The order is deveded into three suborders accordingot arrangement of jaw muscles. In the spuirrel-like rodents the masseter is used only to pull the lower jaw upward. In the cave-like rodents the deep masseter contribures to latitudian and longitudinal movement of the lower jaw. Both the deep and lateral masseter are trust forward in the mouse-like rodents. This produces the most effective gnawing of all the rodent suborders.
Most rodents eat a wide range of plant material as well as invertebrates.
A few are specialized carnivores. To facilitate the digestion of cellulose rodents have a reletively large cecum where endocybiotic bacteria break down cellulose. This is the same process as in the Lagomorphs . Rodents are quite intellegent and can master simple tasks when conditioned. Their sense of smell and heearing are well developed.