Mantis shrimp becomes model for military armor

Any chance to write about shrimp seems like one worth taking, and now scientists are learning from one of the most interesting ones out there: the peacock mantis shrimp, whose "hammer" is being studied to improve human armor.

The sea creature, which isn't actually a shrimp, has a "hammer" arm that it uses for hunting shelled-creatures. That arm can deliver an impact the force of a .22-caliber bullet.

Researchers at the University of California Riverside analyzed the materials making up the arm to discover why the arm itself didn't crack upon impact with hard surfaces.

"This club isn't just one uniform, composite material," said study co-author David Kisailus. "It actually consists of three separate regions that together make the club stiff and also fracture tough, which are two inversely related properties."

A closer look, using an x-ray, found that the arm is made of the mineral hydroxyapatite, which is the calcium compound that makes up our bones.

Almost more important than the make-up of the arm is the design of it: it has a spiral shape, akin to the shape of DNA, that absorbs shocks. Since the mantis shrimp molts, it only needs to last until it's replaced.

"Because the fibres are arranged in this helicoidal architecture, those cracks will have to propagate a very long distance to escape the club - and they never do," Kisailus said.

Lastly, the arms are wrapped in chitin, which puts the whole thing under strong compression that helps redirect the shockwaves it sustains.

Using this information, researchers are attempting to create armor. Preliminary designs have shown that cheaper, lighter armor is a very real possibility.

"We've taken them out to the desert and tried to shoot them with different munitions, including high velocity rounds," Kisailus said. "Interestingly, our composite materials completely stopped these rounds."

Watch the hammer in action below.

Via Science Fare

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