A thing you may not have known: the tail of a seahorse is a square prism rather than the typical cylinder shape normally expected in tails. Researchers have now investigated what mechanical performance advantages this may provide, and reckon it has immense robotic applications.

Clemson University boffins have found the ideal way to fix up robots with flexible steely arms, in a piece published in Science, with the pleasantly explicit title "Why the seahorse tail is square".

While most animal tails are cylindrical, the skeleton of seahorse tails consists of bony armour arranged into several ringlike segments – themselves composed of four L-shaped plates that surround a central vertebra, according to the structured abstract.

These plates are known to articulate with specialised joints that allow them to bend and twist, while remaining capable of resisting vertebral fracture from being crushed.

The boffins wanted to figure out if the square tails gave seahorses any functional advantage.

To determine this, they 3D-printed a model which mimicked the prism of a seahorse tail, as well as a control version which was cylindrical.

Researchers thus "whacked the models with a rubber mallet and twisted and bent them," according to the university's press release.

The square prototype turned out to be stiffer, stronger and more resilient than the circular one when crushed.

It was only about half as able to twist, but this restriction was celebrated as preventing damage to the seahorse. Both prototypes could bend about 90 degrees, the boffins said, although the cylindrical version was slightly less restricted.

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"We haven’t got that far with the applications side of things yet, but we see a lot of potential with this device because it’s so unique," said Michael Porter, assistant prof and the study's lead author.

Porter added that his next step was to build a robot using his tamed seahorse knowledge.

The structured abstract concluded that:

"Understanding the role of mechanics in these prototypes may help engineers to develop future seahorse-inspired technologies that mimic the prehensile and armoured functions of the natural appendage for a variety of applications in robotics, defence systems, or biomedicine." ®