Sloth

Sloths are mammals native to South and Central America. They live in rainforests, and feed exclusively on leaves and fruit.

The sloth in Zoo seems to be a Linnaeus' two-toed sloth - a species which can be found in Northern South America. In the Zoo universe, this species suffers from a "phase two mutation", meaning that it's needed in order to make a cure for the other animals. The sloth is also capable of causing earthquakes when feeling treathened.