White-bellied spider monkey  (Ateles belzebuth)

Description

Like all spider monkeys, the white-bellied spider monkey, also known as the long-haired spider monkey, has long, slender limbs and very mobile shoulder joints that aid in swinging hand-over-hand below branches (2) (4). The thumbs are either absent or reduced to a small stump, resulting in a hook-like hand structure that facilitates fast swinging below the branches (5). A further adaptation to this arboreal lifestyle is the extremely flexible prehensile tail that is used as an extra limb (2). The coat is black or brown, while the underparts, hindlimbs and the base of the tail are paler brownish-white (2). In one-third of the population, there is a yellowish-brown or white triangular patch on the forehead (2).

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