Piranhas are well known for their razor sharp teeth, and have a reputation for having voracious appetites. Although they are known to occasionally attack large animals, the reputation is greatly exaggerated. Most adult piranhas - depending on the species - eat fruit, seeds, and fish. Some have been found with bird fragments, snakes, and small mammals in their stomachs. Young piranhas may eat cope pods, crustaceans, and insects. Piranhas may feed more aggressively when their normal food resources become scarce. Water levels of their river homes fall during the dry season. Piranhas may become trapped in stagnant pools for weeks. When all of the food in these pools is consumed, piranhas may eat anything that enters the water.