(class Ciliatea, subclass Spirotrichia)
An order of ciliate Protozoa in which the body cilia are either uniformly arranged or absent. The cell body is often large (e.g. in Spirostomum it is up to 3 mm long). There are eight families, and many genera, found in freshwater and marine habitats, and as commensals (see commensalism) in the intestines of animals.
Subjects: Zoology and Animal Sciences.