(class Gymnolaemata, order Cheilostomata)
Suborder of cheilostome bryozoans in which the tentacles are protruded and withdrawn by means of a hydrostatic organ (the compensation sac). The operculum is hinged in such a way that it controls the flow of water into the interior. The suborder occurs from the Cretaceous to the present.
Subjects: Zoology and Animal Sciences.