Night monkeys, also known as owl monkeys or douroucoulis, are nocturnal New World monkeys of the genus Aotus, the only living member of the family Aotidae. The genus comprises eleven species which are found across Panama and much of South America in primary and secondary forests, tropical rainforests and cloud forests up to 2,400 metres (7,900 ft). Night monkeys have large eyes which improve their vision at night, while their ears are mostly hidden, giving them their name Aotus, meaning "earless".