The guinea pig or cavy is a native of the mountains and grasslands South America. Their wild relatives are found in Peru. Their closest relatives (other than wild cavies) are porcupines, agoutis, chinchillas and animals such as the coypu.
All rodents are collectively part of the group Rodentia. This order is divided into sub-orders. Guinea pigs belong to Histricomorpha.
Guinea pigs have teeth designed to gnaw which grow continously. They have two pairs of incisors, one pair of premolars and three pairs of molars. There is a gap, diastema, between the incisors and premolars instead of canine teeth. Their average weight ranges from 2.5lbs to 3lbs for a sow and 3lbs to 3.5lbs for a boar.