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This post courtesy BBC Earth and the Deadly 60 Team. For more wildlife news, find BBC Earth on Facebook and Posterous.

Legend has it that piranhas gather in predatory shoals and can strip human beings to the bone and eat them alive. The yellow-bellied piranha has a horrific appearance, with a mouth packed full of canines 4 millimeters long, which, like sharks, are constantly replaced when lost or worn down.

Piranhas can also detect a drop of blood in 200 liters of water and shoals can clean off meat from a carcass with alarming effectiveness. Steve went in search of this notorious killer fish when he travelled to the Amazon river. Getting in the water to lure them in with a piece of steak had some frightening results:

Scary! But could they eat a human alive? Probably not.

Piranhas are neither carnivorous nor aggressive man-eaters. According to research in the UK piranhas are thought to be mainly scavengers, feeding on fish, plants, and insects, sometimes stripping meat from mammal carcasses that have ended up in the river. They also appear to be quite fearful, gathering in large shoals not to hunt down prey but rather to defend themselves against predators.

We’re pretty sure that no one has ever been eaten alive by piranhas, even if a few attacks have been reported. In fact, if they have eaten any humans it’s more likely because they have eaten the remains of a corpse lying on the river bed.

The myth of the aggressive piranha might be traced back to Theodore Roosevelt, who visited Brazil in 1914 and saw a piranha shoal rapidly strip the flesh from a dead cow. However, the show had been set up to entertain tourists; the captive fish had been kept hungry for days so they would go into a feeding frenzy.

We’re not suggesting you bathe in piranha-infested water with wild abandon. But we do think it’s safe to say most piranhas are peace-loving vegetable eaters, unlikely to devour you alive.

For more stories from Steve and the Deadly 60 team, check out the Deadly Diaries.