The **smallest monkey in the world** is the Pigmy Marmoset, which is found in the rain forests of the Amazon. It can grow up to six inches (15 cm) in size, and weigh up to 5 ounces (140 g). It is considered the world’s smallest monkey due to its short length and light weight.
The Pigmy Marmoset is arboreal and spends most of its time in the rainforest canopy, living in small family groups and subsisting on a diet of fruit, nuts, insects, nectar, and sap from trees. Its ability to spectacularly jump from branch to branch makes it fit extremely well in its tree-dwelling environment.