmona-Fontaine , E. Theveneau , A. Tzekou , M. Tada , M. Woods , K. M. Page , M. Parsons , J. D. Lambris and R. Mayor Dev. Cell , 2011 , 21 , 1026

E. Theveneau , L. Marchant , S. Kuriyama , M. Gull , B. Moepps , M. Parsons and R. Mayor Dev. Cell , 2010 , 19 , 39

E. Theveneau and R. Mayor Wiley Interdiscip. Rev.: Dev. Biol. , 2012 , 1 , 435

C. R. Horowitz , M. Robinson and S. Seifer Circulation , 2009 , 119 , 2633

J. Schottenfeld , Y. Song and A. S. Ghabrial Curr. Opin. Cell Biol. , 2010 , 22 , 633

C. A. Giurumescu , P. W. Sternberg and A. R. Asthagiri Proc. Natl. Acad. Sci. U. S. A. , 2006 , 103 , 1331

Y. Koizumi , Y. Iwasa and T. Hirashima Biophys. J. , 2012 , 103 , 2549

C. J. Drake and P. A. Fleming Blood , 2000 , 95 , 1671

K. Bentley , H. Gerhardt and P. A. Bates J. Theor. Biol. , 2008 , 250 , 25

A. C. LaRue , V. A. Mironov , W. S. Argraves , A. Czirók , P. A. Fleming and C. J. Drake Dev. Dyn. , 2003 , 228 , 21

R. Montesano and L. Orci Cell , 1985 , 42 , 469

G. E. Davis , S. M. Black and K. J. Bayless In Vitro Cell. Dev. Biol.: Anim. , 2000 , 36 , 513

A. Szabo , E. Mehes , E. Kosa and A. Czirok Biophys. J. , 2008 , 95 , 2702

A. Gamba , D. Ambrosi , A. Coniglio , A. de Candia , S. Di Talia , E. Giraudo , G. Serini , L. Preziosi and F. Bussolino Phys. Rev. Lett. , 2003 , 90 , 118101

G. Serini , D. Ambrosi , E. Giraudo , A. Gamba , L. Preziosi and F. Bussolino EMBO J. , 2003 , 22 , 1771

D. Ambrosi , F. Bussolino and L. Preziosi J. Theor. Med. , 2005 , 6 , 1

N. C. Kappas , G. Zeng , J. C. Chappell , J. B. Kearney , S. Hazarika , K. G. Kallianos , C. Patterson , B. H. Annex and V. L. Bautch J. Cell Biol. , 2008 , 181 , 847

J. C. Chappell , S. M. Taylor , N. Ferrara and V. L. Bautch Dev. Cell , 2009 , 17 , 377

E. Méhes and T. Vicsek Complex Adap. Syst. Model , 2013 , 1 , 4

E. Méhes , E. Mones , V. Németh and T. Vicsek PLoS One , 2012 , 7 , e31711

A. Nakajima and S. Ishihara New J. Phys. , 2011 , 13 , 033035

P. L. Townes and J. Holtfreter J. Exp. Zool. , 1955 , 128 , 53

A. Gierer , S. Berking , H. Bode , C. N. David , K. Flick , G. Hansmann , H. Schaller and E. Trenkner Nature (London), New. Biol. , 1972 , 239 , 98

R. Foty , C. M. Pfleger , G. Forgacs and M. S. Steinberg Development , 1996 , 122 , 1611

D. A. Beysens , G. Forgacs and J. A. Glazier Proc. Natl. Acad. Sci. U. S. A. , 2000 , 97 , 9467

R. A. Foty and M. S. Steinberg Dev. Biol. , 2005 , 278 , 255

M. Krieg , Y. Arboleda-Estudillo , P. H. Puech , J. Käfer , F. Graner , D. J. Müller and C. P. Heisenberg Nat. Cell Biol. , 2008 , 10 , 429

E. Schötz , R. D. Burdine , F. Jülicher , M. S. Steinberg , C. P. Heisenberg and R. A. Foty HFSP J. , 2008 , 2 , 42

J. L. Maître and C. P. Heisenberg Curr. Opin. Cell Biol. , 2011 , 23 , 508

A. V. Klopper , G. Krens , S. W. Grill and C. P. Heisenberg Eur. Phys. J. E: Soft Matter Biol. Phys. , 2010 , 33 , 99

E. Mones , A. Czirók and T. Vicsek , 2014 , arXiv:cond-mat.soft/1401.0951

J. M. Belmonte , G. L. Thomas , L. G. Brunnet , R. M. de Almeida and H. Chaté Phys. Rev. Lett. , 2008 , 100 , 248702

M. Inaba , H. Yamanaka and S. Kondo Science , 2012 , 335 , 677

M. S. Steinberg Proc. Natl. Acad. Sci. U. S. A. , 1962 , 48 , 1577

M. S. Steinberg Science , 1962 , 137 , 762

M. S. Steinberg Science , 1963 , 141 , 401

M. S. Steinberg Dev. Biol. , 1996 , 180 , 377

F. Graner and J. A. Glazier Phys. Rev. Lett. , 1992 , 69 , 2013

A. K. Harris J. Theor. Biol. , 1976 , 61 , 267

G. W. Brodland J. Biomech. Eng. , 2002 , 124 , 188

G. W. Brodland Biorheology , 2003 , 40 , 273

F. Graner J. Theor. Biol. , 1993 , 164 , 455

M. L. Manning , R. A. Foty , M. S. Steinberg and E. M. Schoetz Proc. Natl. Acad. Sci. U. S. A. , 2010 , 107 , 12517

J. L. Maître , H. Berthoumieux , S. F. Krens , G. Salbreux , F. Jülicher , E. Paluch and C. P. Heisenberg Science , 2012 , 338 , 253

J. D. Amack and M. L. Manning Science , 2012 , 338 , 212

S. F. Krens , S. Möllmert and C. P. Heisenberg Proc. Natl. Acad. Sci. U. S. A. , 2011 , 108 , E9

H. Hatzikirou and A. Deutsch Curr. Top. Dev. Biol. , 2008 , 81 , 401

M. Tektonidis , H. Hatzikirou , A. Chauvière , M. Simon , K. Schaller and A. Deutsch J. Theor. Biol. , 2011 , 287 , 131

W. Alt , A. Deutsch and L. Preziosi J. Math. Biol. , 2009 , 58 , 1

T. Vicsek , A. Czirók , E. Ben-Jacob , I. I. Cohen and O. Shochet Phys. Rev. Lett. , 1995 , 75 , 1226

G. Grégoire , H. Chaté and Y. Tu Phys. D , 2003 , 181 , 157

G. Grégoire and H. Chaté Phys. Rev. Lett. , 2004 , 92 , 025702

P. Lee and C. W. Wolgemuth PLoS Comput. Biol. , 2011 , 7 , e1002007

A. J. Kabla J. R. Soc. Interface , 2012 , 9 , 3268

A. Szabo , E. Mehes , E. Kosa and A. Czirok Phys. Rev. Lett. , 2007 , 98 , 038102

A. Köhn-Luque , W. de Back , J. Starruss , A. Mattiotti , A. Deutsch , J. M. Pérez-Pomares and M. A. Herrero PLoS One , 2011 , 6 , e24175

