Many small selective herbivores follow larger grazers, who skim off the highest, tough growth of plants, exposing tender shoots. For terrestrial animals, grazing is normally distinguished from browsing in that grazing is eating grass or forbs, and browsing is eating woody twigs and leaves from trees and shrubs. Grazing differs from true predation because the organism being grazed upon is not generally killed. Grazing differs from parasitism as the two organisms live together in a constant state of physical externality (i.e. low intimacy).[page needed] Water animals that feed for example on algae found on stones are called grazers-scrapers. Grazers-scrapers feed also on microorganisms and dead organic matter on various substrates.
Grazing is a method of feeding in which a herbivore feeds on plants such as grasses, or other multicellular organisms such as algae.
Graminivory is a form of grazing involving feeding primarily on grass (specifically "true" grasses in the Poaceae). Horses, cattle, capybara, hippopotamuses, grasshoppers, geese, and giant pandas are graminivores. Giant pandas (Ailuropoda melanoleuca) are obligate bamboo grazers, 99% of their diet consisting of sub-alpine bamboo species.
Rabbits are herbivores that feed by grazing on grass, forbs, and leafy weeds. They graze heavily and rapidly for about the first half-hour of a grazing period (usually in the late afternoon), followed by about half an hour of more selective feeding. If the environment is relatively non-threatening, the rabbit remains outdoors for many hours, grazing at intervals. Their diet contains large amounts of cellulose, which is hard to digest. Rabbits solve this problem by using a form of hindgut fermentation. They pass two distinct types of feces: hard droppings and soft black viscous pellets, the latter of which are known as caecotrophs and are immediately eaten (coprophagy). Rabbits reingest their own droppings (rather than chewing the cud as do cows and many other grazer) to digest their food further and extract sufficient nutrients.
Capybara (Hydrochoerus hydrochaeris) are herbivores that graze mainly on grasses and aquatic plants, as well as fruit and tree bark. As with other grazers, they can be very selective and feed on the leaves of one species, disregarding other species surrounding it. They eat a greater variety of plants during the dry season, as fewer plants are available. While they eat grass during the wet season, they have to switch to more abundant reeds during the dry season. The capybara's jaw hinge is not perpendicular and therefore they chew food by grinding back-and-forth rather than side-to-side. Capybara are coprophagous, as a source of bacterial gut flora, to help digest the cellulose in the grass that forms their normal diet, and to extract the maximum protein and vitamins from their food. They may also regurgitate food to masticate again, similar to cud-chewing by a cow. As with other rodents, the front teeth of capybara grow continually to compensate for the constant wear from eating grasses; their cheek teeth also grow continuously.
The hippopotamus is a large, semi-aquatic, mammal inhabiting rivers, lakes and mangrove swamps. During the day, they remain cool by staying in the water or mud; reproduction and childbirth both occur in water. They emerge at dusk to graze on grasses. While hippopotamuses rest near each other in the water, grazing is a solitary activity. Their incisors can be as long as 40 cm and the canines up to 50 cm, however, the canines and incisors are used for combat and play no role in feeding. Hippos rely on their broad, horny lips to grasp and pull grasses which are then ground by the molars. The hippo is considered to be a pseudoruminant, it has a complex three- or four-chambered stomach but does not "chew cud".
Although grazing is typically associated with mammals feeding on grasslands, or more specifically livestock in a pasture, ecologists sometimes use the word in a broader sense, to include any organism that feeds on any other species without ending the life of the prey organism.