Geoffroy's spider monkey (Ateles geoffroyi) is one of the largest New World primates, with a slender body, elongated limbs, and a highly developed prehensile tail that acts as a fifth limb. Their morphology is adapted to arboreal life: the absence of opposable thumbs allows them to hang efficiently and move quickly between branches. Their fur can vary in color from black, brown, and reddish, with a characteristic light facial mask around the eyes. Their diet is predominantly frugivorous, especially centered on figs, although it also includes leaves, seeds, flowers, and insects. They are social and intelligent animals that play a key role in ecosystems as seed dispersers. They are found in tropical and subtropical forests, mainly humid, with high vegetation density, where they take advantage of the canopy to move and feed. They have a low reproductive rate, which represents a vulnerability to human threats.

It is a diurnal, strictly arboreal primate, known for its agility and speed when moving through the forest canopy using brachiation, swinging its arms and prehensile tail. It lives in complex fusion-fission social groups, in which subgroups separate and reunite throughout the day depending on food availability. Females typically leave their natal group upon reaching sexual maturity, while males remain in the same group for life. Communication is achieved through vocalizations, body postures, and facial expressions, including loud squeals, moans, and alarm calls. Social relationships are marked by hierarchies and alliances, and frequent interactions such as grooming are observed. They spend a good part of the day feeding, resting, and monitoring their surroundings. They are curious and intelligent, capable of problem-solving and memorizing complex food routes.

Geoffroy's spider monkey is classified as Endangered (EN) by the IUCN due to a combination of severe threats, including habitat loss and fragmentation, hunting, and illegal trade. Deforestation for agricultural crops, livestock, and urbanization has drastically reduced its range, isolating populations and hampering reproduction. Furthermore, capture for the pet trade remains common in some regions, despite being prohibited by law. Its listing in CITES Appendix I prohibits international trade, reflecting its global vulnerability. Due to its slow reproductive cycle, with a single offspring every two to four years, populations cannot easily recover. Monitoring, education, and captive-breeding programs (such as the EEP) have been implemented in several protected areas, but their success depends on effective habitat protection and compliance with environmental legislation.