Defence against predators
Warning sounds: Sometimes the same principle occurs with senses other than sight. Warning sounds allow the animal to stay hidden. Rattlesnakes are a good example: they need crypsis to avoid alerting their prey, and use the rattle to avoid being accidentally injured by large animals. Moths of the Arctiidae and Ctenuchidae families are foul-tasting, but might be eaten by bats at night. These moths emit clicks when they hear bats in flight. That the clicks work is shown by a neat experiment. Bats eat mealworms if thrown up by the experimenter. They ignore the mealworms thrown by hand if moth clicks are played at the same time.