Spider Monkey

Spider monkeys are the new world monkeys (the monkeys that are five families of primates found in the tropical regions of Mexico, Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae). The spider monkeys belong to the genus Ateles, are a part of the subfamily Atelinae, and family Atelidae. They are found in the tropical forests of Central and South America, from southern Mexico to Brazil. The genus contains a total of seven species - all under threat. Out of the seven spider monkey species, the brown spider monkey is critically endangered. The spider monkeys are also notable for their ability to be easily bred in captivity.

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Spider Monkey - Description

The spider monkeys are the largest new world monkeys - their long limbs and long prehensile tails makes them so. They live in the upper layers of the rainforest, and forage in the high canopy from 25 to 30 m (82 to 98 ft). Due to their large size, they need large tracts of moist evergreen forests. They also prefer undisturbed primary rainforest. A spider monkey eats fruits, leaves, flowers, and insects. They are social animals who live in a group of upto 35 individual spider monkeys but splits to forage during the day. The spider monkeys are not only the largest new world monkeys but also the most intelligent ones. They bark when threatened and can produce a wide range of sounds. 

Spider Monkey - Scientific Classification

Spider Monkey - Taxonomic Classification

The genus Ateles consists of seven species and seven subspecies. 

• Family - Atelidae

Sub family - Alouattinae (howler monkeys) and Atelinae (spider and woolly monkeys)

• Genus Ateles: Spider Monkeys

• Ateles paniscus: Red faced monkey

• Ateles belzebuth: White fronted spider monkey

• Ateles chamek: Peruvian Spider monkeys

• Ateles hybridus: Brown spider monkey

• Ateles marginatus: White cheeked spider monkey

• Ateles fusciceps: Black spider monkey

• Ateles fusciceps fusciceps: Brown headed spider monkey

• Ateles fusciceps rufiventris: Colombian spider monkey

• Ateles geoffroyi: Geoffroy's spider monkey

• Ateles geoffroyi grisescens: Hooded spider monkey

• Ateles geoffroyi yucatanensis: Yucatan spider monkey

• Ateles geoffroyi vellerosus: Mexican spider monkey

• Ateles geoffroyi geoffroyi: Nicaraguan spider monkey

• Ateles geoffroyi ornatus: Ornate spider monkey

• Genus Brachyteles: Muriquis (woolly spider monkeys)

• Genus Lagothrix: Woolly monkeys

• Genus Oreonax: The yellow-tailed woolly monkey

Anatomy and Physiology

The largest new world monkey - black-headed spider monkeys weigh around 11kgs for males and 9.66kgs for females. They are around 35 – 66 cm (14 – 26 inches) long, excluding the heavily furred tail, which is longer than the body. Their tail is deftly prehensile, which may grow up to 89 cm (35 in); have very flexible, hairless tips and skin grooves similar to fingerprints. This adaptation to their strictly arboreal lifestyle acts as their fifth hand. Unlike many monkeys, they do not use their arms for balancing when walking. Instead, they rely on their tails. Their hands are long, narrow and hook-like, and have reduced or non-existent thumbs and their fingers are elongated and recurved.

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Their coat, of variable length and fineness, ranges among the several species from gray to reddish, dark brown, or black. They are also found in white colour in a rare number of specimens. They have black hands and feet. They have small heads with hairless faces. Another distinguishing feature of the spider monkeys is their nostrils which are very far apart.  

Behaviour

The spider monkeys always roam in groups of 15 - 25 and up to 30 - 40. During the day, their groups break into sub groups. The size of the sub groups depend on the competition for food and the risk of predation. The average sub group size varies from 2 - 8 to 17 spider monkeys. The female monkeys, rather than males disperse at puberty to join new groups. The male monkeys tend to stick together for their whole lives and hence, the males have closer bonds than the females. The strongest social bonds are formed between females and their young offspring. 

They communicate using postures and stances. When they are threatened, they start barking which is similar to the barking of dogs. When they are approached, they climb to the end of the branch and start shaking the branch to scare away the possible threat. They may also scratch their limbs or body with various parts of their hands and feet. The seated monkeys may sway and make noise. They also defecate and urinate towards the intruder. 

The spider monkeys are active during the day and they sleep carefully during the night in the selected trees. Their groups are led by a female who is responsible for planning an efficient feeding route every day. The spider monkeys avoid using the upper canopy of the trees for locomotion. 

At 107 grams, the spider monkey brain is twice the size of the brain of a howler monkey of equivalent body size. This is the result of the spider monkeys' complex social system and their frugivorous diets, which consist primarily of ripe fruit from a wide variety of plants. This requires the monkeys to remember when and where the fruit can be found. The spider monkey species lives around 20 - 27 years or sometimes more, and the females give birth once in every 17 to 45 months. 

Presumably, the oldest living spider monkey in captivity - Gummy, is presumed to have been born as a wild spider monkey in 1962. It currently resides at Fort Rickey Children's Discovery Zoo located in Rome, New York.

