Guinea pigs have a total of 258 bones in their body. There are 34 bones in the spinal cord, 43 in each front leg, 36 in each back leg and for you mathematicians the rest of the bones make up the skull, ribs and breastbone. Despite the number of bones in their legs, they do not jump or land very well, and a fall is likely to result in them breaking a leg, so they must always be held and carried very carefully.
There are actually seven tail bones, but they are fused so closely to the bottom (pelvis) there is no recognisable tail on these little creatures.
The eyes are large and placed on either side of the head. They have a wide field of vision so that they can detect predators coming from above or from any angle on the ground. They are unable to see right in front of their noses though! Their sight is not particularly good, although they are believed to see different colours and are able to see moving objects.
Their eyes, like humans come in a variety of colours - black, brown, ruby and red. A healthy eye will appear clear and bright.
Guinea pigs have a very well developed sense of smell, and they also have whiskers around their nose, eyes and mouth which are very sensitive to touch. The senses of smell and touch are very important when choosing food items (their favourite occupation is eating!) as due to their eye placement, they are unable to see what they eat.
The guinea pig has a very good sense of hearing, and can hear sound frequencies that are inaudible to the human ear. They can certainly hear you open the fridge door from their home in the garden!