High Quality Content by WIKIPEDIA articles! The spiny rats are a group of hystricognath rodents in the family Echimyidae. They are distributed from central Central America through much of South America. They were also found in the West Indies until the 1800s. Some authorities consider the nutria from southern and central South America to be a part of this family. In general form, most spiny rats resemble rats, although they are more closely related to guinea pigs and chinchillas. Most species have stiff pointed hairs, or spines, that allow for protection.