Piranha, << pih RAHN uh or pih RAHN yuh, >> is a sharp-toothed fish. It lives in lakes and rivers throughout most of lowland tropical South America. Piranhas have a reputation as vicious, swarming fish that can tear a person to shreds in seconds. In truth, piranhas rarely attack people. However, piranhas can be a serious problem if introduced into new waters. There, they may eat large numbers of native fish, amphibians, and other animals.
There are dozens of species (kinds) of piranhas. All have tall, narrow bodies. They range in color from olive-green to blue-black. Many piranhas have characteristic red or orange bellies. The red-bellied piranha, a common species, can reach 1 foot (30 centimeters) long.
The piranha has short, powerful jaws and sharp teeth. It uses them to puncture and shear away flesh. The razor-sharp teeth are arranged in a single row on each jaw. These teeth are tightly packed and interlocking. Each tooth resembles a triangular, pointed blade.
During the wet season, the piranha swims alone and feeds on smaller fish, insects, worms, and other animals. It may also pick seeds and fruits from the branches of flooded trees. During the dry season, when the water is low, piranhas may become packed into small pools. In these pools, piranhas will attack almost anything edible. They may even bite away pieces of flesh from large animals that have become injured, such as cattle.
The piranha is an important predator (hunting animal) in its natural environment. Despite its reputation, it is not a vicious pack hunter. Like most fish, piranhas form schools for protection from predators, including larger fish, birds, and river dolphins.
