For years the world's largest primate has been portrayed as a fearsome and aggressive beast. But gorillas are actually gentle giants, who have strong family ties and feed on nothing more sinister than vegetation.

Subspecies
Two subspecies: G. g. gorilla (western lowland), G. g. diehli (cross river).

Life span
50 years.

Statistics
Males measure 170-180cm and weigh 140-275kg. Females measure 140-150cm and weigh 60-100kg.

Physical description
The western gorilla has an overhanging tip on its nose, which differentiates it from the eastern gorilla. Gorillas in general have short legs, long muscular arms, a wide chest, a large head and large canine teeth. The hands are broad with short digits.

Distribution
Western lowland gorillas live in forested areas of Cameroon, Central African Republic, Equatorial Guinea, People's Republic of Congo, Angola and Gabon. Cross river gorillas inhabit Nigeria and Cameroon.

Habitat
Western gorillas live within the tropical rainforest.

Diet
Gorillas mainly feed on leaves, but they also consume fruit, seeds, flowers, roots, herbs, insects and clay. The western lowland eats more fruit than its counterpart, the mountain gorilla.

Behaviour
Gorillas form relatively stable, mixed-sex groups. Solitary animals, (usually fully adult males), make up approximately 10 per cent of the population. They are diurnal and mainly terrestrial. Gorillas tend to move across the forest floor on their knuckles, and they are capable of moving bipedally. They make a new sleeping nest every night.

Each gorilla group is led by the dominant male, the "silverback". All the members of the group are either his mates or his offspring. He decides when the group wakes, eats and when it moves location in search of food.

Each gorilla group needs about 10km2 of forest to get enough food to survive, but gorillas are not territorial and they may share their often overlap their ranges with other gorillas.

When male gorillas reach maturity at between 9-12 years of age, they leave the group to start their own.

Reproduction
Gorillas give birth to one young (very rarely, twins) after a gestation period of 251-289 days. The young weigh 2kg at birth.

Conservation status
Western gorillas are listed as Endangered by the 2000 IUCN Red List. The entire population of gorillas is seriously threatened due to the destruction of their habitat and by trophy/meat hunting. Overall there are probably fewer than 100,000 gorillas, including about 94,500 western lowland gorillas and 150-200 cross river gorillas.