Black-handed Spider Monkey

Ateles geoffroyi

Range: Central and South America

Habitat: Tropical rain forests.

Habits: They live in large groups, called troops, composed of males, females and babies. These troops are partly territorial, keeping within their own area at night, but scattering over a wide range in search of food during the day. Spider monkeys have no thumbs, so their grasping is done with four fingers. They travel through the trees as fast as a man can run on the ground, using a method of locomotion called brachiation: arm over arm swinging through the branches. A thumb would almost be an encumbrance in brachiating, and scientists believe that, as the fingers elongated, the thumb gradually disappeared. This allowed the hands to form hooks for branch swinging.

Prehensile Tail: This tail functions as a fifth arm. The underside of the tail has no hair and is lined with ridges much like our own fingertips. This gives the monkey a good grip and keeps him from slipping. The ridges also increase traction in the tail tip for picking up small objects. Spider monkeys use their tail just as they use their hands. The tail also aids in balance and can support the monkey’s entire body if it wishes to “dangle,” leaving the hands and feet free.

Reproduction: Spider monkeys give birth at any time of the year. Usually one baby is born after a gestation period of about 7.5 months. The mother will carry her baby close to her chest until it is old enough to travel on her back.