Spider Monkeys are semi-brachiators. They use their long arms and tail to swing through the trees. The hand is held in a hook grip while swinging. Group size varies, but there can be troops containing up to 100 individuals. There are more males than females in the groups.
Females are responsible for raising the young.
Tamarins Tamarins live in tropical rain forests and are thought to occupy the higher levels of the forest canopy on small branches. They eat a wide variety of foods, including insects, fruits, and small lizards. Tamarins often give birth to twins which is unusual for primates. There is one breeding female in each group. The groups often contain three members.