The black piranha (Serrasalmus rhombeus) has been crowned the pound for pound biting champion of the fish world, by Guillermo Ortí, of George Washington University.

The fierce fish ranks high in bite strength among all other vertebrates as well. Its extinct cousin, the "megapirahna" may have put an even bigger hurt on prey in the ancient Amazon basin.

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The black piranha was measured to put up to 320 Newtons (a Newton is a unit measuring kilograms per meter per second squared) behind its razor sharp teeth, according to the study published in Scientific Reports.

The secrets to the piranha's powerful bite are its specially evolved jaw bones and massive muscles. The muscle used to close the fishes' jaws can be up to two percent of the fishes' weight. Imagine a 200-pound man with a pound of beef in each cheek to get the idea of how much muscle that is.

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Ortí scaled up from the black piranha and used fossil measurements to estimate the bite force of the now extinct megapirhana (Megapiranha paranensis). The deadly (but dead) predator could have put up to 4749 Newtons into a bite. That's more than enough to shred flesh and crush bone.

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The bite strength of a great white shark is only one-fourth as strong, adjusting for the size difference.

Photo: The black piranha (Serrasalmus rhombeus). Credit: Corbis