Discover the podcast behind this transcription in Science or Fiction. © Futura
First question: what exactly are piranhas? You’re going to tell me it’s a fish. It’s not wrong, but it’s not completely true.
Who are piranhas?
In fact, the word piranha (or [« piragna »]) refers to several species of fish. Even if they are grouped under a name which literally means “devil fish”, there are no less than 80 species, some of which feed on fruits, seeds and other plants. Of course, there are also a whole host of carnivorous species, which are particularly attracted to the smell of blood. These species feed mainly on insects, molluscs, rodents or even snakes, and also fish, even other piranhas! Yeah, they’re a bit cannibalistic our piranhas on top of that. Besides, a little vocabulary point that will serve us later. Cannibalism is the act of consuming, in whole or in part, an individual of one’s own species. So here we are exactly in this case. But do you know what cannibalism is? It is the eating of human beings. I allow myself to make the distinction because these are two notions that are sometimes confused and yet very different. And since we wonder if piranhas eat humans, so if they are cannibals, I preferred to be clear.
But hey, we’ll come back to that in a moment. Piranhas can also eat much larger animals for dinner if they are sick or injured. In short, they eat everything, they are not too picky. In terms of geographical distribution, if you find yourself at the beach this summer, don’t worry since these fish are endemic to the fresh waters of South America. They are only found there.
A terrifying reputation
Anyway, what earns them their bad reputation, just like sharks, is that they are said to be voracious and extremely ferocious, and that they could even devour everything believed a human, and this, in just a few minutes! So it’s true that when you watch videos of piranhas violently attacking chicken legs immersed in water, there is cause for concern. It’s really terrifying, but is it representative of reality? Their hunting techniques are not as frantic and bloodthirsty as one would think.
In fact, these fish will react to noises and vibrations produced by splashing, which can mean that an animal is dying in the water. And since they’re attacking carcasses, they’ll quickly move in that direction. As mentioned, they are also attracted to the smell of blood, which will lead them in the direction of an injured animal, another ideal target for these opportunists. But, ultimately, they will not, or very little, attack living and healthy animals. If they attack, in these cases, it is by measure of prevention or defense.
Afterwards, be aware that these fish are quickly annoyed by the dry season, and that they can therefore be particularly aggressive during these periods. This for a fairly obvious reason: these seasons dry up the water points where they live, forcing them to gather in very large numbers in very small spaces, all with very little food. Inevitably, as soon as the slightest prey passes by, they all throw themselves on it! Yeah, but suddenly, what happens when a human walks near their home?
Humans versus piranhas
Well, I assure you: even when they are pissed off, there is almost no chance that the piranhas will jump at your throat. To give you a little statistic, no fatal piranha attack has been reported since 1870. What happened? It’s a good question, because to get nibbled by a fish, you have to go there already! But, indeed, in the 1870s, there was a group of piranha attacks that caused a lot of talk, and it is even certainly because of this affair that the belief was born.
At that time, in Brazil, it was the war against Paraguay. Who says war says wounded, and therefore many soldiers who wanted to try to be treated. For that, they had to walk for a long time and cross the Rio Paraguay river, except that… they never reached the opposite bank. The weakened soldiers ended up devoured by piranhas, attracted by the smell of blood. This spine-chilling story was subsequently widely taken up by the cinema, which did not fail to amplify it by giving surreal dimensions to these fish, which thus almost become a werewolf of the rivers. A bit excessive, isn’t it? Especially since, as we said, since this famous attack in 1870, no more fatal attacks have been recorded!
On the other hand, it is true that it can happen to be bitten. For example, in 2013, about sixty people were attacked by a school of piranhas on a beach in Argentina, near the Parana River. The victims had not seen the fish, due to the murky water that day. Some people then felt bites on their feet, hands, and some even had pieces of flesh torn off!
It’s really repulsive. A poor 7-year-old girl even had to have a finger amputated that day… So, it’s really scary, but in fact, these phenomena are extremely rare. Moreover, the inhabitants of South America settled near the rivers where different species of piranhas live, explained that they generally bathe without problem, even in the presence of these fish. And for good reason, the risk of being attacked, for a healthy human, is minimal. On the other hand, if there is something to be wary of in these rivers or lakes, it is caimans, freshwater sharks or even eels and anacondas! All these animals, overall, it is better not to cross their path.
Different species you can be wary of (just in case…)
But hey, because it’s better to be careful, I’m going to give you a little list of piranhas to watch out for, so you can avoid having your calves crunched during a potential trip to South America. South ! Let’s get started, let’s talk a little about the black piranha. These fish do not necessarily live in schools, they are rather solitary, and fortunately because their jaws are one of the most powerful of all animals, compared to their size! Yes yes, you heard right, this piranha has about thirty times its body weight to bite, so better keep its toes safe.
The next species scares me a little, personally. The red-bellied piranha is probably the best-known representative of these carnivorous fish! As its name suggests, its belly turns red during the breeding season. Unlike its cousin the black piranha, this species prefers to live in groups, and is the source of impressive bites. In particular, there have been several cases of swimmers or fishermen whose finger or toe had been severed! Yes, there it is, so not that great either.
Come on, let’s try another one to see? The Sao Francisco piranha, a species that lives in Brazil, is considered one of the most dangerous. It’s funny, I have the impression that we’ve only been saying that for a while now. Yes, but there, these fish are squarely nicknamed in English the man eating piranhas, which in French means “man-eating piranhas”. Well that’s great, for our good old received idea that says piranhas eat humans… Yes, except that in fact, it won’t devour you any more than another. Anyway, be careful, huh! Like the others, he can bite you just fine, especially since he is about 50 cm long! And precisely, he too lives in a group.
Well, it’s true that all that suggests that, yes, piranhas are terrible human eaters, but in reality, not really! Apart from this dark affair of 1870, there have never been other stories of its kind. So of course, you can still get chewed up during a trip to the Amazon, because yes, piranhas are still wild animals. But if you avoid venturing too far into their territory, don’t worry, they won’t jump out of the water to attack you.
