The name "orang-utan", commonly written in
the hyphenated form, comes from two Malay
words: orang meaning "person", and hutan meaning
"forest or jungle." Thus, Malaysian orang-utan
means "persons of the jungle." Since these animals
are very humanlike and live secretive lives in
the dense jungle, the origin of the name makes
sense. Orangutans are considered to be a threatened
species. Less than twenty thousand are believed
left in the wild.
Orangutans are the second largest of the apes,
and show marked sexual dimorphism. Malesmay
grow to be 220 pounds (100 kilograms) and females
about half that. The arms of a full-grown
male may reach a span of 7 to 8 feet (2.1 to 2.4 meters),
and their hands are longer than any other
primate. These arms and hands are ideally
adapted for the arboreal life. Comparatively, the
legs are short and weak; there is no external tail.
While adult males with arms extended (swinging
through the jungle) may appear to be enormous,
when standing erect on the ground they rarely exceed
4.5 feet (1.3 meters) in height. Females, by
contrast, reach only 3.5 feet (1.1 meters).
Habitat
Two to three million years ago, orangutans lived
as far north as China and as far south as Java. As
land bridges formed during the Ice Age, orangutans
moved south in search of a warmer climate.
Today they can only be found on the Indonesian
islands of Borneo and Sumatra.
Orangutans are the only truly arboreal apes,
spending most of their life in forest trees. Their
anatomy is well suited for this lifestyle. They walk
up trunks using irregularities in the bark to give a
grip to fingers and toes, and proceed silently
through the middle stories of the forest. These
middle stories are especially well suited for horizontal
travel, where densely growing trees poke
up into the canopy. Often vines are used for
quickly moving up and down to get to the next
horizontal branches. Orangutans do not jump;
they climb and walk the branches on all four legs.
They may also sit, recline, or hang in a variety of
positions, including suspended from both feet or
from one foot and one hand.
On the ground, orangutans are normally quadrupedal,
although they occasionally walk in the
bipedal position. Their weight is borne by
clenched fists with the palm touching the ground
(unlike gorillas and chimpanzees). Their walk is
similar to that of a dog, with diagonally opposed
limbs moving forward together.
Orangutans live alone, in pairs, or in small
family groupings. They build nests in the trees
fromgroups of small branches, bent or broken and
laid across one another, then lined with smaller
branches that are patted down into a circle of approximately
three feet in diameter. Nests are
placed ten to one hundred feet above the ground
and are difficult to spot. Nests may be built new
each night when animals are moving about, but
may remain intact for several months after being
built.
While moving and at rest in trees, the orangutan
grasps vegetable and animal matter within
its reach, testing each one as food. It prefers a
variety of jungle fruits as its principal diet, but
also eats or chews an infinite variety of buds
and leaves, flowers, bark, epiphytes, canes and
roots, honey, and even fungi. It forages and eats
at leisure, picking fruits with cupped hands
and spitting seeds and shells back out of its
mouth.
Orangutans satisfy most of their need for water
by taking it in with their moist food. When on the
ground they drink from a stream or lake by bending
over from a standing position. They have also
been seen to squat down and use their hands to
spoon the water into their mouths.
Reproduction and Development
Orangutans reach maturity at about ten years of
age, and can begin breeding at any time thereafter.
Mating begins with a male singing a song, a low
hum that increases to a deep roar before decreasing
again. Often playful wrestling, touching, and
other acts precede mating. Mating occurs in trees,
face to face, usually in a hanging position. Mating
may occur repeatedly over a period of several
weeks. The pair then separates and each goes its
own way. Males play no role in parenting.
Female orangutans have a menstrual cycle
similar to that of a human female. It lasts twentynine
days, with a slight flow of blood for three to
four days. Pregnancy lasts nearly nine months,
and newborns generally weigh 2.25 to 3.25
pounds (1.1 to 1.6 kilograms). The infant clings to
the mother's fur and the mother holds the infant
with one arm, usually over the hip. This leaves
three limbs for traveling and feeding. The youngster
nurses for two to three years, with solid food
(chewed up fruit) being added periodically. By the
end of the first year the youngster begins to explore
away from its mother, but remains within
eyesight at all times.
By age four, a youngster is pretty much on its
own, feeding itself and roaming freely. At that
point, the mother is able to mate again. Offspring
have only about a 50 to 60 percent survival rate in
the jungle, with accidents and disease striking
many young orangutans.
Orangutans are shy animals that have only one
natural enemy: humans. Currently, orangutans
are protected by law in all of their territory, but
poaching and illegal logging continue to threaten
the survival of the species. Unless large areas of
undisturbed jungle are set aside as sanctuaries,
the orangutan may have a hard time surviving in
the future.
Classification:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Primate
Family: Hominidae
Genus and species: Pongo pygmaeus
Geographical location: Sumatra and Borneo
Habitat: Dense rain forests, particularly lowland
forests
Gestational period: Eight to nine months
Life span: Thirty-five years in the wild, fifty years
in captivity
Special anatomy: Orange to red-brown hair; arm
length exceeds torso length
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