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A common marmoset with white ear tufts and a striped tail resting on a branch.
Photo: Raimond Spekking, CC BY-SA 4.0, via Wikimedia Commons

Common Marmoset

Callithrix jacchus

A tiny tree-sap-eating monkey of northeastern Brazil with white ear tufts, usually born as twins.

🐒 Monkeys
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About the Common Marmoset

Common marmosets live in the forests of northeastern Brazil, often along forest edges. An adult weighs only 300 to 360 grams, less than a pound. Marmosets feed mainly on tree sap, plus insects, spiders, fruit, flowers and nectar. They live in family groups of 2 to 13, and mothers usually give birth to twins.[1]

Quick facts

Scientific name
Callithrix jacchus[1]
Size
Body 12 to 15 cm long, with a 29.5 to 35 cm tail.[1]
Weight
300 to 360 grams (under 1 pound).[1]
Lifespan
About 10 years in the wild. 12 to 16 years in captivity.[1]
Diet
Mainly tree sap, plus insects, spiders, fruit, flowers and nectar.[1]
Habitat
Forest edges and coastal rainforest.[1]
Where it lives
Northeastern Brazil.[1]
Group life
Family groups of 2 to 13.[1]
Babies
Usually twins. Fathers and older siblings help care for them.[1]
Conservation status
Least Concern (IUCN Red List, assessed 2015).[2]

Fun facts

  • A marmoset's tail is about twice as long as its body.[1]
  • Common marmosets have white ear tufts and a white patch on the forehead.[1]
  • Marmoset twins can weigh up to 40 percent of their mother's weight.[1]
  • Tree sap is a marmoset's main food.[1]

Vocabulary

sap
The sticky liquid that flows inside trees.
ear tuft
A clump of long hair that sticks out from the ear.
twins
Two babies born at the same time to the same mother.
sibling
A brother or sister.
primate
A mammal with grasping hands and forward-facing eyes, like monkeys, apes and humans.

See it in person

Sources

  1. [1] Animal Diversity Web, University of Michigan Museum of Zoology. “Callithrix jacchus (common marmoset).” https://animaldiversity.org/accounts/Callithrix_jacchus/ (accessed 2026-10-02)
  2. [2] IUCN Red List of Threatened Species. “Callithrix jacchus (Common Marmoset).” https://www.iucnredlist.org/species/41518/191705043 (accessed 2026-10-02)

Facts last checked 2026-10-02.

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