Orangutans are primates, and a member of the great ape family of animals that includes gorillas, chimpanzees, bonobos and humans. Identifiable by their long orange/ reddish hair, large body size and long arms, the two species of orangutan, the Sumatran orangutan (Pongo abelii) and the Bornean orangutan (Pongo pygmaeus) are the largest arboreal, or tree-dwelling, animals in the world.