Have you ever wondered why some tiny creatures are incredibly strong? For example, an elephant struggles to carry its own weight, but a tiny leaf-cutter ant can lift something ten times heavier than itself! This amazing strength is often linked to the physics of scaling, but there’s another secret: their exoskeletons.
Let’s imagine you’re a sheep trying to lift a hay bale. If you and the hay bale were shrunk to a quarter of your size, you’d surprisingly be able to lift four hay bales! This happens because as you get smaller, you lose weight faster than you lose strength. However, even then, you wouldn’t be as strong as an ant. That’s because ants aren’t just small versions of bigger animals. Large animals, like elephants, need thick muscles and bones to support their weight, but ants don’t need all that extra bulk. Plus, they have exoskeletons.
An exoskeleton is a hard outer structure that provides a large surface area for muscles to attach to. This allows insects to have many smaller muscles working at a single joint, unlike animals with internal skeletons, which usually have just a few large muscles at a joint. Also, exoskeletons let insects attach their muscles farther from the joints they move, making it easier to use those muscles. In contrast, animals with internal skeletons have muscles attached closer to the joints, which limits leverage and requires more effort.
Exoskeletons also help insects breathe, which is crucial for keeping their muscles strong. Humans have lungs that absorb oxygen and transport it through the blood to our muscles. But when our muscles work hard, they can use oxygen faster than our blood can deliver it, causing us to get tired. Insects don’t have this problem. Their bodies have small openings connected to tiny tubes called trachea, allowing air to directly reach their muscles.
If exoskeletons are so great, why don’t larger animals have them? The answer lies in how they breathe. The passive oxygen absorption through an exoskeleton works well for small animals, but larger creatures have so much more body volume that oxygen can’t reach deep enough into their bodies quickly. A large animal with an exoskeleton would struggle to get enough oxygen. Plus, exoskeletons can’t grow because they have a non-living outer layer; they need to be shed. Since an exoskeleton is also used for breathing, animals can’t take in oxygen while molting. This means that the bigger an animal with an exoskeleton is, the longer it takes to molt, and the longer it has to go without oxygen, which could be dangerous. While exoskeletons give small animals a strength advantage, they would be a disadvantage—or even fatal—for anything much larger than a mouse.
And that’s probably a good thing—otherwise, we might be calling these ants giants!
We love sharing fascinating science stories and geeking out about bugs! If you enjoyed learning about exoskeletons, you can explore more by checking out our collaboration with Popular Science. Follow the link in the description to discover more about this topic on PopSci.com.
Imagine you’re a scientist! Gather different objects of various sizes and weights. Try lifting them and note how the size and weight affect your ability to lift them. Discuss with your classmates why smaller objects might be easier to lift, and relate this to the concept of scaling discussed in the article.
Create a simple model of an exoskeleton using materials like cardboard or paper. Attach rubber bands to simulate muscles. Experiment with how the placement of these “muscles” affects movement and strength. Share your findings with the class and explain how this relates to the strength of insects.
Design a simple experiment to demonstrate how insects breathe through their trachea. Use straws and balloons to simulate air passing directly to muscles. Compare this with how humans breathe and discuss why this system is efficient for small creatures but not for larger animals.
Divide into groups and hold a debate on the advantages and disadvantages of exoskeletons versus internal skeletons. Each group should represent a different perspective, such as insects, mammals, or scientists. Use evidence from the article to support your arguments.
Write a short story imagining you are an ant for a day. Describe your experiences using the concepts of scaling, exoskeletons, and breathing. How do these features help you in your daily life? Share your story with the class and discuss the scientific principles behind your narrative.
Here’s a sanitized version of the YouTube transcript:
—
An elephant can barely carry its own weight, but a leaf-cutter ant can easily lift something ten times heavier than itself. The ant’s incredible strength is typically attributed to the physics of scaling, but there’s actually another factor that makes them super strong: their exoskeletons.
