… That piranhas bark? From anecdotes and observational research, scientists have known for a while that red-bellied piranhas make bark-like noises when caught by fishermen. Upon further examination, a team of Belgian scientists found that they make three distinctive types of vocalization in different situations.
In a visual staring contest with another fish, they start making quick calls that sound similar to barks, meant as a warning along the lines of, “Don’t mess with me, buddy.” In the act of actually circling or fighting another fish, piranhas emit low grunts or thud sounds, which researchers believe communicates more of a direct threat to the other fish.
The fish makes these two sounds using its swimbladder, a gas-containing organ that keeps fish afloat. Piranhas contract and relax muscles around the swimbladder to make noises of different frequencies.
The third vocalization? Should the opposing fish not back down, the piranha will gnash its teeth together and chase its rival.
Speaking of teeth: Piranhas are known for their razor-sharp teeth and relentless bite. (The word piranha literally translates to “tooth fish” in the Brazilian language Tupí.) Adults have a single row of interlocking teeth lining the jaw. True piranhas have tricuspid teeth, with a more pronounced middle cuspid or crown, about 4 millimeters tall.
The shape of a piranha’s tooth is frequently compared to that of a blade and is clearly adapted to suit their meat-eating diet. The actual tooth enamel structure is similar to that of sharks.
It’s not uncommon for piranhas to lose teeth throughout their lifetime. But, while sharks replace their teeth individually, piranhas replace teeth in quarters multiple times throughout their lifespan, which reaches up to eight years in captivity. A piranha with half of its lower jaw chompers missing isn’t out of the ordinary.
But don’t worry: The idea that a piranha could rip a human to shreds is probably more legend than fact. For the curious, Popular Science spoke to some experts who estimate that stripping the flesh from a 180-pound human in 5 minutes would require approximately 300 to 500 piranhas. Cases of heart attack and epilepsy that ended with the afflicted drowning in a South American river do show evidence of piranha nibbles, but in those instances, the victim was already deceased when piranhas got involved.
While the myth of the man-eating piranha belongs to movie theaters, the Internet has a wealth of mysterious footage of piranha packs taking down capybaras. Some piranhas do occasionally eat small mammals, but as with humans, it’s usually when the unfortunate animal is already dead or gravely injured.
And just like with humans some piranhas are carnivores and some are vegetarians…
Many years ago I was traveling in Brazil and visited the Pantanal. Just such a stunning place to be. We did a tour over a couple of days and on one day did a river tour in a tiny boat on the lookout for monkeys, ant eaters, otters and many more of the amazing animals you can find in the Brazilian rain-forests. That day we also did some piranha fishing. It freaked me out but at the same time really mesmerized me too. We ate the fish for dinner and the teeth were some kind of a souvenir. Let me tell you: They are indeed racer-sharp!