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mollusk
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Conchyliologie Tableau de la Classification des Coquilles Organizational levels and body diagrams of mollusks blue-ringed octopus
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The structure of snail shells explained
Representative mollusks. Bivalves have a shell with two halves. Filter feeders, they take in food and water through a tubular siphon. In the clam, a muscular foot is used for burrowing and creeping. The chitons, typically found adhering to rocks and shells, have shells divided into eight overlapping plates. Tusk shells, or scaphopods, are burrowing mollusks with a shell open at both ends; with the larger end buried in the sand, they feed on microorganisms captured by the tentacles. The whelks, like most gastropods (univalves), have a single shell, which is usually coiled; when threatened, the body can be pulled into the shell, which is closed by a plate (operculum). Cephalopods have a well-developed head and a foot divided into numerous tentacles. The two long tentacles of the squid are used to capture prey, and the short arms transfer food to the mouth. The nautilus is the only cephalopod that has retained an exterior shell; by regulating the amount of gas and fluid in the interior chambers, it can regulate its buoyancy.
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mollusk summary
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Sea otter (Enhydra lutris), also called great sea otter, rare, completely marine otter of the northern Pacific, usually found in kelp beds. Floats on back. Looks like sea otter laughing. saltwater otters
Animal Group Names
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The bearded vulture (Gypaetus barbatus) is seen in Switzerland on December 2024
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mollusk: References & Edit History

Additional Reading

An extensive and updated treatment of molluscan structure, function, and evolution is Karl M. Wilbur (ed.), The Mollusca, 12 vol. (1983–88). The phylum is outlined in Kenneth J. Boss, “Mollusca,” in Sybil P. Parker (ed.), Synopsis and Classification of Living Organisms, vol. 1 (1982), pp. 945–1166; while J.E. Morton, Molluscs, 5th ed. (1979), is a general discussion of their biology. Libbie Henrietta Hyman, The Invertebrates, vol. 6, Mollusca I (1967), contains information on the lower groups and a classic summary of gastropods. Other overviews include Alan Solem, The Shell Makers: Introducing Mollusks (1974); C.M. Yonge and T.E. Thompson, Living Marine Molluscs (1976); F.W. Harrison (ed.), Microscopic Anatomy of Invertebrates, vol. 5, Mollusca I (1994), and Microscopic Anatomy of Invertebrates, vol. 6, Mollusca II (1997); V. Fretter and A. Graham, British Prosobranch Molluscs, 2nd ed. (1994); R. Hanlon and J.B. Messenger, Cephalopod Behaviour (2005); C.M. Lalli and R.W. Gilmer, Pelagic Snails: The Biology of Holoplanktonic Gastropod Mollusks (1989); G. Vermeij, A Natural History of Shells (1995); and P.D. Ward, The Natural History of Nautilus (1987).

Article Contributors

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Article History

Type Description Contributor Date
Modified link of Web site: UH Pressbooks - Concepts of Zoology – Hawai'i Edition - Mollusks. Oct 30, 2026
Add new Web site: Frontiers - Frontiers in Ecology and Evolution - A brief global agenda for advancing the study of molluscs. Jan 31, 2026
Add new Web site: UH Pressbooks - Concepts of Zoology – Hawai'i Edition - Mollusks. Dec 19, 2025
Add new Web site: National Center for Biotechnology Information - PubMed Central - Diversity of benthic marine mollusks of the Strait of Magellan, Chile (Polyplacophora, Gastropoda, Bivalvia): a historical review of natural history. Dec 13, 2025
Add new Web site: PNAS - The physical basis of mollusk shell chiral coiling. Nov 08, 2025
Add new Web site: UEN Digital Press with Pressbooks - Biology and the Citizen - Mollusks and Annelids. Sep 16, 2025
Add new Web site: Montclair State University Digital Commons - The effects of nutrient enrichment and invasive mollusks on freshwater environments (PDF. Aug 29, 2025
Added cross-reference to mother-of-pearl. Jun 22, 2025
Add new Web site: Cell Press - Current Biology - Molluscs. Apr 16, 2025
Add new Web site: OpenEd CUNY - Superphylum Lophotrochozoa: Molluscs and Annelids. Dec 26, 2024
Add new Web site: Ocean Research Group - Mollusks: From Tiny Snails to Giant Squid! May 31, 2024
Add new Web site: MarineBio - Mollusks. Dec 29, 2023
Add new Web site: University of Hawaii - Exploring Our Fluid Earth - Phylum Mollusca. Oct 19, 2023
Add new Web site: University of Hawaii - Exploring Our Fluid Earth - Phylum Mollusca. Oct 19, 2023
Add new Web site: National Center for Biotechnology Information - PubMed Central - The evolution of molluscs. Mar 22, 2023
Add new Web site: A-Z Animals - Mollusk. Feb 15, 2023
Add new Web site: The Canadian Encyclopedia - Mollusc. Nov 25, 2022
Corrected display issue. Sep 08, 2022
Add new Web site: Biology LibreTexts - Phylum Mollusca. Apr 11, 2022
Media added. Apr 13, 2018
Add new Web site: Easy Science for Kids - Mollusk. Aug 08, 2016
Added video. Jan 08, 2016
Add new Web site: Buzzle.com - Mollusk. Feb 14, 2013
Add new Web site: University of California Museum of Paleontology - The Mollusca. Feb 14, 2013
Add new Web site: Marine Education Society of Australia - Life on Australian Seashores - Mollusc. Feb 14, 2013
Add new Web site: Earth-Life Web Productions - Mollusc. Feb 14, 2013
Add new Web site: Quatr.us - What are Mollusks? Feb 14, 2013
Add new Web site: Fact Monster - Science - Mollusca. Aug 17, 2010
Updated geologic time data. May 20, 2010
Article revised and updated. Nov 26, 2008
Added new Web site: University of Arizona - Phylum Mollusca. Jun 06, 2008
Added new Web site: How Stuff Works - Animals - Mollusk. May 28, 2008
Added new Web site: Miami-Dade County Public Schools - Marine Mollusks.
  • Gaurav Shukla
 Feb 20, 2007
Added new Web site: Animal Diversity Web - Phylum Mollusca. May 30, 2006
Article added to new online database. Jul 20, 1998
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