The pygmy marmoset is a small New World monkey native to the rainforests of the western Amazon Basin. It is one of the smallest primates (and is the smallest true monkey) in the world, weighing in at just 3.5 ounces. The pygmy marmoset feeds primarily on gum, or tree sap. It will also eat insects that are attracted to the gum. It also supplements its diet with nectar and fruit. They live in troops of 2-9 individuals, including a dominant male and a breeding female. Most members of the troop are family, but may include an non-related adult. The female produces twins twice a year and parental care is shared by the entire troop.