Definitions for "Mollusca"
One of the grand divisions of the animal kingdom, a phylum including the classes Cephalopoda, Gastropoda, Pteropoda, Scaphopoda, and Pelecyopoda (syn. Bivalvia, formerly called 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 multivalve.
Phylum which includes soft-bodied organisms either having an external shell which is single, double, or of eight plates or having an internal shell (as in a squid or octopus). This phylum includes many easily recognizable Chesapeake Bay species including oysters and clams.
a large group of invertebrates, found primarily in salt water, including clasm, oysters, and snails. Most mollusks have a hard, limy outer shell protecting a soft body, but some, as in the squid and octopus, lack this type of shell. Many have a muscular foot found ventrally.