Parasites occur among virtually all life forms on earth. Almost every plant or animal is subject to parasitism by one or more parasites. Parasitism occurs when the parasite plant or animal lives on or inside of the host plant or animal in order to feed on it. Heterotrophic nutrition is one form of parasitic nutrition. Autotrophic (self-nourishing) organisms synthesize their food either through photosynthesis, or in the case of some bacteria, by chemosynthesis. All animals and fungi and most bacteria feed themselves by some means of nutritional heterotrophy. In the case of animals, they are holozoic heterotrophs, that is, they eat solid particles. In the case of yeasts, molds, or most bacteria, the nutritional form is the saprophytic “eating” of decaying plant or animal matter. ...