Definition of mollusca
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Mollusca (n. pl.) One of the grand divisions of the animal kingdom, including the classes Cephalopoda, Gastropoda, PteropodaScaphopoda, and Lamellibranchiata, or Conchifera. These animals have an unsegmented bilateral body, with most of the organs and parts paired, but not repeated longitudinally. Most of them develop a mantle, which incloses either a branchial or a pulmonary cavity. They are generally more or less covered and protected by a calcareous shell, which may be univalve, bivalve, or m
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Scutibranchiata ::
Scutibranchiata (n. pl.) An order of gastropod Mollusca having a heart with two auricles and one ventricle. The shell may be either spiral or shieldlike.
Conchifera ::
Conchifera (n. pl.) That class of Mollusca which includes the bivalve shells; the Lamellibranchiata. See Mollusca.
Mollusca ::
Mollusca (n. pl.) One of the grand divisions of the animal kingdom, including the classes Cephalopoda, Gastropoda, PteropodaScaphopoda, and Lamellibranchiata, or Conchifera. These animals have an unsegmented bilateral body, with most of the organs and parts paired, but not repeated longitudinally. Most of them develop a mantle, which incloses either a branchial or a pulmonary cavity. They are generally more or less covered and protected by a calcareous shell, which may be univalve, bivalve, or m
Opisthobranchiata ::
Opisthobranchiata (n. pl.) A division of gastropod Mollusca, in which the breathing organs are usually situated behind the heart. It includes the tectibranchs and nudibranchs..
Streptothrix ::
Streptoneura (n. pl.) An extensive division of gastropod Mollusca in which the loop or visceral nerves is twisted, and the sexes separate. It is nearly to equivalent to Prosobranchiata..
Tectibranchiata ::
Tectibranchiata (n. pl.) An order, or suborder, of gastropod Mollusca in which the gills are usually situated on one side of the back, and protected by a fold of the mantle. When there is a shell, it is usually thin and delicate and often rudimentary. The aplysias and the bubble shells are examples..
Ceratobranchia ::
Ceratobranchia (n. pl.) A group of nudibranchiate Mollusca having on the back papilliform or branched organs serving as gills.
Osphradium ::
Osphradium (n.) The olfactory organ of some Mollusca. It is connected with the organ of respiration.
Acephala ::
Acephala (n. pl.) That division of the Mollusca which includes the bivalve shells, like the clams and oysters; -- so called because they have no evident head. Formerly the group included the Tunicata, Brachiopoda, and sometimes the Bryozoa. See Mollusca..
Bojanus Organ ::
Bojanus organ () A glandular organ of bivalve mollusca, serving in part as a kidney..
Gastropoda ::
Gastropoda (n. pl.) One of the classes of Mollusca, of great extent. It includes most of the marine spiral shells, and the land and fresh-water snails. They generally creep by means of a flat, muscular disk, or foot, on the ventral side of the body. The head usually bears one or two pairs of tentacles. See Mollusca..
Cambrian ::
Cambrian (a.) Of or pertaining to the lowest subdivision of the rocks of the Silurian or Molluscan age; -- sometimes described as inferior to the Silurian. It is named from its development in Cambria or Wales. See the Diagram under Geology.
Conchology ::
Conchology (n.) The science of Mollusca, and of the shells which they form; malacology..
Bivalve ::
Bivalve (n.) A mollusk having a shell consisting of two lateral plates or valves joined together by an elastic ligament at the hinge, which is usually strengthened by prominences called teeth. The shell is closed by the contraction of two transverse muscles attached to the inner surface, as in the clam, -- or by one, as in the oyster. See Mollusca..
Scaphopda ::
Scaphopda (n. pl.) A class of marine cephalate Mollusca having a tubular shell open at both ends, a pointed or spadelike foot for burrowing, and many long, slender, prehensile oral tentacles. It includes Dentalium, or the tooth shells, and other similar shells. Called also Prosopocephala, and Solenoconcha..
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