The body is rotund and covered with long hair in various shades of red. Old males usually develop large cheek pads and facial hair that resembles a man's moustache and beard. Enormous throat pouches also develop with sexual maturation, which starts at about age 14. Males are aggressive toward each other and fight over females. Individual nests are usually constructed in trees each night.
Fruit is a diet mainstay, and orangutans are important seed distributors.
Fewer than 30,000 individuals are believed to remain in the wild, and the species is listed as endangered. Orangutans are classified in the phylum Chordata , subphylum Vertebrata, class Mammalia, order Primates, family Pongidae. The Columbia Encyclopedia, Sixth Edition.