Different tamarin species vary considerably in appearance, ranging from nearly all black through mixtures of black, brown and white. Mustache-like facial hairs are typical for many species. Their body size ranges from 13 to 30 cm (5.1 to 11.8 in) (plus a 25-to-44 cm-long (9.8-to-17.3 in) tail) and they weigh from 220 to 900 grams (7.8 to 31.7 oz). Tamarins differ from marmosets primarily in having lower canine teeth that are clearly longer than the incisors. In captivity, tamarins can live for up to 18 years.
Tamarins are inhabitants of tropical rainforests and open forest areas. They are diurnal and arboreal, and run and jump quickly through the trees. Tamarins live together in groups of up to 40 members consisting of one or more families. More frequently, though, groups are composed of just three to nine members.
Gestation is typically 140 days, and births are normally twins. The adult males, subadults, and juveniles in the group assist with caring for the young, bringing them to their mother to nurse. After approximately one month the young begin to eat solid food, although they aren't fully weaned for another two to three months. They reach full maturity in their second year. Tamarins are almost exclusively polyandrous.
Cottontop tamarins (Saguinus oedipus) breed cooperatively in the wild. Cronin, Kurian, and Snowdon tested eight cottontop tamarins in a series of cooperative pulling experiments. Two monkeys were put on opposite sides of a transparent apparatus containing food. Only if both monkeys pulled a handle on their side of the apparatus towards themselves at the same time would food drop down for them to obtain. The results showed that tamarins pulled the handles at a lower rate when alone with the apparatus than when in the presence of a partner. Cronin, Kurian, and Snowdon concluded from this that cottontop tamarins have a good understanding of cooperation. They suggest that cottontop tamarins have developed cooperative behaviour as a cognitive adaptation.
While tamarins spend much of their day foraging, they must be on high alert for aerial and terrestrial predators. Due to their small size compared to other primates, they are an easy target for predatory birds, snakes, and mammals.
The first classification of Saguinus tamarins contained ten different species, further divided into 33 morphotypes based on facial pelage. A later classification into two clades was based on variations in dental measurements. The latest classification postulates fifteen species with no subspecies. A genetic review in 2016 revealed that the oldest species groups first began diverging 11–8 million years ago (considerably earlier than the divergence between Callithrix, Cebuella and Mico), leading the authors to recommend moving the nigricollis group to a separate genus, Leontocebus. Other authors argued that the mystax group of tamarins is distinct enough to be classified in the subgenus Tamarinus.
^Rylands AB, Mittermeier RA (2009). "The Diversity of the New World Primates (Platyrrhini): An Annotated Taxonomy". In Garber PA, Estrada A, Bicca-Marques JC, Heymann EW, Strier KB. South American Primates: Comparative Perspectives in the Study of Behavior, Ecology, and Conservation. Springer. pp. 21–54. ISBN978-0-387-78704-6.
^ abGarbino, Guilherme S.T.; Martins-Junior, Antonio M.G. (2018). "Phenotypic evolution in marmoset and tamarin monkeys (Cebidae, Callitrichinae) and a revised genus-level classification". Molecular Phylogenetics and Evolution. 118: 156–171. doi:10.1016/j.ympev.2017.10.002. PMID28989098.
^ abHershkovitz, Philip (1977). Living New World Monkeys (Platyrrhini) : With an Introduction to Primates (1st ed.). University of Chicago Press. ISBN9780226327884.
^Natori, M.; Hanihara, T. (1992). "Variations in dental measurements between Saguinus species and their systematic relationships". Folia Primatologica. 58 (2): 84–92. doi:10.1159/000156612. PMID1612537.
^Rylands, Anthony B.; Eckhard W. Heymann; Jessica Lynch Alfaro; Janet C. Buckner; Christian Roos; Christian Matauschek; Jean P. Boubli; Ricardo Sampaio; and Russell A. Mittermeier (2016). "Taxonomic Review of the New World Tamarins (Primates: Callitrichidae)". Zoological Journal of the Linnean Society. 177 (4): 1003–1028. doi:10.1111/zoj.12386.CS1 maint: Uses authors parameter (link)
^Gregorin, R.; De Vivo, M. (2013). "Revalidation of Saguinus ursula Hoffmannsegg (Primates: Cebidae: Callitrichinae)". Zootaxa. 3721 (2): 172–182. doi:10.11646/zootaxa.3721.2.4.