S. J. Streichan , G. Valentin , D. Gilmour and L. Hufnagel Phys. Biol. , 2011 , 8 , 045004

M. L. Wynn , P. M. Kulesa and S. S. Schnell J. R. Soc. Interface , 2012 , 9 , 1576

A. Szabó and A. Czirók Math. Modell. Nat. Phenom. , 2010 , 5 , 106

A. Czirok , B. J. Rongish and C. D. Little Genes Cancer , 2011 , 2 , 1072

A. Czirok and C. D. Little Birth Defects Res., Part C , 2012 , 96 , 153

C. Mente , I. Prade , L. Brusch , G. Breier and A. Deutsch Acta Phys. Pol., B , 2012 , 5 , 99

C. Mente , I. Prade , L. Brusch , G. Breier and A. Deutsch J. Math. Biol. , 2011 , 63 , 173

R. M. Merks , S. V. Brodsky , M. S. Goligorksy , S. A. Newman and J. A. Glazier Dev. Biol. , 2006 , 289 , 44

R. M. Merks , E. D. Perryn , A. Shirinifard and J. A. Glazier PLoS Comput. Biol. , 2008 , 4 , e1000163

Y. L. Hashambhoy , J. C. Chappell , S. M. Peirce , V. L. Bautch and F. Mac Gabhann Front. Physiol. , 2011 , 2 , 62

J. C. Mombach , J. A. Glazier , R. C. Raphael and M. Zajac Phys. Rev. Lett. , 1995 , 75 , 2244

S. R. McCandlish , A. Baskaran and M. F. Hagan Soft Matter , 2011 , 8 , 2527

Y. Zhang , G. L. Thomas , M. Swat , A. Shirinifard and J. A. Glazier PLoS One , 2011 , 6 , e24999

A. Voss-Böhme and A. Deutsch J. Theor. Biol. , 2010 , 263 , 419

J. P. Rieu , N. Kataoka and Y. Sawada Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys. , 1998 , 57 , 924

C. P. Beatrici and L. G. Brunnet Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys. , 2011 , 84 , 031927

Elöod Méhes

Elöod Méhes is a Research Fellow at the Department of Biological Physics of Eotvos University, Budapest. As a cell biologist, he has been focusing on various individual and collective cell motion phenomena, multicellular self-organisation and embryonic development. He has also been involved in developing video microscopic and live cell imaging techniques for in vitro studies of cell motion. As an experimentalist taking a multi-disciplinary approach he is closely collaborating with physicists and computational modelers.

Tamás Vicsek

Tamás Vicsek is a Professor of Physics at the Department of Biological Physics of Eotvos University and Head of the Statistical and Biological Physics Research Group of the Hungarian Academy of Sciences. Over the past 35 years he has been involved in doing computational and experimental research on fractals, pattern formation, granular materials, collective motion (bacterial colonies, flocks, and crowds) and the structure and evolution of complex networks. He has had visiting positions at various research institutes and universities, including Emory University, Yale University and the University of Notre Dame. Tamas Vicsek is a fellow of the American Physical Society and a member of the Hungarian Academy of Sciences.

angiogenesis
endothelial cells
cell adhesion
cell motility
computer simulation
morphogenesis
wound healing
gastrulation
vasculature
embryologic development
tumor cell invasion

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Diversification in social insects

Welcome to the miller lab at the university of missouri - st. louis.

The Social Insect Diversity lab investigates how genomics, behavior, and ecology interact to shape biological diversity. Our primary study systems are the primitively eusocial Polistes paper wasps. What drives speciation and diversification in paper wasps? Does social behavior affect diversification rates in social insects? How does social insect biodiversity compare to that of solitary insects? We explore these questions using a wide range of methods including genome assembly, population genetics, museum collections, behavioral experiments, and more. See our current projects for more information on ongoing research.

University of Missouri - St. Louis

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March 9, 2016

Gone is the solitary genius – science today is a group effort

by Rachel Standish, The Conversation

Scientific discovery was once a mostly solitary endeavour and a common view was that genius was responsible for significant advances in knowledge.

The Nobel Prize – the ultimate prize for discovery – reinforces this perception by awarding no more than three people in each category each year for their contributions to science. Yet, increasingly, scientists are working in large collaborative teams to produce research of exceptional quality.

Ecologists were slower than other scientists to recognise the merit of collaboration . There is a longer history of collaboration among physicists and engineers, driven in part by the need to pool funds to buy equipment necessary for their research.

But ecologists don't need expensive equipment to generate valuable data. In fact, many a dataset has been generated using a metal quadrat , a pencil and a notebook!

Simple equipment requirements belie the complexity of research problems modern-day ecologists are attempting to solve. Collaboration among ecologists can help this effort by increasing the availability and access to data.

Seeking general patterns and processes responsible for these patterns has long been the holy grail of ecology. Collaboration makes this quest achievable.

Nutrient Network

The Nutrient Network represents one successful model of collaboration in ecology. Initiated in 2007, the Nutrient Network is a cooperative globally distributed field experiment designed to understand the degree to which ecological trends uncovered at one site were repeated at multiple sites and in other environments.

From the outset, the coordinators recognised the importance of a simple experimental design. It also had to be inexpensive and easy to install for ecologists working in Serengeti savannah, Brazilian cerrado or Australian desert grasslands.

At last count, the network had grown from six sites in North America to 91 sites distributed across 19 countries around the world.

NutNet data are being used to explore important but largely unanswered questions in ecology. One such question seeks to understand whether a general pattern describes the relationship between productivity, as in yield or plant mass, and diversity, or the number of species, at different spatial scales from local to regional, to global.

The first set of data to describe the relationship was published in 1977. These data were collected from just 14 sites in the vicinity of Sheffield in the United Kingdom.

A more recent test of this relationship included data from 48 NutNet sites on five continents. The globally distributed experiment tested the generality of the pattern described in 1977.

Answers to NutNet questions have implications beyond their contribution to ecology. Increasing recognition of the impacts of human activity on Earth's systems makes global datasets like these more valuable than ever before.

If diversity decreases with increased productivity, then conservation of diversity could be compromised in parts of the world experiencing nutrient enrichment.

For example, a regional study first pointed to the transforming effect of atmospheric nitrogen deposition on chalk grasslands in the Netherlands.

NutNet data have contributed to a broader understanding of the potential impacts of nitrogen deposition on herbaceous vegetation at multiple sites across the globe .

All these studies confirm that nitrogen enrichment increases productivity, which leads to a decline in diversity, presumably due to loss of plant species that can't compete with the plants that grow bigger with more nitrogen.

Collaboration fosters a particular skill set not traditionally associated with nerdy scientists. Being social and working well with others towards a common goal is not what motivated me to study ecology.

