The pygmy marmoset is the smallest species of monkey in the world. Fully grown, they only weigh 4 to 5 ounces and are 6 inches long. The only primates smaller than pygmy marmosets are pygmy mouse lemurs and pygmy tarsiers.
The pygmy marmoset is native to the Amazon rain forest in South America, where it lives with a troop, high in trees near water. The small size of a pygmy marmoset allows it to venture out onto thin branches and gain access to higher levels of the canopy than many other animals. They eat tree gum and sap in addition to small insects. Pygmy marmosets are also called "little lions," "dwarf monkeys" and "pocket monkeys."