orangutan

An orangutan's standing height averages from 4 to 5 ft (1.2 to 1.5 m) and weighs between 73 to 180 pounds (33 to 82 kg).[2] Males can weigh up to 250 lb (110 kg) or more.[3] Orangutan hands are similar to humans hands; they have four long fingers and an opposable thumb. Their feet have four long toes and an opposable big toe. Orangutans can grasp things with both their hands and their feet. The largest males have an arm span of about 7.5 ft (2 m).

Orangutans have a large, bulky body, a thick neck, very long, strong arms, short, bowed legs, and no tail. They are mostly covered with long reddish-brown hair, although this differs between the species: Sumatran Orangutans have a more sparse and lighter coloured coat.[4]

The orangutan has a large head with a prominent mouth area. Adult males have large cheek flaps (which get larger as the ape ages) that show their dominance to other males and their readiness to mate. The age of maturity for females is approximately 12 years. Orangutans may live for up to 50 years in the wild.

Orangutans are the most arboreal of the great apes, spending nearly all of their time in the trees. Every night they fashion sleeping nests from branches and foliage. They are more solitary than other apes; males and females generally come together only to mate. Mothers stay with their babies for six or seven years. There is significant sexual dimorphism: females can grow to around 4 ft 2 in or 127 cm and weigh around 100 lb (45 kg) while flanged adult males can reach 5 ft 9 in or 175 cm in height and weigh over 260 lb (118 kg).[5]

The arms of orangutans are twice as long as their legs. Much of the arm's length has to do with the length of the radius and the ulna rather than the humerus. Their fingers and toes are curved, allowing them to better grip onto branches. Orangutans have less restriction in the movements of their legs than humans and other primates, due to the lack of a hip joint ligament which keeps the femur held into the pelvis. Unlike gorillas and chimpanzees, orangutans are not true knuckle-walkers, and are instead fist-walkers.