COMMON NAMES:

Marmosets and Tamarins

SCIENTIFIC NAMES:

There are two genera that fall under the category of marmosets, Callithrix and Cebuella. Between these two genera, there is a total of 8 species of marmosets. Below is a list of each species common name and its scientific name:

There are also two genera under the category of tamarins, Saguinus and Leontopithecus. Between these two genera, there is a total of 12 species of tamarins. Their common and scientific names are as follows:

PHYSICAL DESCRIPTION:

Marmosets and tamarins have fine, silky, multicolored and marked coats. Markings, including colors and patterns, are species specific, with each species having unique tufts, manes, and mustaches. This makes marmosets and tamarins the most diverse and colorful of the New World primates.

Sizes range from 7-7.5 in. with a 7.5 in. and a mass of 120-190 kg of the Pygmy marmoset, to 13-16 in. with a 10-15 in. tail and a mass of 630-710 kg of the Lion tamarin. These primates are "squirl-like" in size and stature and have claws on all digits, except the big toe, which has a nail. Their hind legs are especially useful for holding onto a limb while reaching for a piece of fruit or an insect. The claws provide a sure, steady anchor.

The tails of these primates are not prehensile, and is used in balancing while climbing, leaping, and reaching. They are considered quadrupeds, with grasping hands on all appendages. They are very agile creatures, crossing from tree to tree by running along branches at incredibly fast speeds.

Females have a simple uterus, while both sexes lack a rear inner cusp on the upper molars, suggesting that they are advanced primates which have evolved to a smaller size due largely to an insectivorous diet.

Marmosets and tamarins do have a variety of facial expressions, which help aid in communication, but not near the amount as many of their other primate cousins do. Their teeth are similar in arrangement to that of other primates, having the dental formula of , one more premolar and one less molar than most other primates. They are typical of New World monkeys in that their nose has a very wide septum, and forward-pointing nostrils. Their eyes are very human looking, and are usually brown in color.

GEOGRAPHY:

Marmosets and tamarins are found in the northern, central, east coastal, and Amazon regions of South America, including modern-day Brazil, Peru, Colombia, and Panama. Groups are found in both mountain and valley regions (but never of a very high altitude), in areas dense in tall trees.

HABITAT:

Jungles rich in tall, fruit-bearing trees are favorite living areas of tamarins and marmosets. This is largely due to their diet of various fruits, gums, flowers, insects, and saps. They have been known to also inhabit dryer, semi-deciduous forests. Each group claims an area of about 25-100 acres for themselves, roaming at least one-third of it daily.

Tall, old-growth trees are very important to these small primates since holes in very tall, old trees are the preferred areas for sleeping, offering the greatest protection from predators. They are primarily diurnal, fearing the night, seeking safety in the trees from predators.

DIET:

Tamarins and marmosets gain their nourishment primarily through fruits. This stapple is augmented by nectars, flowers, saps, gums, and small animals such as frogs, lizards, insects, and spiders. They have also been known to eat leaf buds, but not mature leaves.

In almost all species, it appears that each individuals size is effected by the abundance of food, as well as the type of food that it is able to feed upon from the time of intfantcy. This has been said about humans too, the better a child's nutrition, the better chances they have of reaching their full size potential.

Marmosets and tamarins are very clever in that they gouge trees so that the tree will produce saps and gums for them to feed upon. Although this is not the main ingredient of their diet, it is a favorite "treat," and an abundancy of gouges can be observed in the trees that are in areas that these small animals frequent.

A majority of the species of marmosets and tamarins spend between 25 and 30% of their time searching through leaves, trees, and brush for insects and other small prey. An interesting observation is that almost each species is highly adapted and dependent upon the edible resources found in their specific area. This is why you will never see more than one species of marmoset in a particular area, and rarely more than one species of tamarin in a specific area.

SOCIAL STRUCTURE:

Marmosets and tamarins are very social animals, and live in family groups ranging from 4 to 15 members. As a rule, each family is very territorial, and protects and keeps a range of 25 to 100 acres as theirs. The only exception to this is found in saddle-back and emperor tamarins, where sometimes families of either species will share certain areas with each other. Zoologists are still uncertain as to why this behavior happens, but it is clear that both groups watch out for one another by helping keep an eye pout for predators, and signaling the other group in times of danger.

These creatures are extremely active, and roam about one-third of their territory daily, traveling up to 1.2 miles in one day. Marmosets and tamarins protect their territories from each other by calling, chasing, displaying, and posturing. They are not violent creatures and rarely take any physical action against a tress-passer.

Territories are marked with scents produced by chest and suprapubic glands, recognized by that family. Scent appears to also be a way of communication other than just boundary marking. A member can leave a scent in an area frequented by other members, almost like a note, conveying an impression or "message" to the member that smells it. Facial expressions and chattering are primary ways of communication, as well as posturing and fur bristling. Although marmosets and tamarins do not have as wide a variety of facial expressions as many other primates, they still have more facial muscle control than most other animals.

As in almost every other type of primate, grooming plays a key element in the social structure of the group. Communal grooming is a very important part of family relations, especially between mothers and offspring and breeding pairs. Grooming is important to rid the skin and fur of parasites, dirt, and debris.

Sexuality plays little part in the social structure, with only one female able to breed per season. She may mate with more than one male, and almost always gives birth to non-identical twins. Breeding females usually change with each new breeding season.

Although sex is not a primary social element, infants and young are. The entire family unit help care for the young, as well as the mother during and soon after pregnancy. Even males will help carry the young for the first two weeks after birth, until the baby is mobile. Group members will often bring food to the youngsters, as well as the new mother, especially while she is pregnant.

REPRODUCTIVE STRATEGY:

Female marmosets and tamarins can produce up to 2 litters a year. Gestation lasts from 130 to 170 days, with birth weight as high as 19 to 25% of the mother's body weight

There are almost always non-identical twins born each time, which are entirely dependent upon the mother and family for the first two weeks, and can travel independently by two months.

Sexual maturity is reached between 12 and 18 months of age, with full growth being reached at about two years of age. The young are playful, often disrupting the family unit and being mischevious.

CURRENT CONDITIONS:

Unfortunately, many of the marmoset and tamarin species are either threatened or endangered due to deforestation. These small primates are very vulnerable to habitat destruction due to their limited and specialized diets.

Populations were drastically decimated during the 1970's when thousands were being exported legally for biomedical research, as well as pets and zoo exhibits. Today, thankfully, actions are being taken to preserve their natural habitat and increase their populations. Currently, only Bolivia, Panama, and French Guinea still permit their export.

REFERENCES:

Mammals: A Multimedia Encyclopedia, National Geographic Society, Washington D.C., 1990.

Rosen, S.I., Introduction to the Primates, Living in Fossil, 1974.

Buettner-Janusch, John, Evolutionary and Genetic Biology of Primates, Vol. II, 1964.

Schultz, Adolph H., The Life of Primates, 1969.

All the Worlds Animals-Primates, Torstar Books, 1984.

Eimerl, Sarel and DeVor, Irvin, The Primates, Time Life Nature Library, 1965.