Cyclostomatida

Mesonea radians

Cyclostomata (or Tubuliporata ) is the only extant order of the class Stenolaemata of bryozoans ( Bryozoa or Ectoprocta ). They appeared for the first time in the Ordovician and were, with about 175 species, particularly widespread in the Cretaceous period.

The name comes from its structure, which is not, as in the Cheilostomata box - but tubular with a circular opening for the crown of tentacles. Zooids individual pores can communicate with one another in the tube wall.

Some species

Crisia eburnea is a cosmopolitan species with up to 3 cm large, shrub -like off-white colonies. The type occurs mostly at depths of up to 300 m, but is also found in brackish water or estuaries.

Other genera are Crisella, Tubulipora and occurring in the North Sea Lichenopora. The latter two species form plate-like colonies, whereas the colonies of Crisella are more tree-like.