The term "monkey" is used to denote any
higher primate (suborder Anthropoidea) that
is not an ape. Thus, it includes both members of
the New World monkeys (infraorder Platyrrhini)
as well as the Old World monkeys (infraorder
Catarrhini, superfamily Cercopithecoidea). Monkeys
have little in common with each other except
for the fact that most are quadrupedal, but this
does not eliminate all other primates. It is unclear
where the name "monkey" originated, although a
common interpretation is that it relates to the medieval
term "moneke", meaning manikin.
Old World (Catarrhine) Monkeys
The OldWorld monkeys are the largest and most
diverse family of primates, covering about ninetyfive
species and ranging over most of Africa, Asia,
and Indonesia. The name Catarrhine means
"downward-nosed", referring to the fact that the
nostrils are close together and point forward and
down. Catarrhine monkeys include macaques,
mangabeys, baboons, mandrills, velvet monkeys,
guenons, colobuses, proboscis monkeys, and langurs.
There are two subfamilies: the leaf-eating,
arboreal Colobinae (examples include the colobus
and the langur), and the omnivorous, often
ground-dwelling Cercopithecinae (including the
baboons, mandrills, macaques, and guenons). The
Colobinae have a rather complex stomach and digestive
system, whereas the Cercopithecinae have
a simple stomach combined with cheek pouches
in which food can be stored.
The macaques are the greatest in number
among the OldWorld species, as well as the most
widespread. The most northerly is the Japanese
macaque, which can live in cold, snowy climates.
Other macaques live in dry, almost desertlike conditions
in the tropics.
Old World species are generally larger than
New World species, and there is considerable
sexual dimorphism. Most have bare buttock
pads, which may be brightly colored. Their tails
are seldom fully prehensile, and may be significantly
reduced in size. Almost all are active during
the day, with excellent vision, hearing, and
sense of smell. They communicate almost entirely
by sight and sound, displaying a wide range of
calls. Many display a range of facial expressions,
used for communication with their own species
as well as with other species nearby. Most are
fully arboreal, but baboons are ground feeders,
and macaques live both on the ground and in the
trees.
When more than one species of monkey dwells
in the same locality, the various species generally
occupy different vegetation levels in order to
avoid competition. This behavior is known as arboreal stratification.
Most authors recognize four
layers of vegetation in the tropics: the ground
layer, lower canopy, middle canopy, and upper
canopy. For instance, in the African guenons
(Cercopithecus spp.), DeBrazza's monkey lives at
the ground level, the red-tailed monkey sleeps in
the middle canopy but spends the day on the
ground, the blue guenon lives in the upper canopy
but forages in the middle, and the Diana monkey
lives solely in the upper canopy.
New World (Platyrrhine) Monkeys
The New World monkeys are a highly successful
and diversified group colonizing Central and
South America. The term usually refers to the
infraorder Platyrrhini, meaning "flat-nosed." As
compared with the Catarrhine monkeys, the nostrils
of the Platyrrhines are broadly separated and
usually point to the sides. Members of the
Platyrrhines include capuchins, howler monkeys,
sakis, woolly monkeys, squirrel monkeys, and
uakaris, a total of about forty-five species.
NewWorld monkeys have long, thin fingers on
each hand, with flattened or curved nails. Although
their thumbs are not opposable, as they
are in the human, the big toe can be opposed
against the other toes for gripping branches
tightly.NewWorld monkeys are excellent runners
and jumpers, swinging and leaping through their
densely wooded habitats. Their tails are fully prehensile;
they can grasp objects at the tip and curl
around a branch and support the full body weight
of the animal. In almost all cases, the tail is at least
as long as the head and body, and it acts as a balancing
organ, often being held in a curled pattern.
None of the New World monkeys are ground
dwellers, unlike the baboons and other OldWorld
monkeys. None of them have cheek pouches, and
sexual dimorphism is rarely seen. New World
monkeys are gregarious and live in family-based
groups with much vocal and visual communication.
They have highly developed olfactory organs
that may also be used for communication.
Males of many species contain a glandular patch
on the sternum (breastbone) which they rub
against tree branches to act as scent markers.
Marking by means of urine and feces is also common.
For instance, night monkeys coat their
hands and feet with urine so that they leave a telltale
scent wherever they go.
Families are well developed in most species of
monkeys, although females do most of the caring
for their offspring. Mothers usually carry their
young on their backs until they are ready to move
through the canopy on their own. Group size
seems to depend primarily on the productivity
and abundance of the foods typically eaten by the
species. Species that live in small groups tend to
feed on small, scattered, or scarce resources such
as insects, small vine fruit, or newly emerged
leaves of bamboo. Species that form large groups
use abundant or clumped resources, such as fruits
on large fig trees. Small family groups are typically
one to three animals, while large groups may
involve seven to twenty members.
Classification:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Primate
Suborder: Anthropoidea
Families: Cercopithecidae (Old World monkeys,
eight genera, forty-five species); Cebidae
(New World, capuchin-like monkeys, eleven
genera, and thirty species)
Geographical location: Africa and Asia (Catarrhines),
Central and South America (Platyrrhines)
Habitat: Mostly forests, some grasslands
Gestational period: Old World monkeys, 5 to 6
months;NewWorld monkeys, 4 to 7.5 months
Life span: OldWorld monkeys, twenty to thirtyone
years; New World monkeys, twelve to
twenty-five years
Special anatomy: Opposable thumbs, forwardfacing
eyes for binocular vision, large brain
case
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