Its arms are significantly longer than its legs, and its prehensile tail can support the entire weight of the monkey and is used as an extra limb.

Its diet consists primarily of ripe fruit and it requires large tracts of forest to survive.

As a result of habitat loss, hunting and capture for the pet trade, it is considered to be endangered by the IUCN.

Kellogg and Goldman differentiated Geoffroy's spider monkey from other species by its dark black head, hands and wrists.

Older studies by Porter, et al. indicate the howler monkeys are believed to have branched off from the other Atelides over 10 million years ago.

[6] In 2005, mammalian taxonomy reference work, Mammal Species of the World, listed five subspecies:[1] In 2015, a phylogenetic study recommended A. g. yucatanensis was a junior synonym of A. g. vellerosus.

[1][8][9] Other authorities, including Froelich (1991), Collins and Dubach (2001) and Nieves (2005), consider A. fusciceps to be synonymous with A. geoffroyi.

[6] The range of this species extends over much of Central America, encompassing Panama, Costa Rica, Nicaragua, Guatemala, Honduras, El Salvador, Belize and the south and much of the eastern portion of Mexico.

[4] Observations by local people indicate the southernmost subspecies, the hooded spider monkey, A. g. grisescens, may also occur in the portion of Colombia near the Panama border.

[11] Higher densities of Geoffroy's spider monkeys are generally found in areas containing evergreen forest.

[14] Its body color varies by subspecies and population, and can be buff, reddish, rust, brown or black.

The tail acts as an extra limb, and is used for locomotion, as well as to pick fruits and to scoop water from holes in trees.

[19] This organ, called a pendulous clitoris because of the way it dangles externally, is actually larger than the male flaccid penis.

[22] It lives in fission–fusion societies, large groups with a typical 20 to 42 members, which split into smaller subgroups to forage during the day.

[14] Geoffroy's spider monkey sometimes rubs a mixture of saliva and ground lime tree Citrus aurantifolia leaves on its fur.

[24] In addition to walking or running on four limbs and climbing, Geoffroy's spider monkey uses several forms of suspensory locomotion.

Brachiation, or swinging from the arms with assistance from the prehensile tail, is the most common form of suspensory locomotion.

[22] Sounds produced by Geoffroy's spider monkey include barks, whinnies, squeals, squeaks and screams.

[19] Several researchers have investigated the use of whinnies, which consist of between two and twelve quick increases and decreases in pitch, in more detail.

A study performed in 2007 concluded they were the third most intelligent nonhuman primate, behind only orangutans and chimpanzees, and ahead of gorillas and all other monkeys.

[26] This mental capacity may be an adaptation to spider monkeys' frugivorous diets, which require them to be able to identify and memorize many different types of foods and their locations.

[28] Large cats – jaguars and pumas – appear to be the only significant adult spider monkey predators, other than humans.

In one study at Barro Colorado Island, all males in the group were observed mating at least once over a one-year period.

[19] Geoffroy's spider monkey is listed as endangered by the IUCN, mostly due to habitat loss and capture for the pet trade.

[2] It requires large tracts of primary forest to survive, so it is vulnerable to deforestation and is sometimes hunted by humans and captured for the pet trade.