The anatomy of the guinea pig is a complex system of bones, organs and many other needed body structures. The guinea is a vertebrate, meaning is has a backbone as well as a skull and rib bones.
Guinea pigs have 20 teeth however you only see the first four. Their teeth serve a huge purpose for both guinea pigs in the wild as well as pets. The upper incisor is much like a beaver’s in that it continues to grow throughout the guinea’s life time. This is why a guinea pig shaves down their teeth by chewing on blocks of wood or the cage rails.
A guinea pig’s eye is much like that of a pig because theirs contains three eyelids in the front left corner of the eye.
Like humans, guinea pigs also have an iris and a pupil which adjusts to the amount of light it allows in.