Spider Monkeys: 7 facts about this incredibly intelligent creature

Spider monkeys, denizens of the forest canopy, are famous for their graceful, long limbs. But these monkeys also engage in complex (and adorable) social behaviors, including wrapping their tails around each other, and hugging after time apart.

These behaviors are perhaps a mark of their incredible intelligence. The primates are considered the third most intelligent non-human primate after orangutans and chimpanzees. But as their forest habitats are liquidated, they face extinction.

What is a Spider Monkey?

Spider monkeys are small, fruit-eating, arboreal monkeys in the genus Ateles.

There are seven species of spider monkey, most of which weigh in at about 20 pounds. They are social animals and congregate in groups and communicate through diverse vocalizations, hugging, tail holding, and, less charmingly, defecating, according to the New England Primate Conservatory website.

Their numbers are declining. All spider monkey species are listed as Vulnerable, Endangered, or Critically Endangered by the International Union for Conservation of Nature and Natural Resources (IUCN).

These are the seven species:

• Black-faced black spider monkey (Ateles chamek): Endangered
• Brown-headed spider monkey (Ateles fusciceps): Endangered
• Geoffroy's spider monkey (Ateles geoffroyi): Endangered
• Guiana spider monkey (Ateles paniscus): Vulnerable
• Brown spider monkey (Ateles hybridus): Critically endangered
• White-bellied spider monkey (Ateles belzebuth): Endangered
• White-cheeked spider monkey (Ateles marginatus): Endangered

Why are they called Spider Monkeys?

With their unusually long, skinny limbs, and powerful, prehensile tails, spider monkeys cruise smoothly through the forest canopy. Their four-fingered hands are adapted to swinging about, unencumbered by a thumb, and they use their tail as an additional limb as they travel.

“Spider monkeys can often be seen hanging upside down from branches from their tail and limbs, strongly resembling a spider,” Juliana Rossi de Camargo, the Latin American Conservation Officer at Rainforest Trust tells Inverse.

Where are Spider Monkeys from?

Different species of spider monkey hail from different regions of Central and South America.

Geoffroy's spider monkey can also be found in Mexico.

They tend to stick to forested areas, as they primarily get around through the trees.

What makes Spider Monkeys so special?

For one, these monkeys are ecosystem engineers.

As primarily fruit eaters, these creatures distribute seeds throughout the forest. The path through a spider monkey digestive tract can soften the outer layer of the fruit seeds, too — a process crucial for some tree species to germinate, according to the New England Primate Conservatory. Spider monkey feces also help fertilize the forest floor.

For another, they are very smart. In 2006, researchers conducted an analysis of existing primate intelligence research and concluded spider monkeys ranked third in overall intelligence among non-human primates, making them the cleverest monkeys of the Americas.

Spider monkeys' intelligence has even inspired a type of computer algorithm called a Spider Monkey Optimization algorithm.

How many spider monkeys in the wild?

The data are spotty at best. The IUCN Red List database — often a reliable source of information about populations — lists a series of population density studies, but not overall numbers. The problem is researchers just don't know how many of these monkeys are out there.

“It is difficult to estimate the global population size of each species of spider monkey due to their wide ranges and the lack of comprehensive research,” Rossi de Camargo says.

Each species is in a slightly different situation, but IUCN estimates population declines of 50 or 80 percent in some of the spider monkey species over just three generations.

There may be as few as 250 brown-headed spider monkeys left in the wild, according to the Rainforest Trust.

How many spider monkeys are in captivity?

This is also difficult to know. Inverse could not locate any kind of centralized resource regarding spider monkeys in captivity. Part of the issue is spider monkeys are often taken from the wild to feed the illegal pet trade, so there may be many in captivity that are not documented.

According to the Belfast Zoo, there are 300 Columbian spider monkeys (a subspecies of brown-headed spider monkey) living in zoos across the world, but again, for all seven species, exact numbers are lacking.

What has caused spider monkey numbers to dwindle?

Different species of spider monkeys are threatened by different things, but there are some recurring themes across the species.

They are:

• Habitat loss
• Forest use
• Hunting
• The pet trade

“Habitat loss is the primary threat to spider monkey populations in the wild. Deforestation rates are increasing rapidly due to residential and commercial development, agricultural expansion, and the extraction of forest resources. In some areas, spider monkeys are also threatened by hunting and the pet trade,” Rossi de Camargo says.

Spider monkeys only reproduce every two to five years. Species which reproduce slowly have a harder time maintaining and recovering their populations when disturbed.

Any conservation efforts ongoing?

On their website, the World Wildlife Federation states they are working on creating protected areas in Guiana spider monkey habitat and promoting responsible logging through Forest Stewardship Council (FSC) certification in non-protected regions.

Rossi de Camargo agrees that protected areas are necessary, but caution that “many [reserves] lack sufficient resources to ensure effective management.”

But it is not all bad news for these special primates. There is some success in their conservation tale.

Two subspecies of Geoffroy's spider monkey were recently added to the Convention on International Trade in Endangered Species (CITES), which prohibits buying and selling the monkeys internationally, Rossi de Camargo says.

And in an area of Ecuador where hunting of the brown-headed spider monkey has stopped, the population has rebounded, the IUCN reports.

Rainforest Trust is collaborating with the Ecuadorian conservation organization, Cambugán Foundation to create a 1729 acre protected area in Tesoro Escondido to protect brown-headed spider monkey habitat, according to the organization's website. The plan is to create sustainable chocolate manufacturing in the buffer zones around the protected area, so local cacao farmers can access higher “fair trade” prices by practicing sustainable chocolate production.

This kind of local action shows how small steps to protect our fellow animals can potentially benefit our species, too.