Gorilla, Wild animals

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Gorillas are the largest of the living primates. They are ground-dwelling and predominantly herbivorous. They inhabit the forests of central Africa. Gorillas are divided into two species and (still under debate as of 2008) either four or five subspecies. The DNA of gorillas is 98%–99% identical to that of a human,[2] and they are the next closest living relatives to humans after the two chimpanzee species.

Gorillas live in tropical or subtropical forests. Although their range covers a small percentage of Africa, gorillas cover a wide range of elevations. The Mountain Gorilla inhabits the Albertine Rift montane cloud forests of the Virunga Volcanoes, ranging in altitude from 2,200–4,300 metres (7,200–14,100 ft). Lowland Gorillas live in dense forests and lowland swamps and marshes as low as sea level.

Evolution and classification

Female gorilla.

The closest relatives of gorillas are chimpanzees and humans, from which gorillas diverged about 7 million years ago.[5] Human genes differ only 1.6% on average from their corresponding gorilla genes in their sequence, but there is further difference in how many copies each gene has.[6]

Until recently there was considered to be a single gorilla species, with three subspecies: the Western Lowland Gorilla, the Eastern Lowland Gorilla and the Mountain Gorilla.[7][8] There is now agreement that there are two species with two subspecies each. More recently it has been claimed that a third subspecies exists in one of the species.

Primatologists continue to explore the relationships between various gorilla populations.[7] The species and subspecies listed here are the ones upon which most scientists agree.[citation needed]
Genus Gorilla   
Western Gorilla (Gorilla gorilla)
Western Lowland Gorilla (Gorilla gorilla gorilla)
Cross River Gorilla (Gorilla gorilla diehli)
Eastern Gorilla (Gorilla beringei)
Mountain Gorilla (Gorilla beringei beringei)
Eastern Lowland Gorilla (Gorilla beringei graueri)

The proposed third subspecies of Gorilla beringei, which has not yet received a trinomen, is the Bwindi population of the Mountain Gorilla, sometimes called the Bwindi Gorilla.
Physical characteristics


Two Western Lowland Gorillas move around at Ueno Zoo.

Gorillas move around by knuckle-walking. Adult males range in height from 1.65–1.75 metres (5 ft 5 in–5 ft 9 in), and in weight from 140–200 kg (310–440 lb). Adult females are often half the size of a silverback, averaging about 1.4 metres (4 ft 7 in) tall and 100 kg (220 lb). Occasionally, a silverback of over 1.8 metres (5 ft 11 in) and 230 kg (510 lb) has been recorded in the wild. However, obese gorillas in captivity have reached a weight of 270 kg (600 lb).[9] Gorillas have a facial structure which is described as mandibular prognathism, that is, their mandible protrudes farther out than the maxilla.

The Eastern Gorilla is more darkly colored than the Western Gorilla, with the Mountain Gorilla being the darkest of all. The Mountain Gorilla also has the thickest hair. The Western Lowland Gorilla can be brown or grayish with a reddish forehead. In addition, gorillas that live in lowland forests are more slender and agile than the more bulky Mountain Gorilla Almost all gorillas share the same blood type (B)  and, like humans, have individual finger prints.[12]
Behavior
Group life
"Blackback" redirects here. For other uses, see Blackback (disambiguation).
"Silverback" redirects here. For other uses, see Silverback (disambiguation).

A silverback is an adult male gorilla, typically more than 12 years of age and named for the distinctive patch of silver hair on his back. A silverback gorilla has large canine teeth that come with maturity. Blackbacks are sexually mature males of up to 11 years of age.

A silverback gorilla portrait.

Silverbacks are the strong, dominant troop leaders. Each typically leads a troop (group size ranges from 5 to 30) and is in the center of the troop's attention, making all the decisions, mediating conflicts, determining the movements of the group, leading the others to feeding sites and taking responsibility for the safety and well-being of the troop. Blackbacks may serve as backup protection.

Males will slowly begin to leave their original troop when they are about 11 years old, traveling alone or with a group of other males for 2–5 years before being able to attract females to form a new group and start breeding. While infant gorillas normally stay with their mother for 3–4 years, silverbacks will care for weaned young orphans, though never to the extent of carrying the little gorillas. If challenged by a younger or even by an outsider male, a silverback will scream, beat his chest, break branches, bare his teeth, then charge forward. Sometimes a younger male in the group can take over leadership from an old male. If the leader is killed by disease, accident, fighting or poachers, the group will split up, as the animals disperse to look for a new protective male. Occasionally, a group may be taken over in its entirety by another male. There is a strong risk that the new male will kill the infants of the dead silverback.
Food and foraging

Female and baby gorillas.

Gorillas are herbivores  eating fruits, leaves, and shoots. Further they are classified as foliovores. Much like other animals that feed on plants and shoots, they sometimes ingest small insects as well (however there has been video proof that gorillas do eat ants and termites much in the same way as chimpanzees.)   Gorillas spend most of the day eating. Their large sagittal crest and long canines allow them to crush hard plants like bamboo. Lowland gorillas feed mainly on fruit while Mountain gorillas feed mostly on herbs, stems and roots. 
Reproduction and lifespan

Gestation is 8½ months. There are typically 3 to 4 years between births. Infants stay with their mothers for 3–4 years. Females mature at 10–12 years (earlier in captivity); males at 11–13 years. Lifespan is between 30–50 years, although there have been exceptions. For example the Dallas Zoo's Jenny lived to the age of 55.[15][16][17] Recently, gorillas have been observed engaging in face-to-face sex, a trait that was once considered unique to humans and the Bonobo.