The spider monkey's most striking feature is its long tail, which is longer than its body. This muscular appendage is covered in hair and is strong enough to support the monkey's entire body as it swings from tree to tree. The spider monkey also has long arms and legs, which it uses to hang from branches and to grab food.
Spider monkeys typically reach lengths of 33-63.5 cm (13-25 in), and weigh 5.5-10 kg (12-22 lb). The largest species of spider monkey is the Ateles belzebuth, which can grow to lengths of over 2 meters (6 feet) and weigh up to 11 kilograms (24 pounds).