I dreamt of working outdoors and learning about nature. Yet my interpersonal skills have become as important as my ability to count, to complete boring repetitive tasks, and to persist with the publication of my research despite sometimes harsh critical review.

Fortunately, the rewards of teamwork are rich in both the significance of what can be achieved and comradely support that develops among team members.

Ironically, collaboration can also foster nerdy scientists. Given the division of labour that comes with collaborative networks, some ecologists can sit at a computer analysing data that others have collected without ever setting foot on field sites. Indeed, ecology is increasingly reliant on people who can analyse and interpret complex datasets.

Collaboration offers a powerful approach to answer outstanding questions in ecology. Research papers having 15 or more contributing authors will soon be the norm.

Increased connectivity via the internet means that ecologists working "down under" are not excluded from collaborative networks. Actually, data from Australia are often highly sought after because the unique combination of climate, soils and species can challenge even the most widely accepted ideas.

Unlike the old perception of scientists as solitary creatures, the new norm is one of collaboration, often across continents.

Source: The Conversation

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October 21, 1999

Has anyone ever done scientific experiments on the effects of human isolation over long periods, months or even years? Such information would seem to be important for manned missions to Mars or beyond.

Nick Kanas, a professor of psychiatry at the University of California, San Francisco, replies:

"You raise a very interesting question. I have reviewed more than 60 reports from studies conducted in space-analogue environments, such as in Antarctica, submarines, land-based and submersible simulators, and from studies of hypodynamia, or confined bed-rest. Many of these have lasted months to a year or more (Antarctic missions and Biosphere 2, for example). My colleagues and I have called into question the salience of such analogue studies for manned space missions, however, especially for issues involving the psychosocial functioning of crew members. For instance, there is some evidence that crew anxiety is expressed differently during Antarctic missions than during hyperbaric (high-pressure) chamber studies because of the differing psychological meanings and degree of danger in these two isolated environments.

"The anecdotal literature (drawn from briefings and reports, for instance) suggests that groups of people working under long-term isolated conditions go through phases of tension and cohesion. For example, the Russians have found that depression-like 'asthenic reactions' are most likely to occur during the long, monotonous middle part of their space missions. Crew tension also seems to be related to crew heterogeneity, as reflected by such factors as gender, cultural background, native language and level of career motivation. People in isolated groups sometimes displace their intra-group tension and anger to the monitoring people on the outside. Finally, in terms of leadership, both task and supportive leadership roles are important for mission success, depending upon the work demands and the degree of monotony experienced by the crew members.

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"Despite the presence of such anecdotal reports, I am not aware of any reports involving scientific studies of psychosocial issues during long-duration manned U.S. and Russian space missions. In a new study funded by NASA, my colleagues and I are studying crew-member and mission-control tension, cohesion and leadership issues that arise during five NASA/Mir space missions, each lasting four to six months. We hope to gather data that will be of use in training and supporting future crews involved with the international space station and perhaps with a future mission to Mars."

JoAnna Wood of the Psychology and Behavior Laboratory at the National Aeronautics and Space Administration's Johnson Space Center offers the following information:

"There has been a fair amount of research on this topic conducted in the Arctic and Antarctic, two areas where isolation is a common occurrence, as well as other extreme environments, such as naval submarines. These studies tend to suffer from the same methodological limitations, however. They may show the gross psychological changes that took place between the time when people entered an isolated environment and when they returned (subclinical depression being the most common symptom), but they do not generally document the detailed fluctuations of mental state that occur during isolation.

"Now, with the advent of notebook computers and refined statistical analysis techniques, we are getting a much clearer picture of what happens to people in long-duration isolation. These data come from various sources. For a little over three years, we have been involved in a collaborative project between the Johnson Space Center and the Australian government's Antarctic Division, in which we study Australian expeditioners while they are stationed in small groups at Antarctic research bases for periods up to 15 months, as well as two 100-day, six-person Antarctic traverses. We share advice and recommendations. My group has also collected information from an Antarctic traverse conducted by a French and Italian group.

"Here at the Johnson Space Center, we have just started collecting data from small crews that spend time in the Life Support Integration Facility. This facility is used for engineering and testing the kinds of life-support systems that would be used on long-duration space missions, such as a manned mission to Mars (including closed-loop systems that recycle water and air). We are studying the people who work on this project while they live with their equipment inside the facility for 30 to 60 days at a time. This sort of study is very important because it allows a comparison with the Antarctic crews. We can begin to explore variations in the motivations of the people in isolated environments and of the stresses they encounter in the different environments.

"From all these studies, we are finding that there is not just a simple decline in psychological well-being over time; many of the changes in mental state occur in response to specific events. It is not just the isolation that does people in--the psychological changes they experience also depend on the emotional baggage that people bring with them, how they interact with the other people with whom they are isolated, what kind of events they experience while isolated, and so on There are tremendous variations among people; two individuals in an Antarctic station at the same time may have extremely different experiences. In fact, the same individual may have vastly different experiences on different expeditions, depending on the events and persons they encounter.

"Ours is operational, rather than basic, research. We will not arrive at universal truths about human nature from these studies. What we will do is come up with some generalizable themes: the kinds of personalities that make up a good crew, the kinds of problems (such as stress) that can be prevented, the kinds of countermeasures that would make life easier for people in isolated settings. It may prove helpful to train people in conflict resolution and in stress reduction and stress management techniques. We want to learn more about how to select for good interpersonal skills. We are studying the benefits of crew autonomy (allowing crews to set their own schedules and activities) and how much support and contact with family and friends people need. We are trying to understand more about leadership abilities. Finally, we are trying to understand more about the complex interactions between remote crews and their at-home management and support personnel.

"The Johnson Space Center is the lead NASA center for isolation studies. It is not a big project and does not involve a lot of money, but the results may be useful in a number of isolated settings: Antarctic bases, lengthy space missions, military outposts and remote oil rigs, for example. Whatever the environment, we are trying to find out how to optimize the comfort and compatibility in a group and to reduce the interpersonal tensions and psychological discomfort that can reduce productivity.

EO Explorer

Global Maps

Notes from the Field

The arctic radiation-cloud-aerosol-surface interaction experiment (arcsix) in greenland.

May 25, 2024 Some 25 of us were up before 6 a.m. to head out on the bus from the hotel to Burlington International Airport to catch the C-130 aircraft, a military transport plane repurposed for NASA fieldwork, to begin our 7-hour flight to Pituffik.

Several mountains of baggage, including scientific instruments and personal luggage, separate us from the less-well-heated economy cabin, which was probably reserved for graduate students, though we are far too collegial a group to check seat assignments. As we head north and east, the landscape out the window is vast, entirely gray-scale, and unforgiving: sea ice with streaks and patches of open water as far as one can see in every direction.

About halfway through the flight, we cross the Arctic Circle. Here the scene is often reduced to pure gray, and one cannot tell what is sea ice, snow, or cloud. This is the challenge we have long faced when attempting to interpret our remote sensing imagery; now, as an early gift of the expedition, I experience it directly.

