Notes

Gorillas are the largest apes. They are also the largest animals of the group called primates, which also includes the other apes, humans, and monkeys. After chimpanzees and bonobos, gorillas are the closest living relatives to humans. Movies often show gorillas as fierce creatures. But they are actually peaceful and gentle animals.

Gorillas live in rainforests in Africa. There are four kinds of gorilla. The two western gorillas are the western lowland gorilla and the Cross River gorilla. Both are found in western Africa. The two eastern gorillas are the eastern lowland, or Grader' Hair and Skin:
Gorillas are covered with brownish hair on most of their body (except their fingers, palms, face, armpits, and bottoms of their feet).
The Head:
Gorillas have a very large head with a bulging forehead, a crest on top (it is called the sagittal crest, and is larger on male gorillas), tiny ears, and small, dark-brown eyes. Gorillas have no tail. Adult gorillas have 32 teeth, with large molars (flat teeth used for chewing food) and large canines (pointy teeth used for biting), which are especially large in the male gorillas. Gorillas each have a unique nose print (like we have unique fingerprints).
Senses:
Gorillas have senses very similar to ours, including hearing, sight (they seem to be slightly nearsighted and to have color vision), smell, taste, and touch.
Hands and Feet:
Gorillas' hands are very much like ours; they have five fingers, including an opposable thumb. Their feet have five toes, including an opposable big toe. Gorillas can grasp things with both their hands and their feet.
SIZE
Male gorillas are much larger than the females, and are almost twice as heavy. Adult male gorillas are called silverbacks because they have a saddle-shaped patch of silver hair on their backs after they are about 12 years of age.

Gorillas
Height
Weight
Female
4.6 ft (1.4 m)
200 lb (90 kg)
Male
5.6 ft (1.7 m)
400 lb (180 kg)

DIET
Gorillas are predominantly herbivores, eating mostly plant material. They forage for food in the forests during the day. They eat leaves, fruit, seeds, tree bark, plant bulbs, tender plant shoots, and flowers. They have been known to eat various parts of over 200 different plant species. Occasionally, gorillas supplement their diet with termites and ants.
Gorillas rarely drink water; the water contained in their diet is apparently enough to sustain them.
An average adult male eats approximately 50 pounds of food a day.

INTELLIGENCE AND LANGUAGE
Gorillas are very intelligent and can learn extremely complex tasks.
Language:
Some gorillas have been taught sign language by people; these gorillas learned how to form simple sentences and communicate with people.
Tools:
Gorillas have never been observed using tools in the wild, although they have been taught to use them in captivity.

BEHAVIOR AND SOCIAL HABITS
Bands of Gorillas:
Gorillas are shy, social animals that are active during the day (they are diurnal). They live in small groups (or bands) of 6-7 individuals, including one silverback (adult male), a few females, and their young. When the young mature, they go off and join or form another band.
Grooming:
Grooming one another (cleaning the hair of another gorilla) is a major occupation among gorillas in a band. Female gorillas groom their offspring, one another, and the silverback; the silverback does not groom others.
Sleeping Nests:
Each evening, gorillas construct a "nest" for the night in which they will curl up and sleep. These bowl-shaped nests are made out of leaves and other plant material. Nests are only shared by a mother and her nursing offspring. Scientists who study gorillas can easily estimate a local gorilla population by counting the number of "nests."
Aggression:
Gorillas are not aggressive animals. When an intruder disturbs them, they may make a lot of noise, but they rarely confront another animal.
COMMUNICATION AND VOCALIZATION
Gorillas are generally quiet animals. They communicate with each other using many complicated sounds and gestures. Gorillas use at least 25 recognized vocalizations, including grunts, roars, growls, whines, chuckles, hooting, etc. Some gorilla gestures include chest-beating, high-pitched barks, lunging, throwing objects, staring, lip-tucking , sticking out the tongue, sideways running, slapping, rising to a two-legged stance, etc.

Communication is used to teach the young the many skills that they need to survive, and for other gorillas to communicate about food, social relationships, distress, mating, etc.
LOCOMOTION
Gorillas knuckle-walk using both their legs and their long arms (putting pressure on their knuckles, with the fingers rolled into the hand). Gorillas rarely walk using only their legs. They can climb trees, but do not do so very often. Gorillas cannot swim.
LIFE SPAN
Gorillas live about 50 years in captivity; their life span in the wild is only about 35 years (like most animals, they live much longer in captivity).
HABITAT
Gorillas are primarily terrestrial (although they lived in trees back in their evolutionary past). Gorillas live in tropical rain forests (in the forest edges and clearings), wet lowland forests, swamps, and abandoned fields. , gorilla and the mountain gorilla. Both are found in east-central Africa. All gorillas are endangered, or at risk of dying out. The mountain gorilla has become especially rare.

Adult male gorillas may be 5.5 feet (1.7 meters) tall and weigh 300 to 600 pounds (140 to 270 kilograms). The females weigh about half as much as the males. Adult gorillas have long, strong arms and short, stocky legs. The chest is very thick and strong. The males have a bony crest on top of the head. Gorillas have a coat of black hair except on their faces, hands, and feet.

Gorillas live in family groups of about 6 to 30 animals. One or two older males lead the group. Gorillas use their arms and legs to walk. They support part of their weight on the knuckles of the hands. They rarely stand up straight. Gorillas spend most of their time on the ground. But they may also climb trees to sleep and feed. Gorillas eat plants, including fruits, leaves, stalks, and shoots.