Agoutis resemble large Guinea pigs with large legs. With their slender shoulders and head, and their more muscular hindquarters, they are well adapted for life in the jungle.

Their teeth are so sharp that they are able crack open the pods of Brazil nuts. Because of their habit of burying any uneaten seeds, Agoutis are responsible for most of the dispersal of Brazil nut trees. Any decline in the population of Agoutis leads to a decline in Brazil nut trees.