Separating Myth from Reality With Piranhas

Piranhas are among the most terrifying aquatic animals on the planet, right up there with sharks, crocodiles, and the fish some think can swim up a stream of urine if you pee in the Amazon. This is mainly because of the widely-held belief that a school of hungry piranhas could quickly strip you of all your flesh and bones. While this may have some basis in reality, it certainly doesn’t address the question of whether or not piranhas pose any real threat to humans. (By the way, every year in the US, there are an average of 2.18 fatalities caused by vending machines and 0.6 fatalities caused by shark attacks, making the former approximately four times more likely to kill an American than the latter.)

The first thing to know is that piranhas aren’t dangerous to humans. There are many accounts of people swimming in water that were teeming with these fish and nothing bad happened. To back up his claim, one Dr. Herbert Axelrod bravely dived into a pool teeming with red-bellied piranhas—the most hazardous species—wearing only swim shorts. To make it even more unbelievable, he even had some fresh, red meat hanging from a hook in front of him. The piranhas ate it, but Dr. Axelrod, the gigantic meat bag, stood utterly alone.

Though piranhas have a reputation for being ravenous carnivores who go absolutely bonkers at the smell of blood, the truth is that they are rather timid omnivores. Piranha, even the most carnivorous varieties, behave almost like freshwater vultures: they prey on the lifeless and dying rather than the life, which may bite back. (And if you’re still interested, check out: Doesn’t Consumption of Dead Things Make Vultures Sick?) One notable exception is that these creatures will consume extremely tiny fish, worms, and similar foods, which do not pose much of a danger to themselves.

Piranhas travel in large groups, which reduces the amount of food available to individual piranhas when they encounter prey. The reason they team up in shoals is actually to protect themselves from predators, not to overpower and devour large prey as popular culture would have you believe. Birds, dolphins, caimans, bigger fish, and people all consume piranhas, which are at the very bottom of the food chain. However, as Teddy Roosevelt pointed out, piranhas are also quite bony.

When left alone in a tank, piranhas exhibited behavior similar to uneasiness or dread, according to a 2005 study; researchers had to cover the fish’s tanks with cloth to prevent them from becoming overly anxious. Piranhas, when kept as pets, often hide when people are near their tank. This behavior can even persist when feeding them, and they will only come out when there is no one else nearby. While piranhas still typically swim away! when confronted with big predators, they are considerably less timid while swimming in schools.

While studies on piranha behavior aren’t as extensive as we’d like, most people think that the fish’s bad record is mostly undeserved. As the scientist Dr. Anne E. Magurran humorously put it, “Basically like regular fish.” Having big fangs. (Tupi means teeth fish, which is where their name comes from.)

Facts About Piranhas

• While infamous for carnivorous tendencies, piranhas are omnivores and consume various foods including fish, insects, plants, and even fruits that fall into the water.
• Piranhas are opportunistic feeders. Their feeding frenzies often occur due to heightened competition for limited resources, not just the presence of blood or flesh.
• Certain piranha species display impressive parenting behavior. They guard their nests fiercely and may even carry their eggs and young in their mouths to protect them from predators.
• Some species of piranhas have adapted to different habitats, such as living in flooded forests during the rainy season and returning to rivers during drier periods.
• Piranhas establish dominance hierarchies within their shoals. There’s a clear structure where larger and more aggressive individuals typically lead the group.
• Breeding behavior among piranhas varies widely. Some species lay eggs on aquatic plants, while others deposit their eggs in pits dug into riverbanks.
• Interbreeding between different piranha species can occur, leading to hybrids with unique physical and behavioral traits.
• Certain piranha species exhibit seasonal migrations in search of food or more suitable breeding grounds, showcasing their adaptability.
• They communicate through various signals, including visual cues, body postures, and even vocalizations, to establish dominance and maintain social order.
• Piranhas can be skittish around humans and typically avoid interaction. Most attacks on humans occur due to disturbance or feeding, and fatalities are exceedingly rare.

Separating Fact from Fiction

Infamous Reputation vs. Real Danger

Piranhas have gained notoriety for their terrifying reputation as flesh-stripping predators. Contrary to myths, most attacks on humans lead to minor injuries, primarily to the extremities. While fatalities are exceedingly rare, a few recent incidents in Paraguay in 2022 saw four individuals succumbing to piranha attacks.

Devouring a Human Body: Myth or Reality?

Rumors about piranhas devouring a human body to the bone in a matter of minutes abound. However, the reality contradicts this sensationalism. Starving a shoal of 300 to 500 piranhas might lead them to attack an adult human, yet such an occurrence is exceptionally rare and would take several minutes, not seconds.

The biting power of piranhas is notable, and their sharp teeth can slice through bone. However, attacks are primarily limited to nipping at extremities, rarely inflicting severe harm or fatality. Despite their menacing appearance, these fish exhibit timid behavior when kept in captivity, often shying away from human interaction.

Historical Records and Modern Existence

Piranhas continue to thrive in the freshwater bodies of South America, ranging from Venezuela’s Orinoco River Basin to Argentina’s Paraná River. While historical records have highlighted incidents, the contemporary existence of piranhas poses minimal risk to humans, with attacks generally limited and rarely life-threatening.

Paranha Statistics

• Historical records document instances where fatal piranha attacks occurred, albeit infrequently. A few reported cases mention fatalities caused by piranha attacks in regions of South America, predominantly near river basins. Although rare, these incidents indicate the potential threat piranhas pose under certain circumstances.
• Records also cite incidents of non-lethal attacks resulting in injuries. These injuries typically involve bites to extremities, causing varying degrees of harm. While most piranha attacks lead to minor wounds, some severe cases have been reported.
• Piranha attacks, whether causing fatalities or injuries, have often been concentrated in specific regions of South America, including river systems and lakes within the continent. These attacks are primarily observed in areas where piranhas are native and abundant.
• Studies have indicated that piranha behavior during attacks can vary based on factors such as the availability of food, water conditions, and the presence of other competing species. The frequency and severity of attacks may fluctuate based on these environmental factors.
• Recent data on piranha attacks might indicate evolving patterns or changes in their behavior. Monitoring and recording incidents helps track any shifts in piranha behavior, potential threats to human safety, and the effectiveness of conservation measures implemented in these regions.

After all that, the piranha is perfect for ripping and tearing flesh because of their sleek, muscular bodies, which allow them to bursts of speed that are unbelievably fast, their teeth that are sharp like knives, and their bite, which is among the strongest of any bony fish (and, compared to their size, among the strongest of any vertebrate in the world). Regarding the red-bellied piranha in particular, its bite is so powerful that it may snap a man’s finger bones like a “pair of bolt cutters” or swiftly take a more delicate section of his body.