Grazing - Non-grass Grazing

Non-grass Grazing

Although the word grazing is typically associated with mammals feeding on grasslands, or more specifically livestock in a pasture, ecologists sometimes use the word by extension 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 varies even more than this, 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 will 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.

An example of a grazer that may seem counterintuitive is a mosquito, which is not a parasite in that it does not form any lasting association with its prey, and is not a true predator in that it does not kill them by this process (although they can act as a vector for fatal diseases such as malaria). In this sense it is the antithesis of parasitoidism, in which an organism (typically the larval stage of a wasp) feeds on another by eating it from within. In that case, the prey is inevitably killed by predation, and has an intimate association with its predator, such that its premature death would also see the parasitoid die as well.