Spider monkey

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Spider monkeys
Black-headed Spider Monkey (Ateles fusciceps)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Atelidae Subfamily: Atelinae Genus: Ateles E. Geoffroy, 1806
Type species
Simia paniscus Linnaeus, 1758
Species
Ateles paniscus Ateles belzebuth Ateles chamek Ateles hybridus Ateles marginatus Ateles fusciceps Ateles geoffroyi

Spider monkeys are New World monkeys of the family Atelidae, subfamily Atelinae. Found in tropical forests from southern Mexico to Brazil, spider monkeys belong to the genus Ateles; the closely related woolly spider monkeys, are in the genus Brachyteles.

As they require large tracts of undisturbed forest and specialize on ripe fruits, spider monkeys may be considered an indicator species; the monkeys are threatened by habitat destruction through continued growth in South American agriculture.

A recent comparative intelligence comparison gives spider monkeys a value a little above gorillas, so it is reasonable to believe that spider monkeys are among the most intelligent New World monkeys.

Overview

Spider monkey are New World monkeys. New World monkeys are one of three major informal groups of the biological order Primates, the other two groups being (1) prosimians and (2) monkeys and apes of the Old World. Together, the New World monkeys and the Old World monkeys and apes are considered to be "higher primates," or simians (infraorder Similformes), while the prosimians (such as lemurs) are considered to be the "lower primates." The term monkey thus refers to any simian that is not an ape or any primate that is neither an ape or a prosimian. In reality, monkeys are not a single coherent group and therefore do not have any particular traits that they all share.The New World monkeys are found in Mexico, Central America, and South America, and the Old World monkeys are located in Africa, central to southern Asia, Japan, and India.

There are four families of New World monkeys: Cebidae, Aotidae, Pitheciidae, and Atelidae (Groves 2001). The four families are ranked together as the Platyrrhini clade. All New World monkeys differ slightly from Old World monkeys in many aspects, but the most prominent of which is the nose. This is the feature used most commonly to distinguish between the two groups. The scientific name for New World monkey, Platyrrhini, means "flat nosed," therefore the noses are flatter, with side facing nostrils, compared to the narrow noses of the Old World monkey.

Most New World monkeys have long, often prehensile tails. Many are small, arboreal (live in trees), and nocturnal (active at night). Unlike most Old World monkeys, many New World monkeys form monogamous pairs, and show substantial paternal care of young.

Spider monkeys belong to the Atelidae family with the howler and woolly monkeys. They are placed in the Atelinae subfamily with the woolly monkeys. The primary distinguishing feature of the atelines is their long prehensile tail, which can support their entire body weight. Diurnal and arboreal, they move speedily and acrobaticly through the trees using their prehensile tail. Atelines, along with their cousins the howler monkeys, are the largest of the New World monkeys.

Physical description

Disproportionately long, spindly limbs inspired the spider monkey's common name. Their deftly prehensile tails, which may measure up to 89 cm (35 inches), have highly flexible hairless tips complete with skin grooves similar to fingerprints; this adaptation to the spider monkey's strictly arboreal lifestyle grants the monkeys a fifth hand of sorts. Adults reach an average body length of 50 cm (20 inches) and a weight of 6.4 kilograms (14 pounds).

Their arms are very small, but yet very long. With legs that are on the shorter end, the monkey walks with its arms practically dragging on the ground. However, they are one of the very few kinds of monkeys that don’t rely on their arms to help them walk. They just stand and walk on 2 feet. If some trouble occurs as far as balance goes they just grab onto their tale to help them. Their hands resemble their arms, being long and narrow. Another feature to the monkey that makes it recognizable is that its nostrils are very far apart.

Spider monkeys have hook-like, narrow and thumbless hands; the fingers are elongated and recurved. The hair is coarse, ranging in colour from a ruddy gold to brown and black; the hands and feet are usually black. Heads are small with hairless faces. An unusually long labia in females may be mistaken for a penis; its function is unclear.

There is speculation that the alleged Loys's Ape is actually a large spider monkey, but this is still a matter of intense debate amongst cryptozoologists.

Feeding

A spider monkey's diet consists of about 90% fruits and nuts. They many times can live for long periods of time on only one or two different kinds of fruits and nuts. They eat the fruits of many big forest trees, and because it swallows fruits whole, the seeds are eventually passed out as free fertilizer. Most of the feeding happens between dawn and 10 o'clock in the morning. After the morning feeding the adults rest while the young play. Throughout the rest of the day they may feed infrequently until around 10 at night. If their food is low they can resort to eating insects, bark or rotting forest, and honey. The spider monkey has a unique way of getting food because there is a lead female responsible for feeding. If she cannot find enough food for the entire group they split into smaller ones to find food easier. Spider monkeys travel in groups between four and nine. Each group is closely associated with its territory. They are very picky about their space. If they are in a big group, they will spread out while eating.

