Mantis shrimps punch with the force of a bullet - and now we know how
18 October 2018
By Leah Crane
The mantis shrimp packs a mean punch, smashing its victims’ shells with the force of a .22 caliber bullet. But that’s not because it has particularly powerful muscles – instead of big biceps, it has arms that are naturally spring-loaded, allowing it to swing its fistlike clubs to speeds up to 23 metres per second.
We know that the key part of a mantis shrimp’s punch is a saddle-shaped structure on the arm just above the shrimp’s club. This shape works a bit like a bow and arrow, says Ali Miserez at Nanyang Technological University in Singapore: the muscles pull on the saddle to bend it like an archer’s bow, and when it is released that energy transfers into the club.
Miserez and his colleagues used a series of tiny pokes and prods, as well as a computer model, to examine exactly how the shrimp’s saddle holds all that energy without snapping. They found that it works because of a two-layer structure. The top layer is made of a ceramic material similar to bone, and the bottom is made of mostly plastic-like biopolymers.
When the saddle is bent, the top layer gets compressed and the bottom layer is stretched. The ceramic can hold a lot of energy when it is compressed, but is brittle when bent and stretched. The biopolymers are stronger and stretchier, so they hold the whole thing together.
More:
https://www.newscientist.com/article/2182882-mantis-shrimps-punch-with-the-force-of-a-bullet-and-now-we-know-how/
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