views updated

Hymenostomatida (subphylum Ciliophora, class Ciliatea) An order of ciliate protozoa in which the mouth region is subterminal and located on the ventral surface of the cell. The arrangement of cilia in the mouth region is complex. Beating of these cilia causes water currents to direct food toward the mouth. There are three suborders. Most species are free-living in freshwater habitats, a few are parasitic.