The sloth is a mammal that lives in the jungles of South America.

Their principal characteristic is that they move very slowly and they sleep more than 16 hours a day.

They are adapted to the environment with some physical features:

–       As they don’t obtain enough energy from the leaves they eat they accumulate solar energy. In the day their body reaches 35 degrees centigrade and at night it keeps at 25 degrees.

–       Their hairs are insulated so water doesn’t wet them.

–       They have very long claws (5-8cm) to climb trees easier and not to fall n the ground where jaguars could trap them because they move very slowly.

–       They have algae growing in their hair that make them green to camouflage from predators.

–       Thanks to their neck they could turn the head until 270º so they could see without moving very much.

–       Their forelegs have double length than the others because when they hang they grab with them.

–       Their outer hairs grow in a direction opposite form that of mammals, from the belly to the back because they are all day hanged so the rain water doesn’t wet them and don’t lose much hot.

And they are so famous because of their films 🙂


Firstly every sloth had the hairs growing as in all mammals, from the back to the belly, but as they were all days hanged in the branches, when it was raining they lost their heat because the became wet, as the water could enter the layer of hairs. Sloth doesn’t take enough energy from the leaves they eat so they sunbathe to warm their bodies without wasting energy. When the sloths lost their heat because of their hairs, they had to pass more time sunbathing and more of them were caught by eagles.

Then some of them started having an adaptation, theirs hairs grew in the opposite direction: from the belly to the back and then they didn’t lose so much heat and didn’t have to sunbathe too, so less of them died in the struggle of existence, and as only the fittest survive, the number of “new” sloths increase.

They started reproducing and as that characteristic was an advantageous one the traits passed to their descendants and it became a variation that made sloths better to survive.