One adaptation piranhas exhibit is that they swim in schools, especially when they are still young. It is a defense mechanism against their natural predators. Despite their ferocity, many animals prey on piranhas, including birds, water snakes, sharks, adult piranhas and humans.
Piranhas are carnivorous animals, and their teeth and jaw structures are highly adapted to cutting and tearing the flesh of their prey. Their powerful jaws and small, triangular, razor-sharp teeth are arranged similarly to shark teeth, allowing them to puncture and shear their prey's flesh rapidly. Piranhas have thick scales on their heads, which serve as a buffer when their heads bump against the carcasses on which they are feeding.