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gastropod

gastropod, member of the class Gastropoda, the largest and most successful class of mollusks (phylum Mollusca), containing over 35,000 living species and 15,000 fossil forms. The shell of gastropods is of one piece (called univalve) and usually coiled or spiraled as in snails, periwinkles, conches, whelks, limpets, and abalones; however, in some forms, as in slugs and sea slugs, it is reduced or completely absent. There is usually a definite head, bearing one or two sensory tentacles and a mouth that is often equipped with a rasplike tongue called a radula. The lower surface of the animal is modified into a large, flattened foot, used by bottom-dwelling forms for creeping about. The foot and other soft parts of the body can usually be completely withdrawn into the shell and the opening covered by a permanent plate called the operculum. Ancient gastropods were probably bilaterally symmetrical, but living species undergo a process known as torsion in which most of the body behind the head rotates 180° so that the anal and urinary openings are relocated behind the head, and the digestive tract and nervous system become U-shaped. Most gastropod species are marine but many groups, notably the pulmonate (lung-bearing) snails, have successfully invaded freshwater and moist terrestrial habitats.

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"gastropod." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

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Gastropoda

Gastropoda (gastropods; phylum Mollusca) A class of molluscs, of asymmetrical form, including snails and slugs, which have a true head, an unsegmented body, and a broad, flat foot. When present, the shell is in one piece and spirally coiled, at least in young stages. The mantle cavity and visceral mass have undergone torsion, at least in the developmental stage. There is usually a well-developed radula. Gastropods inhabit a wide range of aquatic and terrestrial environments, and range from the Cambrian to the present. Fossils of coiled gastropod shells are common in marine rocks, especially those of the Cenozoic. All fossil gastropods and most modern ones have a coiled shell, which is all that remains for the identification of fossil forms. The identification of modern species is based largely on soft body parts.

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"Gastropoda." A Dictionary of Zoology. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

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"Gastropoda." A Dictionary of Zoology. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/gastropoda-0

Gastropoda

Gastropoda (gastropod; phylum Mollusca) The class of Mollusca that includes snails and slugs. They have a true head, an unsegmented body, and a broad, flat foot. They appear in the Cambrian and occur in sedimentary rocks of all ages, occupying a range of aquatic and terrestrial environments. The majority of modern gastropods and all the fossil forms possess a coiled shell, which is all that is left to the palaeontologist for determining identification. The classification of living forms is based largely upon soft parts, so that similarly shaped shells developed by unrelated groups cause problems of nomenclature.

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"Gastropoda." A Dictionary of Earth Sciences. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

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"Gastropoda." A Dictionary of Earth Sciences. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/gastropoda

gastropod

gastropod Member of the Gastropoda class of molluscs, which includes the snail, slug, whelk, limpet, abalone and sea slug. Many possess a single spiral shell produced by chemical precipitation from the mantle. Many types of gastropod live immersed in seawater, breathing through gills. Some freshwater snails, however, breathe through lungs and surface periodically for air. Sea slugs are entirely without shells.

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"gastropod." World Encyclopedia. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

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"gastropod." World Encyclopedia. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/gastropod

Gastropoda

Gastropoda A class of molluscs that includes the snails, whelks, limpets, land and sea slugs, and conches. Molluscs have a well-developed head with tentacles, a large flattened foot, and a coiled twisted shell. They occupy marine, freshwater, and terrestrial habitats; in the terrestrial and some freshwater gastropods the mantle cavity acts as a lung instead of enclosing gills.

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"Gastropoda." A Dictionary of Biology. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

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"Gastropoda." A Dictionary of Biology. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/gastropoda-1

gastropod

gas·tro·pod / ˈgastrəˌpäd/ • n. any mollusk of the class Gastropoda, often with a spiral shell, that moves by means of a large muscular foot, including snails, slugs, and whelks.

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"gastropod." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

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"gastropod." The Oxford Pocket Dictionary of Current English. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/gastropod-0

gastropods

gastropods See GASTROPODA.

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"gastropods." A Dictionary of Zoology. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

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"gastropods." A Dictionary of Zoology. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/gastropods

gastropod

gastropodbod, clod, cod, god, hod, mod, nod, od, odd, plod, pod, prod, quad, quod, rod, scrod, shod, sod, squad, tod, Todd, trod, wad •demigod • amphipod • unipod •tripod • isopod • myriapod • decapod •cephalopod • monopod • macropod •gastropod • arthropod • sauropod •ramrod • Nimrod • hotrod • pushrod •goldenrod • Novgorod • slipshod •roughshod • eisteddfod • tightwad

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"gastropod." Oxford Dictionary of Rhymes. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

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"gastropod." Oxford Dictionary of Rhymes. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/gastropod