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Diet

The diet of the spider monkeys consists mainly of fruits and nuts - almost 70 - 85%. The spider monkeys can live for long periods on only one or two kinds of fruits and nuts. They swallow the whole fruits and the seeds of the fruits are eventually excreted and fertilized by the feces. The diet of the spider monkeys changes their reproductive, social, and physical behavioral patterns. Mostly, feeding happens from dawn to 10 am and afterward, the adults rest while the baby spider monkey plays. If food is scarce, they eat insects, leaves, bird eggs, bark and honey. 

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Reproduction

The female monkey chooses a male from her group for mating. Their gestation period ranges from 226 to 232 days and each female bears only one offspring on average - every three to four years. Till the age of six to ten months, the infants rely completely on their mothers. A mother carries her infant around her belly for the first month after birth and then on her lower back. The mother monkeys are generally attentive and they take very good care of the baby spider monkeys and are protective in nature. The male spider monkeys are one of the few primates who do not have a baculum. 

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Fun Facts

• According to the fossil remains, the earliest living ancestors of the spider monkey date back during the Pleistocene period, as far as 11,700 years to 2.5 million years ago.

• When the spider monkeys face an intruder, they break off tree branches and twist them so that itl drops towards the potential threat on the ground. 

• The long, prehensile tails of the spider monkey species end in leathery tips with distinct grooves -- very similar to human fingerprints. 

The Red Faced Monkey

The Ateles paniscus, or the red faced spider monkey or the Guiana spider monkey is a species of spider monkey that are found in the rain forests in northern South America. This species is listed as vulnerable on the  International Union for Conservation of Nature (IUCN) Red List of Threatened Species or the Red Data Book as they face issues with hunting and habitat loss. They have long, black hair and a red or pink face. Infant red faced monkeys are born with dark faces, which lighten as they grow. Sexual dimorphism in the species is small. The head-body length of the male red faced monkey is 55.7 centimetres (21.9 in) on average, and the female monkey is around 55.2 cm (21.7 in) in length. The male monkey weighs around 9.1 kg and the female monkey weighs around 8.4 kg. The tail is prehensile and its fingers and limbs are long, agile and strong.

The red faced monkeys are found in undisturbed primary rainforests, in northern Brazil, Suriname, Guyana, French Guiana and Venezuela. They have the ability to climb and jump and hence, tend to live in the upper layers of the rainforest trees and forage in the high canopy. They are protected in the Amazon under the Amazon Animal Protection Act of 1973.

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Finger Spider Monkey

As the name implies, the finger spider monkeys are true monkeys. They are the smallest monkey and one of the smallest primates in the world. They are commonly known as pygmy marmoset or thumb monkeys, and belong to genus Cebuella. They are found in evergreen and river-edge forests and are a gum-feeding specialist, or a gummivore. Around 83% of the finger monkey population lives in stable troops of two to nine individuals, and includes a dominant male, a breeding female, and up to four successive litters of offspring. The finger monkey has a head-body length ranging from 117 to 152 mm (4.6 to 6.0 in) and a tail of 172 to 229 mm (6.8 to 9.0 in). The average adult body weight of the monkeys are just over 100 grams with the only sexual dimorphism of females being a little heavier. The colour of their fur is a mixture of brownish-gold, grey, and black on its back and head and yellow, orange, and tawny on its underparts. Their tail has black rings and their face has flecks of white on their cheeks and a white vertical line between their eyes. The finger spider monkey has many adaptations for arboreal living including the ability to rotate its head 180° and sharp claw-like nails used to cling to branches and trees. Their dental morphology is adapted to feeding on gum, with specialised incisors that are used to gouge trees and stimulate sap flow. Their cecum is larger than usual to allow for the greater period of time gum takes to break down in the stomach. The pygmy marmoset walks on all four limbs and can leap up to 16 ft between the branches. 

The finger spider monkeys are found in the western Amazon Basin, in Brazil, Colombia, Ecuador, Peru, and Bolivia. Their distribution is often limited by the rivers. They typically live in the understory of the mature evergreen forests and often near rivers. Their population density is correlated with food tree availability. They have a special diet of tree gums. They gnaw holes in the bark of appropriate trees and vines with their specialized dentition to elicit the production of gum. When the sap puddles up in the hole, they lap it up with their tongue. They also lie in wait for insects and butterflies, which are attracted to the sap holes. They supplement their diet with nectar and fruit. The Pygmy marmosets or the finger spider monkeys have adapted insect-like claws, known as tegulae, to engage in a high degree of claw-clinging behaviors associated with plant exudate exploitation. The finger spider monkeys are threatened by habitat loss in some areas of its range, and by the pet trade. 

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Mexican Spider Monkey

The Mexican spider monkey is the subspecies of Geoffroy's spider monkey or the black spider monkey. They are from Mexico and Central America, native to Mexico, Guatemala, Honduras, Nicaragua and El Salvador. They are listed as critically endangered by the IUCN due to 80% population decline in the last 45 years, mostly due to a large amount of habitat loss. 

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