Mothers and their young

A mother spider will carry a new born infant monkey around her belly for no more than the first month. After this the young monkey travels on the lower back of the mother. The young monkey wraps its tail around its mother’s and grabs on tightly to its mother's midsection.

Mother spider monkeys are very protective of their young and are generally good mothers. They have been seen grabbing their young and putting them on their backs for protection as well as to help them navigate from tree to tree. They also aid in the crossing from tree to tree by pulling branches closer together to allow easier crossing of their more independent young. Mothers will also groom their young on occasion. For the first six to ten months of a young spider monkey’s life it relies completely on its mother. Male spider monkeys have nothing to do with the raising of offspring.

Behavior and reproduction

A Panamanian spider monkey

Forming loose groups of 15-25 individuals, spider monkeys are highly agile; they are said to be second only to the gibbons in this respect. During the day, spider monkey groups break up into smaller subgroups of 2-8 individuals; this social structure ('fission-fusion') is found in only one other primate, the chimpanzee. The size of subgroups and the degree to which they will avoid each other during the day is determined by food competition and the risk of predation. Also less common in primates, females rather than males disperse at puberty to join new groups. Males tend to stick together for their whole life. Hence males in a group are more likely to be related and have closer bonds than females. The strongest social bonds are formed between females and young offspring.

The postures and stances of a spider monkey serve to communicate their intentions and observations. Examples include the postures of sexual receptivity or an attack posture.When a spider monkey sees a human coming near, it will bark loudly similar to a small dog. When a monkey is approached it will climb to the end of the branch it's on and shake it vigorously in an attempt to scare the possible threat away. The animals shake the branches with their feet, hands, or a combination while hanging from their tail. They may also scratch their limbs or bodies with various parts of their hands and feet. Seated monkeys may sway and make noise. Male spider monkeys and occasionally adult females will growl menacingly at the approach of a human. If the animal's pursuer continues to advance spider monkeys often will break off live or dead tree limb weighing up to 10 pounds and drop them towards the approaching person. The monkeys don't actually throw the branches but they will twist so the branch causing it to fall closer to the threat. The natives of the area know very well of this risk. They will also defecate and urinate toward their observer.

Spider monkeys are diurnal and spend the night in carefully selected sleeping in trees. Groups are thought to be directed by a lead female who is responsible for planning an efficient route for the day's feeding activities. Grooming is not as important to social interaction, due perhaps to a lack of thumbs.

Spider monkeys mate year round. The female monkey chooses a male from her group with whom to mate. Both male and female spider monkeys sniff their mates to check their readiness for copulation. This process is known as “anogenital sniffing.” On average, only one offspring at a time is produced from each female. The gestation period for spider monkeys ranges from 226 to 232 days.

At 107 grams, the spider monkey brain is actually twice the size of a howler monkey's of equivalent body size; this is thought to be a result of the spider monkeys' complex social system as well as their frugivorous diet, which consists primarily of ripe fruit from a wide variety (over 150 species) of plants and thus requires the monkeys to remember when and where fruit can be found. The slow rate of development in spider monkeys may also play a role, females giving birth once every 3-4 years. Spider monkeys may live for 20 years or more.

Classification

• Family Atelidae
  • Subfamily Alouattinae
  • Subfamily Atelinae
    • Genus Ateles
      • Red-faced Spider Monkey, Ateles paniscus
      • White-fronted Spider Monkey, Ateles belzebuth
      • Peruvian Spider Monkey, Ateles chamek
      • Brown Spider Monkey, Ateles hybridus
      • White-cheeked Spider Monkey, Ateles marginatus
      • Black-headed Spider Monkey, Ateles fusciceps
        • Brown-headed Spider Monkey, Ateles fusciceps fusciceps
        • Colombian Spider Monkey, Ateles fusciceps rufiventris
      • Geoffroy's Spider Monkey, Ateles geoffroyi
        • Yucatan Spider Monkey, Ateles geoffroyi yucatanensis
        • Mexican Spider Monkey, Ateles geoffroyi vellerosus
        • Ateles geoffroyi geoffroyi
        • Ornate Spider Monkey, Ateles geoffroyi ornatus
        • Hooded Spider Monkey, Ateles geoffroyi grisescens
    • Genus Brachyteles
    • Genus Lagothrix
    • Genus Oreonax

References

ISBN links support NWE through referral fees

• Groves, C. P. 2001. Primate Taxonomy. New York: HarperCollins. ISBN 156098872X
• Groves, C., D. E. Wilson, and D. M. Reeder, eds. 2005. Mammal Species of the World, 3rd ed. Baltimore: Johns Hopkins University Press. ISBN 0-801-88221-4

External links

Wikispecies has information related to:

Spider monkey

• Black Spider Monkey (Ateles paniscus)
• Primate Info Net Ateles Factsheets

Credits

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