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Spider Monkey Facts: All Genera of the Subfamily Atelinae

Spider monkey is any of seven species of New World monkeys in the genus Ateles. The genus, together with the woolly spider monkey (Brachyteles), woolly monkey (Lagothrix; also called the muriqui), and yellow-tailed woolly monkey (Oreonax), make up the subfamily Atelinae, of the family Atelidae, in the order Primates, class Mammalia. This article addresses all genera of the subfamily Atelinae.

Physical Characteristics and Habitat

Yucatan Spider Monkey

Yucatan Spider Monkey

Atelines have long, spiderlike limbs and a head-and-body length of 15 to 25 inches (38 to 63.5 cm), with a prehensile tail that is 20 to 35 inches (50 to 90 cm) long. In the wild individuals normally attain a weight of about 13 pounds (6 kg), although captives may reach 18 pounds (8 kg). However, members of the largest species -the black-headed spider monkey (A. fusciceps)- can reach of weights of 24 lb (11 kg).

The animal's long, coarse coat is usually a shade of gray or brown. Some species, such as the Mexican spider monkey (A. geoffroyi vellerosus) and the white-fronted spider monkey (A. belzebuth), have white fur covering the abdomen. In many cases the face is black with white rings around the eyes.

The red-faced, or Guiana, spider monkey (A. paniscus) sports a hairless red or pink face, however, and the white-cheeked spider monkey (A. marginatus) has white fur on the forehead and cheeks. Like female spotted hyenas, female spider monkeys have a greatly enlarged clitoris that resembles the male penis.

Atelines are indigenous to the rain forests and montane forests of Mexico, Central America, and South America. The monkeys remain primarily near the top of the forest canopy, where they are highly agile. Their disproportionately long limbs terminate in long, narrow hands with curved fingers and reduced thumbs.

These lanky limbs and hooklike fingers, in combination with their prehensile tails, enable spider monkeys to efficiently grasp branches and swing or jump from tree to tree. When they do walk, spider monkeys rely on their tails, not their arms, for balance.

Reproduction and Lifespan

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Members of Atelinae appear to have no regular breeding season. Males reach sexual maturity at about 5 years of age, whereas females are capable of breeding by about age 4. A female Ateles will select one male from her group for mating, while reproduction among Lagothrix is promiscuous, with both males and females having more than one mate at a time.

In general, females give birth to one offspring every two to four years, following a gestation period of approximately 230 days. Males do not assist in raising the young, and infants are completely reliant on their mothers until six to ten months of age. During this time, mothers will move about with their offspring clinging to their bellies or backs. In captivity Ateles has been known to live for more than 30 years.

Behavior and Diet

The atelines are arboreal and diurnal. They typically eat early in the day, consuming insects, fruits, nuts, other plant materials, and occasionally bird's eggs. They rest or play for the remainder of the day.

Members of all genera move with agility through the trees, swinging from branch to branch. They communicate by loud shrieks and calls, which can resemble a dog's bark, and by postures.

When feeling threatened, for example, a spider monkey may scurry to the end of a branch and either sit and sway or shake the branch violently, possibly to scare off the possible threat. Sometimes they will break off nearby branches and throw them toward an intruder.

The monkeys of Atelinae exhibit a complex social structure, living in groups of 15 to 30 individuals or more. Groups of Ateles are thought to be directed by a lead female, while those of Lagothrix tend to be governed by an alpha male. The groups break up into smaller subgroups of two to eight members to forage by day and to sleep, in carefully selected trees, by night.

Environmental Status

Some indigenous peoples hunt spider monkeys for food, resulting in the near or complete decimation of certain populations. Additionally, spider monkey populations have declined precipitously due to habitat destruction from encroaching land development. The International Union for Conservation of Nature (IUCN) classifies most ateline species as endangered and three species -the variegated spider monkey (A. hybridus), the brown-headed spider monkey (A. fusciceps), and the northern muriqui (B. hypoxanthus)- as critically endangered.

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