Pygmy marmoset

The pygmy marmoset, genus Cebuella, is a tiny species of New World monkey confined to the jungles of South America's western Amazon Basin. It is remarkable for being the world's tiniest monkey and one among the world's smallest primates, weighing little over 100 grams (3.5 oz). It is a gum-feeding specialist, often known as a gummivore, and is commonly found in evergreen and river-edge woods.

Approximately 83 percent of the pygmy marmoset population lives in stable troops of two to nine individuals, each with a dominant male, a breeding female, and up to four litters of young. A normal stable troop would have a median size of six people. Although most groups are made up of family members, one or two extra adult members may be present. The group communicates using a complicated system that includes verbal, chemical, and visual cues.

This monkey's diet consists entirely of tree gum. It uses its unique teeth to nibble holes in the bark of suitable trees and vines in order to induce gum formation. When sap accumulates in the hole, it licks it up with its tongue. It also waits for insects, particularly butterflies, who are drawn to the sap pores. Its diet is supplemented with nectar and fruit.