Pygmy marmoset is the smallest monkey among all monkey species in the world. The average head and body length is as short as 12 cm and their maximum tail length of 20 cm, sometimes they are not more than the length of average human finger. With these small measurements of body these mammals weights is not more than 199 grams. This attribute or feature also makes it the lightest monkey in the world as well. Their fur-like skin is buff and grey with yellow and green scheme. This smallest member of the monkey family has long hair on the head and its chest gives a look of manes. It is mostly found in the tropical forest of southeastern Colombia, northern Bolivia, eastern Ecuador, western Brazil and eastern Peru.

These are active and agile creatures, running, jumping and occasionally leaping through trees and shrubs with in their social territories ranging from 25 to 100 acres. With in these boundaries no unknown monkey from other families is allowed to enter. This small creature lives in a family like structure ranging from two to six members. These groups are made up of an adult pair and their off springs. In this family like groups the offspring producing females are the dominant ones.