May 26, 2024

The site is halfway between Washington and Moscow. Most or all of the buildings were prefabricated, brought here by ship in the summer, and mounted on stilts due to the permafrost. Some rough grasses are the only apparent vegetation.

In some ways, the base is well appointed. There is a sports center with an abundance of every conceivable exercise machine, also a tanning machine and a perpetual pool, a huge gym, and a yoga room. There is a recreation center with a movie theater, a lounge area with free apples, tea, and coffee, a game room that is more like an arcade with multiple video machines, and a craft center that has sewing machines (including a state-of-the-art Serger), rock cutting and polishing machines, computer graphics, and printers.

This is a remote place. The site is protected by a thousand kilometers of ice in nearly all directions, and the only ways to get here are by air or by boat for a couple of months of the year, when the sea is not frozen. With full daylight all day and “night,” the times-of-day are marked only by artificial clocks; the natural ones are essentially absent.

May 27, 2024

This was mostly a flight-planning day, getting ready for the first science flight of the campaign. It turned cold, windy, and snow fell today. This was more like what I expected but didn’t experience during the first two days. But now it is sunny again, around 6 p.m., and near-freezing, so there is still standing water on the roadways, and we are past the season when it is safe to walk on the ice-bound bay. The severe environment calls for some specific adaptations.

For example, the outer doors have latches that seal upward, so a bear pushing down on the handle will be unable to open the door. The walkways are made of open steel grids, so snow and mud will drip through. Boots are to be brushed before entering buildings, and plastic boot covers are provided in an effort to limit the amount of dirt that is tracked in.

I took a late-night walk. It’s daylight anyway, though overcast, windy, cold, and flurrying. Pretty much what I expected here.

The power went out twice today. Everything goes down, including the internet. I’m trying to keep everything charged, in case it happens again. Today’s weather represents “Condition Alpha” for storm warnings. That means just be on alert, in case things change. Condition Bravo means you cannot go outdoors without a buddy, or drive alone without a radio. Condition Charlie means you can’t walk out at all; there is a base taxi for urgent movement. Condition Delta: shelter in place.

The pipes are all above-ground because of the freeze-thaw cycle that would destroy the pipes. I guess they must be heated and insulated. They cross the road by going overhead.

Car and truck engines must be heated to avoid freezing and cracking. So, many of the buildings have power cords hanging out in front to run electric engine-block heaters. I didn’t take the last picture quite at midnight, but the scene doesn’t change much during the night.

I think I mentioned that it is mud season here. This is no joke. The place has a very industrial feel, and the only place to walk is on the mud roads. I’ve heard it will get worse as the mud deepens, and mosquitoes come out. Something to look forward to…

May 28, 2024

We had our first flight with the P3 today, and it was far better than I had expected. There was a rare case of cloud-free atmosphere over sea ice in one area north of Greenland where some buoys had been deployed, which allowed for both surface ice and aerosol characterization. Also, a nearly 3-hour run at ~500 feet captured aerosol properties over open water along the northern part of Baffin Bay. Among our objectives are learning the sources and properties of aerosols in the Arctic, their evolution as they age, and their impact on clouds. Others are especially interested in the properties of sea ice as it melts. So, this gives us a start on those objectives.

May 29, 2024

The wind is a force of nature. Today it has been blowing at something like 40 miles per hour, with gusts considerably higher. It literally takes your breath away—and this is just Condition Alpha.

Gusts create the sensation of blowing you away. All this under a relatively clear sky, bright sun, just a few clouds. It is somewhat other-worldly to one who has lived a life at lower latitudes. The temperature is only a few degrees below freezing, but the weather today gives new meaning to the term “wind chill.”

June 1, 2024

Today was an official day off, and in particular, a mental health day for the forecasters. Several of the military folks on the base arranged to take a group of us on a hike over the Greenland Ice Cap. There were 15 of us in five trucks. The trip involved a fair amount of driving on gravel roads in trucks—about half the time driving, half hiking – 5 hours total. The hike itself was about 5 or 6 miles, and we walked around and then on the glacier, though we never did find the Starbucks.

In addition to the stark beauty of the rock fields and ice, the sky is unlike anything we normally see at lower latitudes. The surface is cold, and the atmosphere is no colder (and sometimes is even warmer) than the surface, i.e., it is stably stratified—the “warm” air is already up, so there is not a lot of warm air rising and mixing that typically happens when the surface is heated directly by the Sun.

The glaciers have brought an enormous diversity of stones that litter the ground, and every piece of wood here was carried in from somewhere else. There are little clumps of vegetation, just enough to satisfy the appetites of musk oxen.

So far, I’ve seen Arctic fox (no pictures—they disappeared too quickly), musk ox in the distance, Arctic hare, and snow goose. No polar bears—and no complaints about that.

June 7, 2024

This evening I took a long walk out to the ice-bound pier… AND I SAW AN OTTER!!!

June 4, 2024

The Arctic foxes are molting. They were very cute when their coats were all white. Now they are losing their winter coats and turning brown. I did see a couple of full white coats, but was too slow to get a photo.

June 8, 2024

The project rented a van, and ten of us went off to climb the Dundas, that imposing rock feature not far from the base, though to get there without walking on thin ice (here the term is not merely a metaphor), one has to drive about 30 minutes over rocky and sometimes quite steep roads around the frozen bay.

The angle of repose is the angle a pile of dry sand (or salt) will make if you dump a bucket of it on the ground. It is generally steep (depends in part on the grain size and shape of the sand particles). Dundas is about 725 feet high; it appears to be the remnant of a glacial moraine—rock pushed here by an advancing ice sheet at least that high, that remained after the ice melted away. It is loose sand and rock, mostly gravel and cobble-sized. The climb up was, frankly, arduous, as there are not a lot of footholds.

The first part was steep enough that going on all fours was necessary in places, and the sand and small rocks would slip easily down the slope as one persevered upward. The final part was up a sheer rock wall that was graced, mercifully, with a sturdy rope. My pictures are lacking for the entire traverse, as all my effort went into the climb itself. I did stop part way up the rock wall to check my life insurance policy.

The view from the top was spectacular, but truthfully, there are so many great vistas in this rugged place that the main reward was accomplishing the ascent itself.

The way down was similarly fraught, except that below the rock wall, I had pretty much no choice but to slide down bit by bit—the loose surface material would give way at every step. So, on my back, lift up my rear, slide a few feet using my boots to stop, and repeat. There was some interesting vegetation on the slope—tiny plants and lichen, which I did photograph. I’m told that some of these plants can be hundreds of years old.

In the distance, we saw some dark spots that the binoculars suggested were seals. (Oh, yes—someone here said that my otter from last night was actually a ring seal; not sure that is authoritative, but…).

June 9, 2024

I agreed to join this afternoon’s walk up the edge of the Greenland Ice Sheet.