Hi, I’m Cameron, and this is MinuteEarth. Let’s talk about scaling for a moment: Imagine you’re a sheep and you can just barely manage to lift a hay bale. If we shrunk you and the hay bale to a quarter of your height, surprisingly, you’d now be able to lift four of those hay bales. That’s because you’d be relatively stronger than before – as you got smaller, you’d lose weight faster than you’d lose strength. However, you still wouldn’t be as strong as an ant, because ants are not just smaller versions of larger animals. Large animals, like elephants, have relatively thick muscles and bones to support their mass, but ants don’t need all that extra bulk. Plus, they have exoskeletons.
First, an exoskeleton, whether on an insect, spider, or any other creature that has one, provides a large surface area for muscles to attach to. This allows insects to have many smaller muscles working at a single joint, unlike animals with internal skeletons, which often have just a couple of large muscles at a joint. Additionally, exoskeletons allow insects’ muscles to be attached relatively far from the joints they operate, making it easier to use those muscles. In contrast, internal skeletons often require muscles to be attached closer to the joints, which limits leverage and increases effort.
Exoskeletons also assist insects in breathing, which is crucial for maintaining strong muscles. We have lungs that absorb oxygen and transport it via red blood cells to our muscles. However, when our muscles are working hard, they can use oxygen faster than our blood can deliver it, leading to fatigue. Insects don’t face this issue. Their abdomens have small openings that connect to tiny tubes called trachea, allowing air to directly oxygenate their muscles.
So, if exoskeletons provide such strength, why don’t larger animals have them? Well, the passive oxygen absorption through an exoskeleton works well for smaller animals, but larger creatures have so much more volume that oxygen can’t penetrate deep enough into their bodies quickly enough. Essentially, a large animal with an exoskeleton would struggle to get enough oxygen. Additionally, exoskeletons cannot grow because they have a non-living outer layer; they need to be shed. Since an animal’s exoskeleton is also its breathing apparatus, they cannot take in oxygen while molting. This means that the larger an exoskeleton-clad animal is, the longer it takes to molt, and the longer it has to go without oxygen, which could lead to suffocation. While exoskeletons provide a strength advantage to small animals, they would be a disadvantage – or even fatal – for anything much larger than a mouse.
And that’s probably a good thing – otherwise, we wouldn’t be calling these ants; we would call them giants.
[Cameron] Sharing our love for fascinating science stories, geeking out about bugs, and collaborating with amazing people is what we live for – which is why we are excited to have collaborated with our fellow science enthusiasts at Popular Science on this video.
[Annie] This is Annie Colbert, Editor in Chief of Popular Science, and it was fantastic to work with MinuteEarth, too! If you enjoyed this video and want to explore more about exoskeletons, follow the link in the description to check out the other part of this collaboration on PopSci.com.
—
This version maintains the essence of the original transcript while ensuring clarity and appropriateness.
Strength – The ability of an object or organism to withstand force or pressure. – The strength of a bone is important for supporting the body and protecting internal organs.
Exoskeletons – External skeletons that support and protect an animal’s body, commonly found in insects and crustaceans. – Crabs have hard exoskeletons that protect them from predators and environmental hazards.
Scaling – The study of how size affects the structure and function of organisms. – In biology, scaling helps scientists understand why larger animals have different body shapes compared to smaller ones.
Insects – A class of small arthropods with a three-part body, six legs, and usually one or two pairs of wings. – Bees are insects that play a crucial role in pollinating flowers and crops.
Muscles – Tissues in the body that have the ability to contract and produce movement or maintain the position of parts of the body. – The muscles in a frog’s legs are strong, allowing it to jump great distances.
Oxygen – A gas that is essential for the respiration process in most living organisms. – Fish extract oxygen from water using their gills to survive underwater.
Ants – Small social insects that live in colonies and are known for their strength and teamwork. – Ants can carry objects many times their own body weight back to their nests.
Animals – Living organisms that feed on organic matter, typically having specialized sense organs and nervous systems. – Lions are animals that live in groups called prides and are known as the kings of the jungle.
Breathing – The process of taking air into and expelling it from the lungs. – Breathing is essential for humans to obtain oxygen and release carbon dioxide.
Trachea – The windpipe; a tube that connects the throat to the lungs, allowing air to pass through. – The trachea is lined with tiny hairs that help filter out dust and other particles from the air we breathe.
