The secret of fish fins and its application for humans

Tiny fishes can make a few flicks with their fins and make themselves turn in circles, dive deep down or even bob to the surface. But how do those fins work?

A new research lead by the University of Colorado at Boulder has studied the engineering behind what makes the fins so strong and yet so flexible. Francois Barthelat, the senior author of the study, already made some studies around the aquarium animals and its surroundings. But the singularity of the fins amazed him, he looked at them and realized that “It’s made of many stiff ‘rays’. Each of those rays can be manipulated individually just like your fingers, but there are 20 or 30 of them in each fin.”. Each ray in a fin is made up of multiple segments of a hard material that stack on top of much softer collagen, making them the perfect balance between bouncy and stiff.

Barthelat and his colleagues used computer simulations and 3D printed materials to go deep into the biomechanics of those structures. The spikes on the fins, include two layers of stiff and mineralized materials called “hemitrichs” that surround an inner layer of spongy collagen. But the layers of hemitrichs aren’t solid. They are like segments, as if someone had cut them in pieces. And those segments can make all the difference.

“All of the segments, essentially, create these tiny hinges along the ray,” Barthelat said. “When you try to compress or pull on those bony layers, they have a very high stiffness. This is critical for the ray to resist and produce hydrodynamic forces that push on water. But if you try to bend individual bony layers, they’re very compliant, and that part is critical for the rays to deform easily from the base muscles.”. His team and he tested the theory by using a 3D printer to produce model fish fins made from plastic. And it worked out great!

BUT WHY STUDY THIS?

The engineering behind the fins and understanding how all work together, can innovate the field of designs for robotic surgical tools, making them flexible when wanted and strong when wanted. On the other hand, the knowledge can also be applied to airplane wings that change their shape with only one button. It would be possible to change the shape of the wings in a continuous manner, in the middle of the air, just like a bird does.

Barthelat says that he and his colleagues have only reached the tip of the iceberg. The wide diversity of fins in the fish world is huge. And also is the knowledge we can obtain from them.

The science behind nature is amazing, and also is the knowledge we obtain from it. We must preserve it to the benefit of the world and also our own.

Source: Science Daily
Complete Study: https://www.science.org/doi/10.1126/scirobotics.abf9710

Author: Bernardo Andrade