For centuries, travellers to South America have brought back some gruesome stories about fish with teeth that can strip the flesh of any animal foolish enough to try to cross the rivers that are their home. These stories were about piranhas, freshwater fish with razor-sharp teeth. In fact, the term piranha in a Brazilian language means ‘tooth fish’.
Most of the piranhas are sized between 12 and 35 centimeters. The red-bellied piranha is the largest among the lot and it grows to a size of half a meter!
Piranhas hunt in groups of more than a hundred members. Several groups can converge in a feeding frenzy if a large animal is attacked, although this is rare. Piranhas have excellent hearing capability. When a piranha locates the prey, signals are sent to the group acoustically. Everyone in the group rushes in to take a bite and then swims away to make way for the others.