The orangutans are the two exclusively Asian species of extant great apes. Native to Indonesia and Malaysia, orangutans are currently found in only the rainforests of Borneo and Sumatra. Classified in the genus Pongo, orangutans were considered to be one species. However, since 1996, they have been divided into two species: the Bornean orangutan (P. pygmaeus) and the Sumatran orangutan (P. abelii). In addition, the Bornean species is divided into three subspecies. The orangutans are also the only surviving species of the subfamily Ponginae, which also included several other species, such as the three extinct species of the genus Gigantopithecus, including the largest known primate Gigantopithecus blacki. Both extant species had their genomes sequenced and they appear to have diverged around 400,000 years ago. Orangutans diverged from the rest of the great apes 15.7 to 19.3 million years ago.
Classification
Orangutan Taxonomy
| Domain: | Eukarya |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Primates |
| Family: | Hominidae |
| Genus: | Pongo |
| Species: | P. albelii or P. pygmaeus |
Orangutans are classified in the domain Eukarya because their cells contain a nucleus and membrane bound organelles, and they are multicellular organisms. In contrast, Prokaryotes are unicellular organisms (such as bacteria) that do not contain a cell nucleus or membrane bound organelles.
They belong to the kingdom Animalia because Orangutans are Heterotrophs that ingest food into an internal cavity. Organisms belonging to the kingdom Animalia also lack cell walls and are motile at some stage during their life cycle.
The phylum Chordata includes animals that possess a Notochord at some stage during their development. Other distinguishing characteristics are the presence of a tail and pharyngeal gill slits at some stage in development, a complete digestive system, bilateral symmetry, and a well developed Coelom.
Orangutans are contained in the class Mammalia because they are warm-blooded, possess hair on their body, have a four-chambered heart, and females produce milk from their mammary glands to nourish their young.
The order Primates has defining characteristics that are present in Orangutans such as the presence of differentiated tibia & fibula in the shank and ulna & radius in the forearm, presence of a clavicle, and possess five digit feet.
The family Hominidae exhibit both an opposable thumb and big toe (except humans), elimination of a tail, a large braincase, and flattened nails at the ends of the phalanges.
Orangutans are separated into the genus Pongo because they share less characteristics with humans than do Gorillas and Chimpanzees.
Habitat
Orangutans are found in Indonesia on the islands of Sumatra and Borneo. These apes were once widespread throughout mainland Asia during the Pleistocene . Orangutans prefer a habitat that exists along waterways and in lowlands because of their high dependence on fruit. Biologists have described their habitats as inaccessible, swamp logged, leech-laden tropical forests. The islands of Borneo and Sumatra have vast mountain ranges and Orangutans are rarely seen in elevations that exceed 500 meters. An Orangutan's normal habitat is the tropical rainforest that is dominated by trees of the family Dipterocarpaceae, which interestingly enough, is also becoming endangered in parts of the world.
In Sumatra, Orangutans are entirely arboreal because of large predators (such as tigers, leopards) patrol the forest floor. Borneo contains fewer large predators so males will travel Terrestrially and feed on the ground, but females will remain in the trees because of their smaller size. In traveling through trees, Orangutans have shown intelligence by using common routes and showing the ability to back track to their original route if need be. Orangutans are slow and deliberate animals and their movement in the trees reflects this. It has also been seen that Orangutans can occupy peat swamp forest in addition to tropical forest. Their habitat mainly reflects areas where the greatest majority of food is located and areas that will give them the most protection.
Map of Orangutan Distribution in Sumatra & Borneo
Body plan
Orangutans are the most arboreal of the great apes and spend most of their time in trees. Their hair is typically reddish-brown, instead of the brown or black hair typical of chimpanzees and gorillas. Males and females differ in size and appearance. Dominant adult males have distinctive cheek pads and produce long calls that attract females and intimidate rivals. Younger males do not have these characteristics and resemble adult females. Orangutans are the most solitary of the great apes, with social bonds occurring primarily between mothers and their dependent offspring, who stay together for the first two years. Fruit is the most important component of an orangutan's diet; however, the apes will also eat vegetation, bark, honey, insects and even bird eggs. They can live over 30 years in both the wild and captivity.
role in ecosystem
The orangutan plays a very important role in the lowland rainforests of Sumatra and Borneo and is considered a keystone species. Keystone species are species whose very existence in an ecosystem greatly effects the health of other species and the ecosystem at large. When a keystone species' numbers decline or they completely disappear, the survival and abundance of many other species in the ecosystem are negatively impacted. A comparison of different rainforest areas in Sumatra and Borneo where orangutans live shows that the biodiversity of plant and animal species is also the highest. As fruit eaters and travelers, orangutans play a large part in dispersing seeds and keeping diversity of rainforest woody plants. Their protection is vital to the overall health of the lowland forest ecosystem in which they thrive. In contrast, the vitality of the orangutan population will only flourish if their forest home is kept undisturbed and intact.
