How many legs does a seahorse have

How the seahorse inspires engineers

Almost all animal tails are round or oval in shape, except for seahorses. Researchers led by Michael Porter from Clemson University in the USA have asked why. The unusual square bone structure hardly helps with swimming, but has other advantages. The team describes what these are in the journal “Science”.

Square and round 3D models

The seahorse's tail consists of 36 square segments that are connected by a spine and joints running down the middle. The research team created simplified models of the angular and one round shape using 3D printers and bent, twisted and pressed them together.

The square shape of the wrap tail proves to be more effective when it comes to gripping and withstanding pressure. On the one hand, the seahorse can hold on to seaweed or coral reefs and wait there until something edible swims past it. On the other hand, the resilient shape makes it difficult for natural enemies such as water birds to catch the marine animal and hold it in their beak.

Seahorse skeleton

In the experiment, Porter's team investigated the mechanics of the models under external pressure. The rectangular components moved with only one degree of freedom when they were pushed together, while the round disks also rotated. When the researchers then twisted the angular model, the individual segments obstructed each other. This restricted the range of motion to half of the round model. In addition, after being twisted, the angular model reverted to its original shape more quickly and with only minimal energy consumption. The researchers suspect this is the reason for the resilience of the angular structure.

When gripping, the team observed that the angular segments formed more contact points with the encompassed surface than the round components and therefore had better adhesion. They also found that the seahorse's tail flexes just as well so that it can grip objects within its field of view.

The findings from the 3D models should lead to a better understanding of biological systems and development processes in nature. However, Porter and colleagues also want to use their results to optimize technical applications: If you increase the dimensions of the square model, you can, for example, construct a gripper arm for robots.