grazing on
seagrass Many small selective herbivores follow larger grazers which skim off the highest, tough growth of grasses, exposing tender shoots. For terrestrial animals, grazing is normally distinguished from
browsing in that grazing is eating grass or
forbs, whereas browsing is eating woody twigs and
leaves from
trees and
shrubs. Grazing differs from
predation because the organism being grazed upon may not be killed. It differs from
parasitism because the two organisms
live together in a constant state of physical externality (i.e., low intimacy).
Water animals that feed by rasping algae and other micro-organisms from stones are called
grazers–scrapers.
Graminivory 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.
Cecotrophy is one of several
herbivores that practice
cecotrophy. For
lagomorphs (
rabbits,
hares,
pikas), easily digestible food is processed in the gastrointestinal tract & expelled as regular feces. But to get nutrients out of hard-to-digest fiber, lagomorphs ferment fiber in the cecum (in the GI tract) and then expel the contents as
cecotropes, which are reingested (
cecotrophy). The cecotropes are then absorbed in the small intestine to utilize the nutrients. This process is different from cows chewing their cud but with similar results.
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, feeding on the leaves of one species and 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; hence, it chews food by grinding back-and-forth rather than side-to-side. Like lagomorphs, capybara create, expel & eat
cecotropes (
cecotrophy) to get more nutrition 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. 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".
Non-grass grazing Although grazing is typically associated with
mammals feeding on
grasslands,
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. Use of the term "grazing" varies further; for example, a
marine biologist may describe herbivorous
sea urchins that feed on kelp as
grazers, even when they kill the organism by cutting the plant at the base.
Malacologists sometimes apply the word to aquatic snails that feed by consuming the microscopic film of
algae,
diatoms and detritus—a
biofilm—that covers the
substrate and other surfaces underwater. In marine
ecosystems, grazing by
mesograzers such as some
crustaceans maintains habitat structure by preventing algal overgrowth, especially in
coral reefs. ==Benefits==