Common Marmoset (Callithrix (Callithrix) jacchus) is a New World monkey. It originally seemed to only live on the northeast coast of Brazil. It was recently found also in southeast Brazil.
The fur of the common marmoset is grey. The most distinguishing characteristic is the white, tufts of hair that surround the ears. This lends it another common name, the Cotton Eared Marmoset. A white mark is on the forehead and the face is hairless. The long tail is grey-white. Common Marmoset adult size ranges from 5.51 to 46.46 in (14 to 18 cm) and they weigh approximately 14.11 oz (400 g).
Common Marmosets are diurnal. Their habitat ranges from the edge of forests into the deep forests, but they also appear in fields. They can run swiftly along the branches of trees and are also excellent jumpers.
Common Marmosets live together in family groups of four to 15 animals, usually mated adults and their offspring. The groups have a strict ranking, ordered by the dominance and aggressive behavior of the group leader.
The diet of the Common Marmoset consists of insects, spiders, small vertebrates, bird eggs and tree sap.
Common Marmosets have variable mating systems. All adults share in the care of the young. After an approximately 150-day gestation, the female typically gives birth to twins. Sometimes up to four offspring have been observed in captive settings (larger litters suffer higher mortality rates). Compared to adults, the young animals are very large. Newborn twins together are 20 percent to 27 percent of the body weight of the mother. It is assumed that the cooperative care of young helps counter some of the high costs of raising twin offspring. Males can mate after about one year. The females aren’t fully mature until about 20 to 24 months.
The life expectancy of the Common Marmosets in the wild is about 10 years, although some living in captivity have lived to 16 years.