The slope is moderate by Dundas standards, and the path is completely snow-covered. The walk up is of course uphill, and a steady wind of 30–40 mph (the katabatic wind), with significantly higher gusts, blows off the ice. This guaranteed that however far we got up the ice sheet, we would certainly be able to make it down, either on foot or airborne.

There were pools of water within ice basins at the base. They look a beautiful shade of blue. We saw this in Alaska as well. I think it must be that ice either absorbs all the longer wavelengths, or it preferentially scatters blue, or both. The optics here are stunning, at least to me. Probably because they are unfamiliar.

One way painters provide a sense of distance in a painting is with “atmospherics,” that is, they increasingly blur the edges of more distant objects to account for light scattering by atmospheric gas and aerosols. Mountain climbers experience the opposite, in the thinner atmosphere, remote objects are sharper than they would in everyday experience, so more distant objects appear closer than they actually are. This is true here in Greenland as well, though we are not at a very high elevation along the coast. I expect the phenomenon in this case is due to a very clean atmosphere.

June 11, 2024 Today I got to fly on the P-3. Every satellite scientist should be required to take at least one such flight to see what the Earth is really like. We flew across northern Greenland and over sea ice. In the two weeks since the campaign deployment began, the depth of the sea ice, and the snow upon it, both decreased at those buoys (where it was measured), and, of course, most everywhere else as well.

A field campaign is a layered operation. Aircraft flight scientists build, run, and maintain the twenty or so instruments that measure particle composition, gas concentration, cloud properties, surface reflectivity, and upwelling and downwelling energy. They are awake by 4 a.m. to prepare their instruments for flight, worry about power supplies and calibration, then sit on the plane for six or seven hours, noting what they see from their measurements and out the window.

The number of leads (i.e., openings in the ice) has increased in places. We flew at high elevation to survey the area, measure the overall surface topography and reflectance, and sample aerosol layers aloft, then descended to 300 feet above the ice to capture aerosols emanating from the surface. The photos tell an accessible part of the story. The rest must be teased out of the data in the coming months and years. But my ride is over for now—there is an aerosol forecast due tomorrow.

June 12, 2024

It was flurrying this evening, and my walk carried me down toward the pier. But you might be pleased to know, I did not go all the way; several seals have now been seen on the ice at the pier. My otter or seal in the water was the first anyone saw, and although they say it is relatively rare for bears to go near the base, seals are their primary food. I figured, after a long winter hibernation, a bear might not count me as even a light snack, but in consideration that I had already booked my flight home, I turned around before getting very near the water’s edge.

June 14, 2024

I should say that the food here is okay. Better than I expected. Of course, in such circumstances, it pays to begin with low expectations: hardtack, pemmican, and beef jerky. The cafeteria serves a lot of beef and pork, but there is also chicken, a reasonable salad bar, excellent, fresh bread (the highlight in my opinion), always two of THE three kinds of fruit (apples, oranges, and bananas—so yes, they mix apples and oranges), and of course, Danish, at least in the morning.

In the evening I took a walk, as usual, and ended up in one of the dozens of prefab buildings on the base, with the suggestive label “Heritage Hall.” The door was not locked, and the lights turned on as you entered each room. The place is a sort of museum, a repository for things discarded from the 1950s and 60s.

They have a computer punch-card machine, a vacuum-tube TV set, and a radar scope you will recognize from science-fiction movies. Also some notebooks with photos of the army’s Camp Tuto (now abandoned—only remnants of the airfield remain) and the presumptive city “Camp Century” they built into the ice in the 1950s. The walls flowed at glacial speed but ultimately collapsed.

Thule base was established in 1951, succeeding three waves of Inuit who inhabited the area, apparently beginning 4,500 years ago. The most recent came around 900 CE, met the Norse about 100 years later, and were moved to a new village 60 miles to the north in 1953. There is even a Life Magazine cover showing ships delivering material to the base in September 1952.

Ralph Kahn , an emeritus research scientist at NASA’s Goddard Space Flight Center now at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder, spent three weeks at Pituffik Space Base in northern Greenland in the summer of 2024. He was one of dozens of scientists who participated in ARCSIX ( Arctic Radiation-Cloud Aerosol-Surface Interaction Experiment ), a NASA-sponsored field campaign that made detailed observations of clouds and atmospheric particles to better understand the processes that affect the seasonal melting of Arctic sea ice. These excerpts from his emails home to family provide a glimpse of what life was like on one of the world’s most northern scientific outposts in the world. Photos were taken by Kahn or Gary Banzinger, a NASA videographer who also participated in the campaign. Kahn, an atmospheric scientist, worked with colleagues to provide daily aerosol forecasts that were used to help plan flights.

Tags: aerosols , climate change , clouds , Greenland , ice , NASA , sea ice

This entry was posted on Friday, August 23rd, 2024 at 3:40 pm and is filed under Arctic Radiation Cloud Aerosol Surface Interaction Experiment (ARCSIX) . You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

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SpaceX Polaris Dawn astronauts will conduct high-flying research in Earth orbit

The mission is about more than altitude records and a private spacewalk.

four astronauts in spacesuits with arms crossed and visors up

Update for 9 p.m. ET on Aug. 26: SpaceX has delayed the Polaris Dawn launch until no earlier than Aug. 28 due to a helium leak. Read our story here .

Call it one high leap for astronaut science.

The Polaris Dawn mission, funded by billionaire entrepreneur Jared Isaacman, is scheduled to launch on a SpaceX Falcon 9 rocket no earlier than Tuesday morning (Aug. 27). It has two major operations goals: to perform the first-ever private spacewalk and to fly higher than any crewed spacecraft since the Apollo era, at about 870 miles (1,400 kilometers).

The four-person crew includes Isaacman as commander (who previously funded and commanded the private Inspiration4 orbital mission in 2021); pilot Scott "Kidd" Poteet, a business associate of Isaacman's across several companies; and mission specialists Sarah Gillis and Anna Menon, both of whom are SpaceX engineers.

Polaris Dawn also plans to conduct 40 science experiments, in partnership with 30 institutions worldwide, Menon told reporters during a press conference on Aug. 19. She said there are three categories: human health in areas such as bone density, vision and motion sickness; research about pressure changes to understand how the body reacts to higher-than-usual altitudes; and research undertaken on Earth to see how the astronauts readapt after a few days in space.

Related: How SpaceX's historic Polaris Dawn private spacewalk will work

The crew spent two days in a pressure chamber to test out techniques to make their work more efficient, and to prep for the usual fluid shifts in space that all astronauts encounter: Fluids tend to migrate into the upper body and face and away from the lower body, temporarily creating a "puffy face syndrome" among new arrivals to space.

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The Polaris Dawn astronauts have a set of high-tech gear to track how their bodies will adapt and evolve during their five-day space mission. One is a contact lens that "measures intraocular pressure for extended periods of time," Menon said, referring to changes in the internal pressure of the eye. "We can hope to better understand the mechanisms behind these eye changes; we look into a future where there are hundreds or thousands of people living in space for long durations of time, so it is only a matter of time before there is a medical emergency that requires intervention."

