In zoology, a graminivore (not to be confused with a granivore) is a herbivorous animal that feeds primarily on grass (specifically "true" grasses, plants of the family Poaceae). The word is derived from Latin graminis, meaning "grass", and vorare, meaning "to eat." Graminivory is a form of grazing. These herbivorous animals have digestive systems that are adapted to digest large amounts of cellulose, which is abundant in fibrous plant matter and more difficult to break down for many other animals. As such, they have specialized enzymes to aid in digestion and in some cases symbiotic bacteria that live in their digestive track and "assist" with the digestive process through fermentation as the matter travels through the intestines.