The word Invertebrate is used to describe animals that lack a spinal column. Approximately 97% of all animals are invertebrates.
Phylum Mollusca is a very large and diverse group that consists of 112,000 species of different animals. Some common animals found under this phylum include squid and oysters. All mollusks are protostomes and are bilaterally symmetrical. They have a true coelom which means they have a true body cavity They also have a mantle as well as a muscular foot that is used for locomotion.
Under Phylum Mollusca, Class Gastropoda is found. It is the most diverse class of mollusks that includes snails and limpets. Snails and limpets share a common characteristic: a muscular foot for movement. They also share a similar body plan.Snails can be found in all kinds of environments, including terrestrial, fresh water and marine. Limpets are usually find near the shoreline or on "inter-tidal rock substrates" as well as marine grasses.