Gorillas, the largest, strongest, rarest apes, look
the most human of all other primates. They
live in equatorial West African forests, from lowlands
near the Cameroon Coast to highland altitudes
of 10,000 feet in Rwanda, Zaire, and Uganda.
All gorillas are believed to belong to one species,
Gorilla gorilla.
Physical Characteristics of Gorillas
Males are 5.75 feet tall when on all fours, over six
feet when standing erect, and thus are taller than
the average man. They are much heavier, weighing
three hundred to six hundred pounds. Unsurprisingly,
their bone structure is heavier than that
of humans. Females, a foot shorter than males,
weigh half as much. Gorilla skin is dark and, except
for the face and hands, covered with long,
coarse, dark brown to black hair. This hair turns
gray on the backs of older males, who are then
called silverbacks.
Gorillas, especially males, look fierce, although
they are timid unless mating, cornered, or threatened.
Their fierce looks are due to hulking bodies
and somber faces, with dark, hairless, strong jaws
and long, powerful teeth. In addition, gorillas
have brutish brow ridges which jut out above
small eyes. Finally, the face of the male is dominated
by a large, flat nose with coarse nostrils.
Combined, these features produce what humans
perceive as a somber and threatening expression.
Gorilla brain cases and brain sizes are smaller
than in humans, promising lower intelligence. As
to skeletal structure, the gorilla is similar to humans,
but its bones are thicker. Its arms are much
longer and its legs are much shorter. Gorilla
spines lack the structures needed for a continual
erect posture. Therefore, while gorillas can stand
upright and walk erect, most often they walk on
all fours, using the knuckles of their hands as supports.
Life and Sexual Cycles of Gorillas
Contrary to their legendary savagery, reinforced
by their appearance, gorillas are shy, friendly creatures.
Once they become used to unthreatening intruders,
as Dian Fossey discovered, these individuals
are accepted. Initially, males of gorilla groups
charge intruders, growling and beating their
chests. Intruders who run are often killed. Those
who stand their ground and behave in an unthreatening
manner are not harmed.
Gorillas live in families and extended families
(bands) of five to twenty individuals.Aband has a
silverback leader, up to three subordinate males
who help protect it, several mature females, and
numerous young. The silverback drives most
young gorilla males away at maturity. At these
times all males are fierce and use their strength
to attain and maintain supremacy. Males driven
off form bachelor groups or join other bands.
Silverbacks, challenged and defeated, live alone.
Gorilla bands each have a territory they allow
others to enter. A band lacks permanent dwellings.
Rather, its members build temporary shelters
each night after a long day of travel to forage
for the honey, eggs, plants, berries, bark, and
leaves that make up the gorilla diet. In the wild or
in captivity gorillas will eat meat, but do not seek
it or kill other animals, except in self defense.
When the terrain permits, females and young
sleep on tree platforms of branches and leaves.
Mature males nest at the bases of trees occupied
by other band members.
Female gorillas, like women, menstruate
monthly and mate successfully at any time. Pregnancy
lasts 9.5 months and yields one or two
young. Baby gorillas are suckled for a year. They
are adults ten to eleven years later. Wild gorillas
live for thirty to forty years.Afew captive gorillas
have attained more than fifty years.
Gorilla Language and Intelligence
Gorilla language is composed of several sounds.
Hooting signals alarm or indicates unusual events.
Hooting by a silverback gains immediate attention
from all band members. Other language
sounds include sharp grunts that discipline young
gorillas and low growls signifying pleasure. All
gorillas beat their chests. In males, this is a symbol
of power and intimidates other creatures.
The mental capacity of gorillas was long
thought inferior to chimpanzees. Their intelligence
is still being explored and testing is changing
experimenters' opinions. Different techniques
are needed to train gorillas, who are not as curious
as chimpanzees. Trained correctly, gorillas have
better memories and problem-solving skills than
chimpanzees. They also discriminate between
geometric shapes better. In addition, it is reported
that they are most likely to perform tasks associated
with intelligence out of interest, not for rewards.
In exploration of communication via
American Sign Language (ASL), some gorillas
have mastered over one hundred words.
Gorillas' Endangered Status
Gorillas are close to extinction because of intrusion
on their habitat of farmers, animal herders,
and hunters. In the early 1970's, the estimated gorilla
population was one thousand. About 25 percent
were in Zaire's Kahuzi-Biega National Park
(KBP) and 40 percent in its Mount Virunga area
(MVA). The rest were scattered but relatively numerous
in Rwanda's Parc des Volcans and Uganda's
Gorilla Game Reserve.
In 1980, the number of gorillas in KBP was unchanged
and those in MVA had dropped 40 percent.
The implied decline, which may be continuing,
is explained by increased farming and cattle
herding in gorilla habitats. Also, killing and
poaching of elephants and buffalo causes these
animals to move into gorilla habitats, cutting
down food sources for the great apes. The
Rwandan Mountain Gorilla Project has slowed
the decline in Rwanda. Similar efforts are in place
elsewhere.
Classification:
Kingdom: Animalia
Subkingdom: Bilateria
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Primates (apes, monkeys, and humans)
Family: Pongidae
Genus and species: Gorilla gorilla
Geographical location: Equatorial West Africa
Habitat: Lowland and highland forests
Gestational period: Nine months
Life span: Thirty to forty years in the wild, up to
fifty years in captivity
Special anatomy: Long arms used to walk on all
fours
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