Guinea pig is the common name for the Cavy.  Cavy is short for the species name Cavia Porcellus.  Under the family name of Caviidae, guinea pigs are described as South American rodents with no visible tail, a single pair of mammae, four toes on each front foot, and three toes on each back foot.  The Guinea pig neither comes from Guinea nor is a pig.  The most accepted explanation for the name is that the animals grunt and squeal like a pig and were sold by British sailors in the 1600's for a guinea, an old English coin.  Guinea Pigs weigh from 2 to 4 pounds and with good care can live 8 to 10 years. Guinea pigs are herbivorous, meaning they eat only grasses, vegetables and fruit.  They are sociable animals so it is best they do not live alone. They do very well in pairs and trios.