Related: SpaceX Polaris Dawn crew lands at launch site ahead of 1st-ever private spacewalk mission (photos, video)

— Polaris Dawn mission: Meet the crew taking 1st commercial spacewalk

— SpaceX Polaris Dawn private spacewalk mission: Live updates

— How SpaceX's private Polaris Dawn astronauts will attempt the 1st-ever 'all-civilian' spacewalk

The astronauts will also use an endoscope, with a camera attached, that is designed to go into the nostril and examine the airway for inflammation or other factors that may induce "balance issues that astronauts face when they return to a gravity environment."

The astronauts, in fact, have already tested a tool to see how they react to balance issues: a testing device can shoot electricity "between the inner ears to simulate that disorientation and teach more rapid adaptation skills."

More details about the experiments and partners are available on the Polaris Dawn research page (click the logo of each partner to read details about sponsored experiments).

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for Space.com for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, " Why Am I Taller ?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: https://qoto.org/@howellspace

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Celebrating the Milestone of Fusion Ignition

In 2022, Lawrence Livermore National Laboratory made history by demonstrating fusion ignition for the first time in a laboratory setting. Read about the people, facilities, capabilities and decades of tenacity that made this achievement possible.

Read about our fusion breakthrough

Microgravity experiments reveal metallurgical phenomena

(left) An optical image of the solid–liquid interface during the growth of a transparent solid alloy. (right) Four phase-field simulations of the observed phenomena. Due to misoriented grains, cells can invade the neighboring grain, leading to highly convoluted grain boundary shapes (cyan). During the invasion process, a solitary cell can emerge (marked in yellow).

In solidification processing, such as casting, welding, or additive manufacturing, cellular or dendritic patterns develop during the growth of a solid crystal from the liquid phase. In metallurgy, each similarly patterned region is referred to as a grain—which must be controlled during processing as grains affect structural performance. Additionally, the grain texture—the resulting macroscopic distribution of grain orientations and grain boundaries (GBs)—has a key influence on material strength.

To better understand how grains and GBs form and interact with neighboring grains, postdoctoral researcher Younggil Song and international collaborators performed phase-field simulations in coordination with reduced gravity experiments onboard the International Space Station (ISS)—the microgravity conditions on the ISS eliminated flow associated with buoyancy.

For the experiments, the use of a transparent solid alloy enabled characterization of the cell and grain structure, revealing that individual cells from one grain can unexpectedly invade a nearby grain of different misorientation, either as a solitary cell or rows of cells. This invasion process causes grains to interpenetrate each other, and thus grain boundaries adopt highly convoluted shapes. Additionally, it was found that leading invader cells can detach from the original grain and survive for a long time in the neighbor grain as solitary cells.

These observations, published in Nature Communications , were reproduced using the fully 3D phase-field simulation code that Song developed. With this code, researchers were able to model the observed in situ phenomena for the first time. Computational Materials Science Group Leader Robert Rudd says, “This knowledge and the ability to model these processes will open new possibilities for alloy design.”

[ Y. Song , F. L. Mota, D. Tourret, K. Ji, B. Billia, R. Trivedi, N. Bergeon, A. Karma, Cell invasion during competitive growth of polycrystalline solidification patterns , Nature Communications (2023), DOI: 10.1038/s41467-023-37458-0.]

International LZ experiment sees new results in search for dark matter

The nature of dark matter, the invisible substance thought to make up most of the mass in our universe, is one of the greatest mysteries in physics. Using new results from the world’s most sensitive dark matter detector, LUX-ZEPLIN (LZ), an international collaboration that includes Penn State researchers has narrowed down the possible properties of one of the leading candidates for the particles that compose dark matter: weakly interacting massive particles, or WIMPs.

Dark matter , so named because it does not emit, reflect or absorb light, is estimated to make up 85% of the mass in the universe. Although it has never been directly detected, it has left its fingerprints on multiple astronomical observations.

“Dark matter is a fundamental part of the universe; and we wouldn’t exist without it; dark matter’s mass contributes to the gravitational attraction that helps galaxies form and stay together,” said Carmen Carmona-Benitez, associate professor of physics and the LZ principal investigator at Penn State. “LZ is designed to detect cosmic particles passing through earth, including theorized dark matter particles called WIMPs, with great sensitivity. Based on what we detect — and more often, what we don’t detect — we can put additional limits or constraints on the potential characteristics and properties of WIMPs and get a better sense of what exactly these particles are and aren’t.”

LZ, led by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), is located in a cavern nearly one mile underground at the Sanford Underground Research Facility in South Dakota. Researchers at Penn State play a key role in the experiment, contributing to the operation of the detector and the analysis that led to the latest results. The experiment’s new results explore weaker dark matter interactions than ever searched before and further limits what WIMPs could be.

“These are new world-leading constraints by a sizable margin on dark matter and WIMPs,” said Chamkaur Ghag, spokesperson for LZ and a professor at University College London (UCL). He noted that the detector and analysis techniques are performing even better than the collaboration expected. “If WIMPs had been within the region we searched, we’d have been able to robustly say something about them. We know we have the sensitivity and tools to see whether they’re there as we search lower energies and accrue the bulk of this experiment’s lifetime.”

The collaboration found no evidence of WIMPs above a mass of nine gigaelectronvolts per the speed of light in a vacuum squared (GeV/c2). For comparison, the mass of a proton is slightly less than one GeV/c2. The experiment's sensitivity to faint interactions helps researchers reject potential WIMP dark matter models that don't fit the data, leaving significantly fewer places for WIMPs to hide. The new results were presented at two physics conferences on Aug. 26: TeV Particle Astrophysics 2024 in Chicago, Illinois, and LIDINE 2024 in São Paulo, Brazil. A scientific paper will be published in the coming weeks. The results include analysis of 280 days’ worth of data: a new set of 220 days collected between March 2023 and April 2024 combined with 60 earlier days from LZ’s first run. The collaboration plans to collect 1,000 days’ worth of data before the experiment ends in 2028.

“LZ is at least 50 times more sensitive than previous dark matter detectors,” said Luiz de Viveiros, assistant professor of physics at Penn State, whose team is responsible for modeling and monitoring background signals in the detector. “Its sensitivity comes from the many ways the detector can reduce background noise, which are signals that can hide or impersonate a dark matter interaction.”

LZ’s deep underground location shields the detector from cosmic rays coming from space, helping reduce background noise. LZ was also built from thousands of ultraclean, low-radiation parts to reduce natural radiation from everyday objects. The detector is built like an onion, with each layer either blocking outside radiation or tracking particle interactions to rule out dark matter mimics. Additionally, sophisticated new analysis techniques help rule out background interactions.

This result is also the first time that LZ has applied “salting” — a technique that adds fake WIMP signals during data collection.

“By camouflaging the real data until ‘unsalting’ at the very end, researchers can avoid unconscious bias and keep from overly interpreting or changing their analysis,” said David Woodward, former assistant research professor at Penn State, now program manager with LZ at Berkeley Lab.

