guinea pigs teeth gnawing & chewing
Like all the typical rodents Guinea Pigs have chisel-like incisor teeth, which continue to grow through its entire life. When Guinea Pigs gnaw, there is a forward and backwards movement of the lower incisors which bite against the upper pair. While they do this the grinding cheek teeth do not meet one another and the back of the mouth can be closed by pulling in the cheeks behind the incisors. This mechanism allows gnawing to proceed for some time without swallowing gnawed material and saves wear on the molars. When the guinea pig decides to change from gnawing to chewing, the lower jaw moves backwards, one set incisors fits neatly behind the other, and the molars come into contact to begin the grinding process prior to swallowing. All this fancy mouth-work is controlled by a complicated set of special muscles.