stenolaemate, any member of the class Stenolaemata, a group of colonial marine animals within the invertebrate phylum Bryozoa (moss animals). About 900 species of stenolaemates have been described. Only one of the four orders that make up the class, the Cyclostomata, is represented by living species; all members of the other three orders (Cystoporata, Trepostomata, and Cryptostomata) are now extinct. The stenolaemates are the oldest of all the bryozoans and date from the Early Ordovician Epoch (505 to 478 million years ago) on. The individuals (zooids) that make up a stenolaemate colony have narrow, cylindrical, sometimes very elongated tubes with calcified walls.

Crisia eburnea, found in tide pools on both coasts of North America, grows on algae and seaweed and forms white bushy tufts about 1.25 to 2.5 cm (0.5 to 1 inch) high.

This article was most recently revised and updated by John P. Rafferty.
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Cheilostomata, major group of calcified bryozoans (small, colonial, aquatic invertebrate animals) that first appeared during the Jurassic period (200 to 146 million years ago). Individual members of the cheilostome colony are small (usually less than 1 mm [0.04 inch]) and protected by a calcareous or chitinous covering that may be closed by a lidlike structure, an operculum. The cheilostomes are exclusively marine animals, and the colony frequently has an attractive, plantlike appearance. The cheilostomes are the most abundant and varied of modern bryozoans; there are about 2,800 described species.

This article was most recently revised and updated by Amy Tikkanen.
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