Ctenidium (mollusc)

A live individual of Pleurobranchaea meckelii; the ctenidium is visible as a feather-like structure in this view of the right-hand side of the animal

A ctenidium is a respiratory organ or gill which is found in many molluscs. This structure exists in bivalves, cephalopods, polyplacophorans (chitons), and in aquatic gastropods such as freshwater snails and marine snails.[1] Certain molluscs, such as the bivalves,[2] possess paired ctenidia, but others, such as members of the Ampullariidae,[3] bear a single ctenidium.[4][5]

A ctenidium is shaped like a comb or a feather, with a central part from which many filaments or plate-like structures protrude, lined up in a row. Some aquatic gastropods possess a single row of filaments on their ctenidium, known as the monopectinate condition,[3] and others have a pair of filament rows, known as the bipectinate or aspidobranch condition.[6] The ctenidium hangs into the mantle cavity and increases the area available for gas exchange.[7] The word is Latinized but is derived from the Greek ktenidion which means "little comb", being a diminutive of the word kteis meaning comb.

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  Pair of large, grey gills visible inside the mantle cavity of a giant squid

References

1. Ruppert, Edward E.; Fox, Richard S. & Barnes, Robert D. (2004). Invertebrate Zoology: A Functional Evolutionary Approach. Thomson-Brooks/Cole. p. 286. ISBN 978-0-03-025982-1.
2. Morton, Brian (18 March 2024). "Bivalve: Food and feeding". Encyclopedia Britannica. Retrieved 11 November 2024.
3. Rodriguez, Cristian; Prieto, Guido I.; Vega, Israel A. & Castro-Vazquez, Alfredo (2019). "Functional and evolutionary perspectives on gill structures of an obligate air-breathing, aquatic snail". PeerJ. 7: e7342. doi:10.7717/peerj.7342. PMC 6679647. PMID 31396441.
4. Bunje, Paul (2003). "Lophotrochozoa: The Mollusca, Sea slugs, squid, snails, and scallops". UC Museum of Paleontology. University of California Museum of Paleontology. Retrieved 11 November 2024.
5. Nordsieck, Robert (2012). "Respiration and Circulation". The Living World of Molluscs. Support and scripting by Martina Eleveld. Retrieved 11 November 2024.
6. "aspidobranch". Macrobenthos of the North Sea - Mollusca. Naturalis Biodiversity Center. Retrieved 11 November 2024.
7. Respiratory system Archived 2020-08-09 at the Wayback Machine The apple snail. Retrieved 2012-04-20.