There are many different groups of animals. Of those animals that are mammals, one family is the primates, the group that consists of monkeys, apes and humans.  Gorillas are the largest of the apes and are closely related to humans. They are highly intelligent animals that communicate with each other through a wide range of sounds, body postures and gestures.

Habitat and Distribution (where they are found)

Gorillas are found only in Africa. They are forest dwellers, living in tropical rainforests, forests alongside rivers,  swamps and forest edges.  There are two species, or kinds, of gorilla: the eastern gorilla and the western gorilla.  As the names suggest, this is because of the areas in Africa where they live.

Young mountain gorilla riding on mum's back. ©Getty Images

Young mountain gorilla riding on mum's back. ©Getty Images

There are two groups of eastern gorillas: the eastern lowland gorilla (the largest of the gorillas) and the mountain gorilla.

There are two groups of western gorillas: the Cross River gorilla and the western lowland gorilla.

There are only small differences between them, mostly some size, colouring and fur length. For example, mountain gorillas live at altitudes of 2500 to 5000 metres where temperatures can drop below freezing point, so they have longer, thicker fur than any other of the great apes.

Appearance and Behaviours

Lowland silverback male. ©Getty Images

Lowland silverback male. ©Getty Images

A gorilla's body is covered with black or brown hair.  There is no hair on the face, chest, on the palms of the hands, or on the soles of the feet.

Gorillas move by walking on all fours, but can walk on two. When walking on all fours, their back feet are flat on the ground and their arms rest on their knuckles to support their heavy upper body.  Males can be about 1.7 metres tall when standing on two legs, and females about 1.5 metres. Males can weigh up to 240 kg, females up to 100kg.

Physical characteristics of gorillas include:

Gorillas have domed head and high forehead. ©Getty Images

Gorillas have domed head and high forehead. ©Getty Images

  • individual nose shapes, different in each gorilla;
  • the forehead bulges and the head is a high dome;
  • small ears that lie close to the head;
  • no tail;
  • large intestines, necessary in order to digest plants;
  • broad chest (can measure 1 metre across in a large male);
  • arms that are longer and more strongly muscled than the legs;
  • outstretched arms can measure over 2 mfingertip to fingertip;
  • four fingers on each hand, with an opposable thumb (like a human's, the thumb can be moved across the palm);
  • five toes on each foot, with an opposable big toe;
  • individual thumb and toe prints.
Eastern lowland silverback male ©Getty Images

Eastern lowland silverback male ©Getty Images

Silverbacks

When male gorillas are about 10 years old, the hair on the lower to middle part of their backs turns silver-grey, and then they are known as silverbacks. Gorillas live in groups of up to 30, called a troop.  In the troop there are adult males, adult females and several young gorillas. One adult male silverback leads the group. He decides when it is time for the group to get up in the morning, where to wander in the forest, and when it is time to rest.

Mountain gorilla silverback ©Getty Images

Mountain gorilla silverback ©Getty Images

The silverback also protects the group from danger. A new troop forms when one or more females join another adult male.  Each troop has its own home territory, an area from 5 to 39 square kilometres. Troops of gorillas may live in the same area of a forest but the troops usually keep out of each other's way.

Gorillas look fierce, but they are actually shy, friendly animals. A gorilla will not hurt a human unless it is attacked or it feels afraid. When a gorilla wants to frighten an enemy it stands up on its legs and slaps its hands against its chest to make a loud noise to scare away the enemy. The male gorilla roars too.  Gorillas usually stay on the ground, but sometimes they climb into trees to sleep or eat.

Diet

Gorillas eat leaves, buds, bark, and fruits. A large male gorilla may eat as much as 27 kilograms of food each day. They eat in the morning, and in the afternoon they rest and sleep. Then, in the late afternoon or just before dark they eat again.   At night time gorillas build nests with branches and leaves on the ground or in trees.  Each gorilla builds its own nest. Baby gorillas sleep with their mothers. Gorillas never spend more than one night in the same place.

A mountain gorilla with her newborn. ©Getty Images

A mountain gorilla with her newborn. ©Getty Images

Life Cycle

A baby gorilla stays close to its mother ©Getty Images

A baby gorilla stays close to its mother ©Getty Images

Female gorillas can mate when they are about 8 years old, and males when they are 12 years old.  About 9 months after mating with a male, the female gives birth, usually to a single young, twins are rare.  A newborn gorilla weighs about 2 kg. At first the female carries her baby in her arms. The baby sucks milk from its mother's nipples.  

After about three months, and for its early years a young gorilla rides on its mother's back, holding onto her fur. By the age of 3 months the baby can crawl, and by 5 months it can walk. The young gorilla stays close to its mother for about three and a half years.

Conservation Status and Threats

Eastern lowland gorillas are classified as Endangered (with about 3000 left in the wild);
the western lowland, mountain and Cross River gorillas are now classified as Critically Endangered.

The main threats to gorillas are habitat loss and hunting. People hunt gorillas for food and cut down the forests where they live. The gorilla has become rare in many parts of Africa. Gorillas also suffer from many diseases spread by mosquitoes and ticks, and also humans. A number of conservation plans have been put in place to save gorillas.

Read more about gorillas and conservation.

http://www.worldwildlife.org/species/mountain-gorilla

Watch video

http://video.nationalgeographic.com/video/exploreorg/gorilla-talk-eorg