# What do a jellyfish, a cat, a snake, and an astronaut have in common?

Have you ever watched a snake slither or seen a cat twist in mid-air to land on its feet?

Both of these animals move without the need for legs or wings.

How do they do it? The answer lies in the way they change their shapes.

A recent study led by a team from Caltech, including the expert Peter Schröder, found that there’s a basic math principle that explains this.

At a big conference called SIGGRAPH in Los Angeles, the researchers shared that many animals and even humans in special situations (like astronauts in space) move by altering their body shapes.

Imagine a single-cell organism, super tiny, moving around. It doesn’t have tiny legs or wings. All it can do is change its shape to move.

Astronauts, when they’re floating in space without any surface to push off from, turn around by making dance-like motions. This changes their body shape and lets them turn any direction they want.

Now, let’s understand the math bit but in a simple way. Schröder from Caltech talks about a concept called the “principle of least dissipation”.

This fancy term just means that in nature, things try to move in the most efficient, or easiest, way possible.

Think of ice skating. If you’ve ever seen someone ice skate, you know they push their feet to the sides to move forward.

Why? Because it’s hard for the skates to slide side-to-side, but easy for them to glide forward. So, the easiest and most energy-saving way for skaters to move is forward.

In the same way, snakes find it easier to move forward than side to side. When they wiggle their body side-to-side, it would use up a lot of energy due to the ground rubbing against them. But, if they move forward while wiggling, it’s smoother and saves energy. That’s why snakes slither forward as they wiggle.

To test this math idea, the team used computers to create digital models of these animals. They used the “principle of least dissipation” to see how these digital animals would move. And guess what? The computer-generated movements were very close to how real animals move!

In simple words, Schröder and his team found a straightforward math rule that explains how many creatures, from tiny cells to big cats and even humans in space, move. It’s all about changing shape in the most efficient way possible.

Schröder excitedly shares, “There’s something beautiful about finding a simple rule that explains so many different movements. That’s what drives me in my work.”

The team’s discoveries are detailed in a paper called “Motion from Shape Change”. The study also had contributions from Yousuf Soliman, a student at Caltech, and several experts from the Technical University of Berlin.