LZ uses 10 tonnes, or 10,000 kilograms, of liquid xenon to provide a dense, transparent material for dark matter particles to potentially bump into. The hope, the researchers said, is for a WIMP to knock into a xenon nucleus, causing it to move, much like a hit from a cue ball in a game of pool. By collecting the light and electrons emitted during interactions, LZ captures potential WIMP signals alongside other data.

“Researchers have only scratched the surface of what LZ can do,” Carmona-Benitez said. “With the detector’s exceptional sensitivity and advanced analysis techniques, our collaboration is primed to discover dark matter if it exists within the experiment’s reach and to explore other rare physics phenomena.”

The next stage is using these data to look at other interesting and rare physics processes, like rare decays of xenon atoms, neutrino-less double beta decay, boron-8 neutrinos from the sun and other beyond-the-standard-model physics. Future data sets and new analysis techniques will allow the collaboration to look for even lower-mass dark matter.

LZ is a collaboration of roughly 250 scientists from 38 institutions in the United States, United Kingdom, Portugal, Switzerland, South Korea and Australia.

LZ is supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics and the National Energy Research Scientific Computing Center, a DOE Office of Science user facility. LZ is also supported by the Science & Technology Facilities Council of the United Kingdom; the Portuguese Foundation for Science and Technology; the Swiss National Science Foundation, and the Institute for Basic Science, Korea. Over 38 institutions of higher education and advanced research provided support to LZ. The LZ collaboration acknowledges the assistance of the Sanford Underground Research Facility.

Editor’s Note: A version of this release originally appeared at the Berkeley Lab website .

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NOTIFICATIONS

Myths of the nature of science.

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People have ideas about science based on personal experiences, previous education, popular media and peer culture . Many of these ideas are commonly held misconceptions or myths about the nature of science. Here are some of the more common myths that are problematic in science education.

Myth: The scientific method Myth: Experiments are the main route to scientific knowledge Myth: Science and its methods can answer all questions Myth: Science proves ideas Myth: Science ideas are absolute and unchanging Myth: Science is a solitary pursuit Myth: Science is procedural more than creative Myth: Scientists are particularly objective Myth: Scientific conclusions are reviewed by others for accuracy Myth: Acceptance of new scientific knowledge is straightforward Myth: Science models ‘are real’ Myth: A hypothesis is an educated guess Myth: Hypotheses become theories that, in turn, become laws

Myth: The scientific method

Perhaps the most commonly held myth about the nature of science is that there is a universal scientific method, with a common series of steps that scientists follow. The steps usually include defining the problem, forming a hypothesis, making observations, testing the hypothesis, drawing conclusions and reporting results. In classrooms, students can be seen writing up the aim, hypothesis, method, results and conclusion.

In reality there is no single method of science. Scientific inquiry is not a matter of following a set of rules. It is fluid, reflexive, context dependent and unpredictable. Scientists approach and solve problems in lots of different ways using imagination, creativity, prior knowledge and perseverance.

See examples on the Hub

Scientists use a range of research methods:

Producing commercial quanitites of nanofibre
Carbon dioxide and the oceans
Volcanology methods

Myth: Experiments are the main route to scientific knowledge

Experiments are certainly a useful tool in science but they are not the main route to knowledge. True experiments involve a range of carefully controlled procedures accompanied by control and test groups and usually have as a primary goal the establishment of a cause and effect relationship.

Science does involve investigation of some sort, but experiments are just one of many different approaches used. In a number of science disciplines, such as geology, cosmology or medicine, experiments are either not possible, insufficient, unnecessary or unethical, So science also relies on approaches such as basic observations (such as astronomy) and historical exploration (such as paleontology and evolutionary biology.

Scientists use many diverse approaches other than experiments within the broad disciplines of science:

Monitoring kōura
From the smallest bones come the biggest secrets
Date a dinosaur
Developing the New Zealand geologic timescale
Planet hunting

Myth: Science and its methods can answer all questions

Science has achieved many amazing things, but it is not a cure-all for all the problems in society. Although it can provide some insights that may inform debate, science cannot answer ethical, moral, aesthetic, social and metaphysical questions. For instance, science and the resulting technology may be able to clone mammals, but other knowledge is needed (cultural, sociological and philosophical) to decide whether such cloning is moral and ethical. Not all questions can be investigated in a scientific manner.

Myth: Science proves ideas

Popular media often talks about ‘scientific proof’. However, accumulated evidence can never provide absolute proof – it can only ever provide support. A single negative finding, if confirmed, is enough to overturn a scientific hypothesis or theory. Rather than being proven ‘once and for all’, a hallmark of science is that it is subject to revision when new information is presented or when existing information is viewed in a new light.

How a scientific hypothesis or theory can be overturned:

Icebergs and glaciation
Investigating our fern flora origins
Ruffling ancient feathers: kiwi’s Malagasy cousin

Myth: Science ideas are absolute and unchanging

Some ideas in science are so well established and reliable and so well supported by accumulated evidence that they are unlikely to be thrown out, but even these ideas may be modified by new evidence or by the reinterpretation of existing evidence. Science knowledge is durable, but not absolute or fixed – a critical feature of science is that it is self-correcting – so we say that scientific knowledge is tentative. This can be most easily seen at the cutting edge of research and in areas like health and medicine where ideas may change as scientists try to figure out which explanations are the most accurate.

Myth: Science is a solitary pursuit

This myth fits the stereotypical image of a lone scientist working alone in a laboratory. In reality, only rarely does a scientific idea arise in the mind of an individual scientist to be validated by the individual alone and then accepted by the scientific community. The process of science is much more often the result of collaboration of a group of scientists. Most research takes too long, is too expensive and needs more knowledge and expertise than an individual scientist working alone. The Science Learning Hub repeatedly shows this collaboration.

Some more examples:

Dairy research methodologies
Working as a scientist
Collaborating in medical research
Collaborating in science
Science over time: Standing on the shoulders of giants

The activity Scientist introduction encourages students to take a closer look at a scientist’s background and work.

Nature of science

Collaboration is the action of working with someone to produce something and has mutual benefits for both parties. Collaboration can occur between individuals working in a team. It can also describe the way in which individuals or organisations work together on a project. In this case, the collaboration may only be a small part of the individuals’ or organisations’ overall goals and responsibilities.

Myth: Science is procedural more than creative

Many students see science as following a series of steps and being dry, uninspiring and unimaginative. The opposite is true. Creativity is found in all aspects of scientific research, from coming up with a question, creating a research design, interpreting and making sense of findings or looking at old data in new ways. Creativity is absolutely critical to science.

How creativity is critical to science:

The Majestic Samaúma – art meets science
Research design
Creativity and science
Denitrification beds – a creative approach

Myth: Scientists are particularly objective

We often assume scientists are always objective, but scientists do not bring empty heads to their research. Their background knowledge, experiences and the existing concepts they hold mean they can’t be objective. Like all observers, they have a myriad of preconceptions and biases that they will bring to every observation and interpretation they make.

