Mollusca

Mollusca məlŭsˈkə [key], taxonomic name for the one of the largest phyla of invertebrate animals (Arthropoda is the largest) comprising more than 50,000 living mollusk species and about 35,000 fossil species dating back to the Cambrian period. Mollusks are soft-bodied, and most have a prominent shell. The members of this highly successful and diverse phylum are mostly aquatic and include the familiar scallop, clam, oyster, mussel, snail, slug, squid, cuttlefish, octopus, chiton, and a variety of others. Mollusks occupy habitats ranging from the deep ocean to shallow waters to moist terrestrial niches. Certain mollusks, such as clams, squids, and scallops, constitute important food staples, and molluskan shells are highly valued by collectors. In times past these shells were used as money and today are used ornamentally for such items as buttons and jewelry. There are seven classes of mollusks.

Sections in this article:

• Introduction
• Class Cephalopoda
• Class Scaphopoda
• Class Bivalvia
• Class Gastropoda
• Class Monoplacophora
• Class Polyplacophora
• Class Aplacophora
• Reproduction
• Circulatory and Nervous Systems
• Respiration
• The Digestive Tract
• The Shell
• The Body Wall
• Anatomical Features

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2024, Columbia University Press. All rights reserved.

See more Encyclopedia articles on: Zoology: Invertebrates