The orangutans are two endangered species of great apes. Known for their intelligence, they live in trees and are the largest living arboreal animal. They have longer arms than other great apes, and their hair is typically reddish-brown, instead of the brown or black hair typical of other great apes. Native to Indonesia and Malaysia, they are currently found only in rainforests on the islands of Borneo and Sumatra, though fossils have been found in Java, the Thai-Malay Peninsula, Vietnam and China. There are only two surviving species in the genus Pongo: the Bornean Pongo pygmaeus and the critically endangered Sumatran Pongo abelii. The subfamily Ponginae includes the extinct genera Gigantopithecus and Sivapithecus.
An orangutan's standing height averages from 4 to 5 feet (1.2 to 1.5m) and weighs between 73 to 180 lbs (33 to 82 kg). Males can weigh up to 250 lbs (113 kg) or more. 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 (2.3 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,. 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 to other females. The age of maturity for females is approximately 12 years. Orangutans may live for about 50 years in the wild. However, thousands of orangutans don't reach adulthood due to human disruption. Orangutans are killed for food while others are killed because of disruption in people's property. Mother orangutans are killed so their infants can be sold as pets. Many of the infants die without the help of their mother.  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 centimetres and weigh around 100 lbs or 45 kg, while flanged adult males can reach 5 ft 9 in or 175 centimetres in height and weigh over 260 lbs or 118 kg. 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.
Fruit makes up 65%-90% of the orangutan diet. Fruits with sugary or fatty pulp are favored. Ficus fruits are commonly eaten, because they are easy to harvest and digest. Lowland Dipterocarp forests are preferred by orangutans because of their plentiful fruit; the same forests provide excellent timber for the logging industry and good soil conditions for palm oil plantations. Bornean orangutans consume at least 317 different food items that include: young leaves, shoots, seeds, bark, insects, honey, and bird eggs. Orangutans are opportunistic foragers, and their diets vary markedly from month to month. Bark is consumed as a last resort in times of food scarcity; fruits are always preferred. Orangutans are thought to be the sole fruit disperser for some plant species including the climber species Strychnos ignatii which contains the toxic alkaloid strychnine. It does not appear to have any effect on orangutans except for excessive saliva production. Geophagy, the practice of eating soil or rock, has been observed in orangutans. There are three main reasons for this dietary behavior; for the addition of minerals nutrients to their diet; for the ingestion of clay minerals that can absorb toxic substances; or to treat a disorder such as diarrhea. Orangutans use plants of the genus Commelina as an anti-inflammatory balm..