These minute primates weigh an average of just over no grams (3.9 ounces), and measure 135 millimetres (5.3 inches) in body length. Despite their miniature size, they are capable of jumping impressive distances of up to five metres (16 feet) and are highly adapted for a life in the trees.
They live in the Amazon rainforest of South America and, using their long, sharp lower front teeth, gnaw holes in trees and vines to feed on sap, gum and resin. The marmosets choose one tree at a time for this purpose, making a series of holes from the bottom to the top. The sticky sap also attracts insects, which the omnivorous marmosets will eat to supplement their diet.
Pygmy marmosets are social creatures and live in small groups, usually of less than ten, with one dominant male and a breeding female. They are prey animals, and can turn their heads a full 180 degrees in order to keep watch over their surroundings for predators. They also use a series of squeaks, clicks, whistles and trills to communicate with one another over short and long distances.