In the bryozoan order Cheilostomatida, the operculum is a calcareous or chitinous lid-like structure that protects the opening through which the polypide protrudes.
Many species have modified the operculum in specialized zooids (avicularia) to form a range of mandibles (probably for defense) or hair-like setae (probably for cleaning, or in some unattached species, such as Selenaria, for locomotion).
The cyclostome family Eleidae also convergently evolved an opercular structure during the Early Cretaceous to Paleocene.
References
- ^ Cook, P.L. & Chimonides, P.J. 1987. Recent and fossil Lunulitidae (Bryozoa, Cheilostomata), 7. Selenaria maculata (Busk) and allied species from Australasia. Journal of Natural Historia 21: 933-966
- ^ Taylor, P.D. 1994. Systematics of the melicerititid cyclostome bryozoans; introduction and the genera Elea, Semielea and Repromultelea. Bulletin of the Natural history Museum, Geology Series 50:1-103
