This is the smallest monkey in the world. It weighs only 100 grams. It’s body length is ranging from 117 to 152 millimeters, and it’s tail tail for about 172 to 229 millimeters. This little fella lives in rain forests of the western Amazon Basin in South America. It’s typical habitat is a forest with a river near. The most interesting fact about this monkey is that it feeds on tree gum. It supplements its diet with nectar and fruit. They usually live in groups ranging from 2 to 9 members.