Guinea pigs are very social mammals that communicate using chirps, burbles, or squeaks to express emotion. In response to being startled, they have been spotted motionless or frantically scurrying. The staple food of their diet is grass. Their hobby is swimming: guinea pigs make very good swimmers. On average, these mammals can live for five years, measure nine inches long, and weigh two pounds. Internationally, guinea pigs are studied in medical research and eaten as a traditional food source.