Elephants' ears have many roles. First, elephants have an excellent hearing that allows them to hear infrasound and to communicate over long distances. They are also use to express moods. Finally, they have a key role in thermoregulation. Very thin, they have a very dense network of blood capillaries, where all the blood is going through in about 20 minutes. By flapping the ears, covering them with water or mud, the elephant ensures thermal exchanges and keeps an adapted body temperature.