There is a family of mammals called ‘sloth’ found in tropical South America, the members of which spend most of their lives in upside down position. They move about the tree tops in very slow motion usually at night. They use the hooked claws of both their toes and fingers to move upside down and spend most of their lives in this peculiar position. The sloths can even go to sleep in this position. In sleep, their muscles become fixed and would not relax until the animal wakens and purposely does so. The sloths eat, mate and even give birth to their young in this position.
There are two interesting characteristics related to this strange habit of sloths. The first is its ability to turn its head almost right round to compensate for its reverse position. The second relates to its hair that lies in the opposite direction to that of most of the other animals. The sloth’s hair runs from its belly round to its back, and this ensures that heavy tropical showers run straight off.
The sloth hardly has any tail. Its nose is blunt and the peglike teeth are well-developed. The animal is hardly visible in trees because green algae cover the animal’s hair, providing camouflage. It feeds on leaves, buds and fresh twigs of trees.
There are two main species of sloths. The unau or two-toed sloth which has two toes on the front and the ai, or three-toed sloth which has three toes on the front feet. In prehistoric times there were huge giant sloths that were about 6 metres (20 ft.) tall.