Pygmy Marmosets are a species of Marmoset. The name marmoset originates from a French word for shrimp, meaning tiny, and the Pygmy is the smallest of them all. Living in the high tree tops, they live a protected gentle lifestyle.These marmosets are found in the Upper Amazon basin east of the Andes in Colombia, Ecuador, Peru, Northern Bolivia and Brazil. Living in a highly populated family lifestyle, congregating, socializing and protecting is the main base of their solitude habits.
Pygmy marmosets are the world’s smallest monkeys. Adults range around five inches (13 cm) long with an eight-inch (20 cm) tail and commonly weigh four to seven ounces. The gray fur is tuft with yellow and green speckled streaks giving it a rough effect on the head and back yet their face is hairless, having no ability to change its facial expressions. On their head and chest their long hair gives the appearance of a mane of great coloration providing great camouflage for the trees.
They are active creatures moving easily through the trees in an upright position. Their forelegs are shorter than their hind legs with claws on all digits except the big toe, helping them to cling upright to feed. Pygmy Marmosets are commonly found in groups of two to six. The group is made up of an adult pair and its offspring. Monogamy(the practice of having only one mate) is strongly shown and recognized by this species which is fairly rare in both mammals and primates.
Marmosets are usually gentle and private creatures. Mutual grooming is often seen between members of a group as part of their social bonding. Pygmy marmosets are very territorial and usually mark and defend territories from 25 to 100 acres. They mark their territory with scent glands located on the chest area. Calls, displays, and sometimes chasing away others is used in Defense of territory, but only when there is a strong threat.  
A male marmoset can mate at one year old, while the female is not fully mature until she is between 20 to 24 months. Marmosets live in family groups of 3 to 15, consisting of one to two breeding females, an unrelated male, their offspring and occasionally extended family members and unrelated individuals. Their mating systems are highly variable and can include monogamy, polygamy and occasionally polyandry. In most species, fraternal twins are born and uncommonly a female marmoset will give birth to triplets, or to a litter of four. Both parents share in the care of their offspring.Similar to other primates, marmosets are characterized by a high degree of group care for the young including sharing of food and homing. When the family moves through the trees, young marmosets cling onto the male and he carries them on his back. Just about all Adult members, except the mother, contribute to carrying young. Most groups scent mark and defend the edges of their ranges, but it is unclear if they are truly territorial, as group home ranges usually overlap. 
Marmosets are highly active, living in the upper canopy of forest trees, and feeding on insects, fruit and leaves. Each of their primary feeding sources dictates their homing ground often in holes or vines tangles together located near their feeding ground.They have long lower incisors, which allow them to chew holes in tree trunks and branches to harvest the sap inside. some species are specific feeders on the gummy sap. 
-  FONZ, National Zoo,.
-  National Zoological Park, National Zoo,.
-  Ruth Belena, Helium, date.