Marmoset
The marmosets (), also known as zaris or sagoin, are twenty-two New World monkey species of the genera Callithrix, Cebuella, Callibella, and Mico. All four genera are part of the biological family Callitrichidae. The term "marmoset" is also used in reference to Goeldi's marmoset, Callimico goeldii, which is closely related.
Most marmosets are about 20 cm (8 in) long. Relative to other monkeys, they show some apparently primitive features; they have claws rather than nails, and tactile hairs on their wrists. They lack wisdom teeth, and their brain layout seems to be relatively primitive. Their body temperature is unusually variable, changing by up to 4°C (7°F) in a day. Marmosets are native to South America and have been found in Bolivia, Brazil, Colombia, Ecuador, Paraguay, and Peru. They have also been occasionally spotted in Central America and southern Mexico. They are sometimes kept as pets, though they have specific dietary and habitat needs that require consideration.According to recent research, marmosets exhibit germline chimerism, which is not known to occur in nature in any primates other than callitrichids. 95% of marmoset fraternal twins trade blood through chorionic fusions, making them hematopoietic chimeras.

Etymology
Callithrix comes from Ancient Greek and means "beautiful fur".

Species list
Genus Callithrix—Atlantic marmosets
Common marmoset, Callithrix jacchus
Black-tufted marmoset, Callithrix penicillata
Wied's marmoset, Callithrix kuhlii
White-headed marmoset, Callithrix geoffroyi
Buffy-headed marmoset, Callithrix flaviceps
Buffy-tufted marmoset, Callithrix aurita
Genus Mico—Amazonian marmosets
Rio Acari marmoset, Mico acariensis
Silvery marmoset, Mico argentatus
White marmoset, Mico leucippe
Emilia's marmoset, Mico emiliae
Black-headed marmoset, Mico nigriceps
Marca's marmoset, Mico marcai
Black-tailed marmoset, Mico melanura
Santarem marmoset, Mico humeralifer
Maués marmoset, Mico mauesi
Munduruku marmoset, Mico munduruku
Gold-and-white marmoset, Mico chrysoleucos
Hershkovitz's marmoset, Mico intermedius
Satéré marmoset, Mico saterei
Rondon's marmoset, Mico rondoni
Genus Callibella—Roosmalens' dwarf marmoset
Roosmalens' dwarf marmoset, Callibella humilis
Genus Cebuella—Pygmy Marmoset
Pygmy marmoset, Cebuella pygmaea

Behavior
Marmosets are highly active, living in the upper canopy of forest trees, and feeding on insects, fruit, leaves, tack, sap, and gum. They have long lower incisors, which allow them to chew holes in tree trunks and branches to harvest the gum inside; some species are specialised feeders on gum.Marmosets live in family groups of three to 15, consisting of one or 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, polygyny, and polyandry. In most species, fraternal twins are usually born, but triplets are not unknown. Like other callitrichines, marmosets are characterized by a high degree of cooperative care of the young and some food sharing and tolerated theft. Adult males, females other than the mother, and older offspring participate in carrying infants. Father marmosets are an exceptionally attentive example of fathers within the animal kingdom, going as far as assisting their mates in giving birth, cleaning up afterbirth, and even biting the umbilical cords attaching their newborn offspring to their mothers. Most groups scent mark and defend the edges of their ranges, but  whether they are truly territorial is unclear, as group home ranges greatly overlap.
The favorite food of marmosets is carbohydrate-rich tree sap, which they reach by gnawing holes in trunks. Their territories are centered on the trees that they regularly exploit in this way. The smaller marmosets venture into the very top of forest canopies to hunt insects that are abundant there.

References
External links
Primate Info Net Callithrix Factsheets
Common Marmoset Care