Why is the seahorse tail square?

Researchers created a model of the seahorse's tail to examine the advantages provided by its unique structure.

By: Ofir Marom

While most animals have cylindrical tails, the seahorse has a unique tail, with a square cross-section that not only provides the fish with protection thanks to its hard armor, but it also gives the seahorse a strong grip on things like plants, corals or pieces of food floating near its mouth. An article published in the latest issue of the journal Science explains the virtues of the unique tail, details, and provides insights with potential for engineering applications that require a combination of strength and flexibility.

The skeleton of the seahorse tail consists of vertebrae, which look like square rings. Each link consists of four L-shaped plates, placed one on top of the other to form the four corners of the square ring. The spinal cord passes through all the vertebrae. The vertebrae are connected to the spine by groups of muscles, which allow the seahorse tail to twist and grip various objects.

The team of scientists, who have been studying the subject for several years, used advanced XNUMXD printing methods to build a model of a square tail like that of the seahorse, and another similar tail whose vertebrae are circular rings. Both types of models underwent a series of comparative experiments, in which the manner in which they react to different types of external pressure was examined. The laboratory experiments showed that in the square structure of the seahorse tail, the plates that make up each link slide over each other in response to the load applied to them. In this way, improved protection of the spinal cord is obtained compared to the model with the round vertebrae. In addition, it was found that after the pressure was stopped, the plates bounced back, and the vertebrae returned to their original dimensions. The scientists pointed out another advantage of a square tail over a cylindrical tail, in that it allows more points of contact with objects on which it rolls, thus contributing to an improved grip. The insights learned from this research could be very useful for robotics applications that need to be not only robust, but also energy efficient and capable of bending and turning in tight spaces.

Possible future uses could include laparoscopic surgeries that require a flexible but powerful robotic device that can move within organs and bones, as well as search and rescue systems or other industrial uses.