The head and neck are generally dark brown to gray, while the back is black to gray with bluff mixed in. The under side is often orangish, but can range from white to tawny. The head and chest of this species have long tufts of hair, giving the appearance of a mane. The tail is not prehensile. Their forelimbs are shorter than their hind limbs.
Pygmy marmosets have claws on all of their digits except the great toe, which has a flat nail.
They have only two molars as opposed to the three in most other monkeys. Food Habits Pygmy marmosets gouge holes in trees and feed primarily on sap, gum, and latex. They also add spiders and insects, which are attracted to the sap from the tree, to their diet. This monkey lives in small groups, thought to be family groups, in which only one female per group breeds per season. A baculum is present in males.