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Scientific classification e
Kingdom: Animalia
Phylum: Bryozoa
Class: Gymnolaemata
Order: Ctenostomata

The Ctenostomata are an order of bryozoans in the class Gymnolaemata. The great majority of ctenostome species are marine, although Paludicella inhabits freshwater.

Ropalonaria venosa, an etching trace fossil of a Late Ordovician ctenostome bryozoan on a strophomenid brachiopod valve; Cincinnatian of southeastern Indiana.[1]

They are distinguished from their close relatives, the cheilostomes, by their lack of a calcified exoskeleton. Instead, the exoskeleton is chitinous, gelatinous, or composed only of a soft membrane, and always lacks an operculum. Colonies of ctenostomes are often composed of elongated, branch-like stolons, although more compact forms also exist.


  1. ^ Pohowsky, R.A. (1978). "The boring ctenostomate bryozoa: taxonomy and paleobiology based on cavities in calcareous substrata". Bulletins of American Paleontology 73: 192p. 

Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 910. ISBN 0-03-056747-5.