South American arapaima fish has scales that resist piranha bites

Engineers could take a lesson from the fish while designing body armor.
Posted By Evan Bleier  |  Oct. 25, 2013 at 12:39 PM
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(UPI) -- The natural body armor of the South American arapaima fish is so tough that it can withstand the piercingly fierce bite of a piranha without a problem.

With its streamlined body and flat head, the arapaima certainly looks strong. The fish can grow to more than six feet long and weigh as much as 440 pounds.

University of California scientist Marc Meyers tested the arapaima’s toughness by mounting some of the fish’s scales on a rubbery surface meant to simulate flesh, and then attacked them with piranha teeth attached to an industrial-strength hole-puncher. The teeth barely penetrated the scales and cracked before they reached the rubber.

“It’s how body armor should be made,” said Robert Ritchie from the Lawrence Berkeley National Laboratory, who is working with Meyers in studying the arapaima. “If it was just the hard shell, the thing would shatter.”

According to Ritchie, the structure of the arapaima’s scales could be an inspiration to human engineers. “Lightweight body armor is something everyone wants,” he says. “The Kevlar armor our troops get is extremely heavy and many people don’t bother wearing them. But nature does it very well.”

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