any of five species of densely furred South American primates found in rainforests of the western Amazon River basin. Woolly monkeys average 40-60 cm (16-24 inches) in length, excluding the thick and somewhat longer prehensile tail. Females weigh 7 kg (15.5 pounds) on average, males a little more. The common, or Humboldt's, woolly monkeys (Lagothrix lagotricha and related species) have short fur that, depending on the species, is tan, gray, reddish, or black; some have darker heads. The head itself is large and round, with a bare black or brown face. Their bodies are thick with sturdy limbs, and their protruding bellies have given them the Portuguese name barrigudo, or "big belly."
Learn more about woolly monkey with a free trial on Britannica.com.