The Oligohymenophorea are a large class of
ciliate
The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a differen ...
s. There is typically a ventral groove containing the mouth and distinct oral cilia, separate from those of the body. These include a paroral membrane to the right of the mouth and
membranelles, usually three in number, to its left. The
cytopharynx is inconspicuous and never forms the complex