One of the classes of Protozoa, including a large number of species, all of minute size. Formerly, the term was applied to any microbe found in infusions of decaying organic material, but the term is now applied more specifically to one of the classes of the phylum Ciliophora, of ciliated protozoans.
Microscopic or minute animal life which commonly occurs in water containing decaying organic matter. Includes paramecia, euglena, desmids, rotifers and others. Cultivated as food for Fry and small fishes.