The pygmy marmoset is a small New World monkey native to rainforests of the western Amazon Basin in South America. It is notable for being the smallest monkey and one of the smallest primates in the world at just over 100 grams. It is generally found in evergreen and river edge forests and is a gum-feeding specialist.
The head-body length of these monkeys are ranging from 117 to 152 mm and a tail of 172 to 229 mm. The fur colour is a mixture of brownish-gold, grey and black on its back and head and yellow, orange and tawny on its underparts. Its tail has black rings and its face has flecks of white on its cheeks and a white vertical line between its eyes. This monkey has a specialized diet of tree gum. They live with their parents, twin and other siblings form cooperative care groups. They usually gives birth to twins once or twice a year.