Order PERITRICHIDA Stein, 1859

Syns.:

Cyclohymenophora, Dexiotricha, Peritrichasina, Peritrichia, Peritrichidea, Peritrichorida, Stomatoda

With characteristics of subclass (above).

Sedentary or sessile (adults), commonly stalked (or with inconspicuous adhesive disc), with a few species secondarily mobile; many produce arboroid colonies; some entire groups loricate; mucocysts and pellicular pores universal; adults generally filter-feeding bactivores (larval stage mouthless); widely ranging habitats (fresh-water, brackish, marine), with animate substrata involving metazoa from many phyla (major exception: echinoderms); a few species live as endozoic forms.

Suborder (1) Sessilina Kahl, 1933

Mobile forms, conical, cylindrical, or goblet-shaped, sometimes discoidal (orally-aborally flattened); dominant feature the aboral (basal) disc, a holdfast organelle of considerable complexity (denticulate ring, radiating myonemes, etc.); trochal band permanently ciliated; stalkless with scopula generally vestigial (though producing cilia in some forms); all species associated with some other organism as "host", often fresh-water or marine invertebrates (on integument or gills), but other groups (ciliates, amphibians, especially fishes), and other locations (digestive and urogenital tracts) may also be involved; fish-gill forms pathogenic in heavy populations.

Suborder (2) Mobilina Kahl, 1933