The orangutans are a species of great apes. Known for their intelligence, they live in trees and they are the largest living arboreal animal. They have longer arms than other great apes, and their hair is 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. They are the only surviving species in the genus Pongo and the subfamily Ponginae (which also includes the extinct genera Gigantopithecus and Sivapithecus).
Etymology
The word orangutan (also written orang-utan, orang utan and orangutang) is derived from the Malay and Indonesian words orang meaning "person" and hutan meaning "forest",[2] thus "person of the forest". Orang Hutan is the common term in these two national languages, although local peoples may also refer to them by local languages. Maias and mawas are also used in Malay, but it is unclear if those words refer only to orangutans, or to all apes in general.
The word was first attested in English in 1691 in the form orang-outang, and variants with -ng instead of -n as in the Malay original are found in many languages. This spelling (and pronunciation) has remained in use in English up to the present, but has come to be regarded as incorrect.[3]
The name of the genus, Pongo, comes from a 16th century account by Andrew Battell, an English sailor held prisoner by the Portuguese in Angola, which describes two anthropoid "monsters" named Pongo and Engeco. It is now believed that he was describing gorillas, but in the late 18th century it was believed that all great apes were orangutans; hence Lacépède's use of Pongo for the genus.[4]
Ecology and appearance
Orangutans are the most arboreal of the great apes, spending nearly all of their time in the trees. Every night they fashion nests, in which they sleep, from branches and foliage. They are more solitary than the other apes, with males and females generally coming together only to mate. Mothers stay with their babies until the offspring reach an age of six or seven years. There is significant sexual dimorphism between females and males: 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.[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 walk on the ground by shuffling on their palms with their fingers curved inwards.[6]
Diet
Fruit makes up 65% of the orangutan diet. Fruits with sugary or fatty pulp are favored. Lowland Dipterocarp forests are preferred by orangutans because of their high fruit abundance, the same forests that provide excellent timber for the logging industry and good soil conditions for palm oil plantations. The fruit of fig trees are also commonly eaten since it is easy to both harvest and digest. Bornean orangutans are recorded to consume at least 317 different food items and include: young leaves, shoots, seeds and bark. Insects, honey and bird eggs are also included.[7][8]
Orangutans are highly opportunistic foragers with the composition of their diet varying markedly from month to month.[9] Bark as a source of nourishment is only consumed as a last resort in times of food scarcity, fruits always being the preferred choice. 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.[10] 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.[11] Orangutans use plants of the genus Commelina as an anti-inflammatory balm.[12]
Diet
Fruit makes up 65% of the orangutan diet. Fruits with sugary or fatty pulp are favored. Lowland Dipterocarp forests are preferred by orangutans because of their high fruit abundance, the same forests that provide excellent timber for the logging industry and good soil conditions for palm oil plantations. The fruit of fig trees are also commonly eaten since it is easy to both harvest and digest. Bornean orangutans are recorded to consume at least 317 different food items and include: young leaves, shoots, seeds and bark. Insects, honey and bird eggs are also included.[7][8]
Orangutans are highly opportunistic foragers with the composition of their diet varying markedly from month to month.[9] Bark as a source of nourishment is only consumed as a last resort in times of food scarcity, fruits always being the preferred choice. 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.[10] 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.[11] Orangutans use plants of the genus Commelina as an anti-inflammatory balm.[12]
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