Mantis shrimp's claw inspires stronger body armor and implants
Peacock mantis shrimps are tough creatures. They are often found living alone, perhaps a result of their highly combative nature and aggressive hunting strategies, which, when combined with their super-durable claws, make them formidable predators.
Now, researchers are taking cues from the woven mineral structures that give the mantis shrimp's punch such power to inspire the creation of ceramics for medical or military use.
The mantis shrimp's club-like arms can deliver a strike with force 100 times its weight that moves at the speed of a rifle bullet, which proves to be good for inflicting damage on mollusk shells, crab exoskeletons, the skulls of small fish, and sometimes even the occasional unlucky fisherman. The punch accelerates so quickly, it boils the water surrounding it, creating a second punch of bubbles that targets prey.
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"What makes [mantis shrimp claws] so incredible is that they're stiff and they're also tough, which is really kind of an inverse relationship in materials science," said study researcher David Kisailus, a materials scientist at the University of California, Riverside, reports Mother Nature Network.
Mantis shrimp are able to deliver these blows without fracturing their own club because of the highly organized thin layers within their claws, which include a natural polymer that acts similarly to tooth enamel to fill in potential cracks.
"We were impressed that this guy can impact its prey tens of thousands of times over a period of three to four months without breaking its own hand," said David Kisailus, who runs the lab at University of California Riverside that is studying the crustaceans, according to the Los Angeles Times.
To determine how the animals perform these feats, an international team of scientists examined the structures of the claw at the nanoscale and found three separate layers that allow the mantis shrimp to repeatedly rain blows on prey.
When the mantis shrimp winds up to punch, its claw folds into a club five times thicker than the rest of its appendages, with three distinct layers. The outer impact region, or striking surface, is mostly made up of a mineral called hydroxyapatite, a substance containing calcium that gives human bones and teeth their rigidity.
Beneath this thin layer in the center of the club lies a lattice-like matrix of chitosan, which supports the striking surface and absorbs impact, reducing the possibility of any cracks spreading. Finally, a third layer of chitin fibers wraps around the club and compresses the claw, stopping fractures the way tape on a boxer's hand might.
Researchers say their work may provide a "nature-inspired blueprint to design biocompatible implants" or stronger body armor.
"The highly damage resistant property of the mantis shrimp could be most useful in medical products such as hip and joint implants, as they sustain impacts hundreds of times daily during walking and daily activities," said Assistant Professor Ali Miserez, from Nanyang Technological University School of Materials Science Engineering and School of Biological Sciences.
Further research could lead to products based on the composition of the mantis shrimp's claw that are lighter weight yet able to withstand consistent use or repeated blows.
"The insights gained from natural materials...may find application in armor plating, where alternating layers of high- and low-modulus materials may enhance material toughness," wrote K. Elizabeth Tanner in a companion piece that accompanied the study in the journal Science.
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