Nocturnal South American monkey. Its eyes are very large and its thick coat is a grey brown. Douroucoulis sleep in tree holes or thick vegetation and feed mainly on fruit and leaves, and some insects. They are the only nocturnal monkeys.

Unlike most South American monkeys, their long tails are not prehensile. The incisors in the lower jaw project forwards and they have a total of 36 teeth.

Classification
Douroucoulis are in the genus Aotus in the family Cebidae, order Primates.