Monkeys are primates. They share this classification with lemurs, great apes and humans. There are over 150 different monkey species spread around the world's warmer regions. These creatures are identified by their grasping hands, their eyes that are positioned at the front of their heads, and their highly-developed brains. Some monkeys such as the howlers have prehensile tails that allow them to move through the trees with athletic agility. Monkeys can generally be divided into Old World monkeys and New World monkeys. Old World monkeys are found in Africa and Asia while New World monkeys live in Central and South America.
Old World Monkeys
Old World monkeys range across Asia and Africa. They inhabit tropical rainforests, the savannah and the mountains. There are over 75 species of Old World monkeys. They are larger than their New World counterparts and can be divided into two groups - the Cercopithecinae and the Colobinae. The Cercopithecinae include baboons, mandrills and macaques. Although this family may sleep in the rainforest at night they cannot be truly considered rainforest monkeys as they forage by day on the savannah.
The second family of Old World monkeys are the Colobinae. These arboreal monkeys are also known as leaf-eating monkeys and they occupy the tropical rainforests of the Old World. They do not possess cheek pouches. Unlike the omnivorous Cercopithecine monkeys, the Colobinae are exclusively plant-eaters. They have specialised stomachs that break down cellulose and they possess elongated intestines. Among the species of Colobinae are the colobus of Africa, the South Asian langur, and the proboscis monkey of Borneo. Adults of this latter species develop very long noses.
New World Monkeys
New World monkeys are found in the rainforests of Mexico, Central America and South America. Unlike their Old World cousins, New World monkeys are primarily arboreal, meaning that they live in the branches of the rainforest canopy. These monkeys are herbivores although some may eat insects occasionally. Capucin monkeys are known to hunt crabs and clams. For the most part, New World monkeys are much smaller than those found in the Old World. There are over 50 species of New World monkeys that can be divided into two families -- the Callitricidae and the Cebidae.
This family of New World monkeys include marmosets and tamarins and are only found in the rainforests of Central and South America. The Callitricidae are the smallest of all monkeys. Pygmy marmosets weigh less than 113gr. Other species include the white-lipped tamarin, the cotton-top tamarin, the silvery marmoset and the finger monkey. In total there are at least 26 species in this family. The Callictricidae are considered primitive monkeys due to their lack of opposable thumbs and their inability to change their facial expressions. They do not have prehensile tails. They rely on their four limbs that give them the agility of a squirrel in a tree, making them well-adapted to their rainforest environment. They enjoy tree sap, flower nectar and occasionally insects. A new species of tamarin, the Mura saddleback tamarin was discovered in the Brazilian Amazon in 2009.
The Cebidae family are the most common New World monkeys. They are all rainforest-dwellers living in the canopies of Mexico, Central America and South America. The Cebidae can be divided into four subfamilies -- capachin and squirrel monkeys; night and titi monkeys; howler and spider monkeys; and uakaris and sakes. Their prehensile tails make these monkeys adept for a life in the rainforest canopy where they manoeuvre through trees and branches with athletic prowess. Most of the species feed at dawn and dusk while the night monkey is the only monkey species in the world that feeds at night. There are six species of howler monkeys and all are known for their very loud vocalisation emanating from the treetops. Spider monkeys are the most primitive of the Cebidae. Their name comes from the way that they resemble spiders when they hang by their tails.