Rodents have many special features. All rodents have one pair of upper and lower chisel-shaped incisor teeth that are covered with hard enamel on the front and a softer substance like bone on the back. As the rodent gnaws, the backs of the chisel-shaped teeth wear away faster to maintain a sharp edge. The incisors grow all of the time or continuously. If the rodent does not keep gnawing, the front incisors will grow right out of its mouth and prevent it from eating.

     Gnawing is not chewing. Gnawing means that the rodent nips off, or shaves off, layers of food or hard wood. When the food is inside its mouth, it chews the food into shreds. It does this with flatter teeth called molars, before swallowing the food. Some rodents have molars that grow all of the time much like the front teeth. Still others have powerful jaw muscles that let them chew in a special circular way that shreds hard fibrous foods better.

     Most rodents, but not all, have four toes on the front feet and five toes on the back feet. Most rodents are nocturnal (awake at night).

     Rodents, as a group, are very active and must eat a large amount of food. During the winter when food is scarce, some rodents hibernate. Others store food and wake from a deep sleep to eat from time to time. Small members of the rodent family give birth to many young. Rodents have lots of natural predators.