Spider monkeys have long, thin arms with hook like hands that allow them to swing through the trees. They do not have opposable thumbs(对生拇指).

    The brown-headed spider monkey has a prehensile(缠绕性的)tail, which means it can grasp and can be used like a fifth leg to grab trees. During the day, the spider monkey searches for fruits, which make up the main part of its diet. They will also eat flowers, seeds, leaves, and small insects during the dry season when fruits aren't available. They spend most of the daylight hours climbing and swinging through the high branches of trees.

    The brown-headed spider monkey lives in a large community of about 20 to 100 male and female monkeys. They split into smaller groups for feeding. Females usually give birth to only a single baby each year or two. Young monkeys are carried on their mothers' stomachs until about 16 weeks old. Then they are strong enough to ride on their mothers' backs. All brown-headed spider monkey babies are born with a pink face and ears.

    Spider monkeys hug each other and wrap their tails around each other. They are very intelligent and have strong memories. They were named spider monkeys because they look like spiders as they hang upside down from their tails with arms and legs swinging. Their genus (属)name is Ateles, which means “imperfect”. This refers to the fact that they don't have thumbs.

    Hunting the brown-headed spider monkey is nowbarredin Ecuador, a country in northwestern South America, but humans have killed them for their meat for hundreds of years.