Bark Worse than Their Bite?

If you mention the word piranha to people, images of razor-sharp teeth and ferocious feeding frenzies are pretty much the norm. These fish have been showcased in films and media as fierce meat-eating machines that will attack in a moment’s notice! And like most monstrous myths, that is quite an exaggeration from the truth.

Red-bellied piranah (via WikiCommons)

Most piranhas, including the red-bellied piranha (Pygocentrus nattereri) featured at the New England Aquarium, aren’t out looking for a nice human to eat. Instead, they eat small worms, insects or fish, all items they can find throughout the Amazon River Basin. And while many times there is an abundance of food, sometimes there is competition between these fish for a snack! And how do they tell the other fish to back off? They bark!

Those are some teeth!

Researchers in Belgium wanted to look closer at the strange noises that piranhas make when the fish were picked up or caught in a net. They suspended a hydrophone into a tank containing piranhas and recorded any sounds made and documented what the fish were doing at the time. And for the most part, the fish were silent and pretty chilled out. However, when food was introduced, it was a different, and very noisy story! [Here's a link to the abstract of this study.]

The first noise the researchers documented was a bark-like noise. When two fish swam directly at each other, it sounded like a dog park: barking everywhere! The researches interpreted this as a warning signal between the dueling fish, with the goal of trying to intimidate the opponent. But it didn’t stop there! In addition to the barking, researchers observed the fish making drum-like percussive sounds when the piranhas were fighting for food as well as a “croaking” sound when the fish would snap their jaws at each other. So when no food is around? It’s quiet. When there’s food around, piranhas are quite loud! National Geographic has posted a video where you can hear some of these noises.


Wonder if he speaks piranha...

So come visit our Freshwater Gallery located on the third level of the Aquarium. Our red-bellied piranhas are usually calm and collected. But if you catch a feeding session and you just may just get a lot more bark for the bite!

-Jo

[Jo is part of the Aquarium's Visitor Education team. She just returned to Boston after spending several weeks in South Africa working with African penguin rescue efforts. Read her posts about the experience. She also traveled to Antarctica in 2013 and took some amazing pictures.]