If we confront the world with an empty head, then our experiences will be deservedly meaningless. Experience does not give concepts meaning. If anything, concepts give experience meaning. David Theobald, 1968.

Myth: Scientific conclusions are reviewed by others for accuracy

Limited research funds and time constraints do not allow for professional scientists to be constantly reviewing each other’s experiments. If experiments are repeated, it is usually because a conclusion has been reached that is outside the current paradigm. However, ideas and methods are critiqued before and during publication and acceptance. Ideas and methods are debated and shared in the workplace, at conferences and in scientific journals

Myth: Acceptance of new scientific knowledge is straightforward

The process of building knowledge in science is often portrayed as procedural, routine and unproblematic – leading unambiguously and inevitably to ‘proven science’. The way science investigations and findings are reported can reinforce this myth. However, it is impossible to make all observations relevant to a given situation, for all time – past, present and future – and there is always a creative leap from evidence to scientific knowledge. New interpretations for evidence are not automatically accepted by the scientific community.

A new idea that is not too far from the expectations of scientists working in a particular field would probably be accepted and published in scientific journals, but if the idea appears to be a significant breakthrough or is rather radical, its acceptance is by no means straightforward. Some examples of scientific ideas that were originally rejected because they fell outside the accepted paradigm include the Sun-centred solar system , the germ theory of disease and continental drift .

Myth: Science models ‘are real’

Models are just explanations of perceived representations of reality. A good example is the particle theory of matter , which pictures atoms and molecules as tiny discrete balls that have elastic collisions. This is a model that explains a whole range of phenomena, but no one has actually ever seen these tiny balls. The model is useful and it works as a means to explain and to predict a phenomenon.

Myth: A hypothesis is an educated guess

Everyday use of the word ‘hypothesis’ means an intelligent guess. For science, it can be misunderstood to mean an assumption made before doing an experiment or an idea not yet confirmed by an experiment. A better definition of a hypothesis in science is ‘a tentative explanation for a scientific problem, based on currently accepted scientific understanding and creative thinking’. Hypotheses are supported by lines of evidence and are based on the prior experience, background knowledge and observations of the scientists.

Myth: Hypotheses become theories that, in turn, become laws

Hypothesis, theory and law are three terms that are often confused. This myth says that facts and observations produce hypotheses, which give rise to theories, which, in turn, produce laws if sufficient evidence is amassed – so laws are theories that have been proved true.

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What is solitary flower?

I am Just confused whether solitary means single flower in the whole plant or one flower on one branch of the plant?

$\begingroup$ only 1 flower in 1 inflorescence $\endgroup$ – user25568 Commented Oct 12, 2016 at 5:14

2 Answers 2

Solitary flower means one flower at a specific position of a plant. It usually accompanies with another word either terminal or axillary.

Soliary terminal means a flower present at the apex of the main stem or its branches. e.g. Trillium grandiflorum.

Solitary axillary means a flower arising from the axil of a leaf. e.g. China rose.

Image taken from https://commons.wikimedia.org/wiki/File:China_rose.JPG

No. It doesn't mean that a plant has a single flower.It speaks all about the position of the flower. Think of roses , they are solitary terminals and are in numbers in each plant, always growing at the apices of branches.

Source: My two years of learning Botany as an additional Undergraduate subject.

Short answer :

Solitary flower could be single or many flowers in a branch. How many flower is in a 'branch', That is not the concept of solitary flower. The concept is about 'how many flower is there in an inflorescence (branches specialized for flowers)'

Solitary flower a flower NOT in a "inflorescence" (Cluster of many flowers together). Or in another sense, Solitary flower is an inflorescence made up of only 1 flower.

The complete terminology is: "inflorescence with solitary flower".

Long answer:

To understand what is an inflorescence with solitary flower, you need to look for what is NOT an inflorescence with solitary flower.

User @SanjuktaGhosh gave beautiful examples of solitary flowers, so I gave example of only what is not that.

Brassica inflorescence (Raceme, which is racemose).

(Source http://hasbrouck.asu.edu/imglib/seinet/Brassicaceae/photos/Brassica-nigra-F-web-N1544_tn.jpg ).

Foeniculum sp inflorescence (compound umbel, which is cymose)

(Source: https://upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Foeniculum_vulgare_C.jpg/320px-Foeniculum_vulgare_C.jpg )

We can see now, 'inflorescence' means specialized stem axis/ branches, containing mainly flowers (and some bract leaves). In nature, flowers usually occur in such specialized stems, and look like 'cluster' (many flowers together)

But what if a flower occur NOT in such cluster? rather solitary, at clear distance, and the axis on which flower borne, is not distinctive from the rest plant-body?

We couldn't see any 'inflorescence'; however it is considered as an inflorescence with only 1 flower, and from growth-pattern it is a subset of cymose-inflorescence (since the only-bud is the top-bud of the stem going to be flower)

Reference: what we've been taught College Botany/ VOL-1/ Gangulee, Das, Datta/ New Central Book Agency

$\begingroup$ Feel free to write explanation behind downvote. As well, I gave picture of what is NOT a solitary flower, so that the asker can understand from-where the concept of solitary flower came. $\endgroup$ – user25568 Commented Oct 12, 2016 at 8:34
1 $\begingroup$ Inflorescence itself means a group of flowers arranged on a stalk. So writing "The concept is about 'how many flower is there in an inflorescence (branches specialized for flowers)" is wrong. Besides "only 1 flower in 1 inflorescence" is incorrect.That's why I downvoted your answer. $\endgroup$ – Tyto alba Commented Oct 12, 2016 at 9:56
1 $\begingroup$ Probably you are considering 'Solitary flower could not be an inflorescence'. Have I understood? However, what we've been taught solitary flower as a subtype of cymose or definite inflorescence . The above mentioned textbook says "When the apical or axillary bud forms a single flower, it does not form a real 'inflorescence' but this type is better included within the 'definite' group as further development is limited. In China-rose, the stalk of the flower can be distinguished into a peduncle (axis) part and a pedicel (stalk) part with an articulation between the two". $\endgroup$ – user25568 Commented Oct 12, 2016 at 13:24
$\begingroup$ May be you are right. I've too seen that somewhere. I'll edit my answer after referring to my Studies in Botany. Well I've removed my downvote. $\endgroup$ – Tyto alba Commented Oct 12, 2016 at 13:33
$\begingroup$ Its Ok thank you very much however at any time you feel free to downvote if you found something wrong. However Colg. Bot. kept space that, it is not true-inflorescence where Studies (V1) directly classifies it in cymose. Also thanks for mentioning an example of terminal cyme. I was not aware of that. $\endgroup$ – user25568 Commented Oct 12, 2016 at 13:52

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botany
How many flower is in a 'branch', That is not the concept of solitary flower. The concept is about 'how many flower is there in an inflorescence (branches specialized for flowers)' Solitary flower a flower NOT in a "inflorescence" (Cluster of many flowers together). Or in another sense, Solitary flower is an inflorescence made up of only 1 flower.