Spider Monkey at the Belize Zoo, the guide explained to us that this type of monkeys are mostly found living in the upper canopy, almost never coming near the ground. The spider monkey is considered to be a primitive new world monkey, which means they originated in the North or South America. They have less complex brain, unopposable thumbs, wide apart nostrils, feet with big toes and small heads. They have slender bodies (weigh about 20 pounds), hands and limbs and depend highly on their keen binocular vision.