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Megapiranha was real and it could bite harder than a T. rex

Illustration for article titled Megapiranha was real and it could bite harder than a T. rex

Yes, it sounds like the name of an awful horror knockoff (this one, to be exact), but a 22-pound beast known as Megapiranha paranensis once roamed the water 10 million years ago, and its bite was truly something to fear.


An international team of researchers recently provided some of the first authoritative calculations of how hard modern piranhas can bite, something that's easy to estimate but hard to actually measure. Indeed, if you want to really know for certain how hard a piranha can bite, you've got to head into their waters, try to fish one out, then hold it by the tail and then present it with the plates of a gauge that can measure its force.

Only once it bites down on those plates do you have an accurate measurement of its bite — and while it's a myth that piranhas go around in swarms devouring any humans that cross their path, that's still not especially pleasant work. But from that data, researchers have determined that the largest living piranha, the 2.5-pound black piranha, can bite with a force of 72 pounds, or 30 times its body weight.


Here's where the good old phrase "for its size" has to do some heavy lifting. While other predators have fiercer bites in absolute terms, nothing really comes close to the piranha in relative terms. American alligators, for instance, can only bite with about 10 times the force of their body weight, meaning the black piranha has a bite three times harder. Even Tyrannosaurs rex, the most infamous predator in Earth's history, could "only" bite with 3,000 pounds of force, which sounds impressive until you remember they generally weighed around 15,000 pounds.

Based on analysis of megapiranha bones, their bite force could have been anywhere from 280 to 1,070 pounds — potentially as much as 50 times their body weight. Megapiranha's chompers were even more brutally effective than that of its smaller, living relatives, as it could both tear through tissue and crack thick shells and bones. We don't know exactly what it ate, but it clearly lived at a time when some gigantic prey was available for the eating, as study co-author Stephanie Crofts of the University of Washington explains:

"If our calculations are correct, Megapiranha was probably a bone-crushing predator taking bites of anything and everything. We found the Megapiranha teeth had the same maximum strength like you saw in regular piranha, but then the patterns of stress distribution within the tooth was also similar to fish able to eat hard-prey."

You can read the entire original paper at Science Reports.

Image of modern piranha by Instant Vantage on Flickr.


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These bite comparisons would be more interesting if they compared force per tooth surface because that is what matters when you bite something. If the total force is spread out over a large surface area, the bite is much less functionally than if the surface area is small. Given the relative size of the jaws/teeth of a T-Rex and a megapiranha, the 1000 lbs of bite force of a megapiranha would be much greater per surface area of tooth than the 3000 lbs of a T-rex. The total body size and weight is irreleveant- it is tooth surface area that counts for biting.