Military Excited About Peacock Mantis Shrimp's Fists of Fury
The Peacock Mantis Shrimp
The peacock mantis shrimp, neither a praying mantis or even a true shrimp and certainly not a peacock, has drawn the interest of the military because of the power of its tiny fists of fury which can punch holes through clam shells. As an indication of their interest in this crustacean that is closely related to shrimp, the Air Force Office of Scientific Research awarded $600,000 to scientists at the University of California, Riverside to study the mantis shrimp for possible military applications-- specifically, how to replicate its fists' lightweight, impact-resistant qualities to make stronger, lighter armor.
The four- to six-inch long tropical crustacean, or more specifically stomatopod, is colorful like a peacock, looks like a shrimp and has a “mantis-like” feeding strike. When it strikes with its dactyl clubs, or “hammer fists”, it unleashes its awesome power in repeated one-two fashion. One: its 5-mm wide fist accelerates faster than a .22-caliber bullet and strikes with 200 pounds of force. Two: the acceleration is so fast that cavitation occurs-- the water boils creating tiny bubbles that implode against the victim, inflicting further damage. So powerful are these strikes, that in a matter of seconds a peacock mantis shrimp can pulverize mollusk shells. They must be kept in acrylic aquariums because they can literally smash through glass. See the video below to watch (and hear) the peacock mantis shrimp punching into a clam. According to David Kisailus, who runs the lab at the university, “they push their prey up against a rock and start beating on it until their shells crack open”. There is a reason fishermen call them “thumb-splitters”. Another researcher, biologist Roy Caldwell, says that in 30 years he has been battered many times by the peacock mantis shrimp, sometimes resulting in deep and serious wounds, though he hasn't yet lost any appendages.
Fists Good For 50,000 Strikes
What's aroused the military, though, is the fact that these strikes do not damage the fists. It takes months and up to 50,000 strikes before a fist is broken and a new one must be grown. The Air Force wants David Kisailus to further his investigations of how the creature's fists can withstand such punishment without destroying themselves and, with this knowledge, create lighter and stronger armor.
It turns out the hammer fist is a composite weapon, with three layers performing complex interactions during a strike. There is an outer layer made up of a crystalline form of calcium phosphate that can withstand massive compressive forces, an inner layer of softer, spiraling fibers reinforced by a mineral material which absorbs impact energy and prevents cracking, and finally another layer of fibers which wraps around the fist (like a boxer's taped fists), which prevents any fractures from spreading.
Kisailus' team have made a prototype using epoxy and fiberglass based on the biology of the peacock mantis shrimp's fist's inner layer only. The resulting material, one foot square by less than an inch thick and lighter than steel armor have stopped high-velocity rounds, flattening the bullets as the energy from the impact dissipated throughout the material. With further research over the next two or three years, Kisailus hopes to improve its resistance and make it much lighter, perhaps by incorporating structures and substances mimicking the fist's other layers and using carbon fibers.
Armor and Cavitation Protection
There are many uses for such armor, from humvees to helmets to aircraft-- particularly low-level aircraft used in close-ground support such as helicopters and A-10 Thunderbolts that receive enemy ground fire. The material might also be used structurally because of its strength and light weight. Research into the cavitation resistance of the creature's fist strike could also yield improvements in how to prevent cavitation damage to ship's propellers. Kisailus is also seeking $170,000 from the Office of Naval Research, but has not yet received a response.
It would, however, be nice if the creature's ability to regenerate broken and ruined limbs received as much attention.
© 2012 David Hunt
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