Spider monkeys are large in size. Adult monkeys grow to be almost two feet tall excluding the tail. They have a powerful tail that they use as an extra limb. Spider monkeys like to hang upside-down with all four limbs and the tail holding on to branches which makes them look like a spider and thus their name. They also have the ability to swing from branch to branch at a high speed. Their fur colour can be black, brown, golden, red or tan.