The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomicclass within the phylumMollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to large. There are many thousands of species of sea snails and sea slugs, as well as freshwater snails and freshwater limpets, as well as land snails and land slugs.
The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. There are 611 families of gastropods, of which 202 families are extinct and appear only in the fossil record.
Gastropoda (previously known as univalves and sometimes spelled Gasteropoda) are a major part of the phylum Mollusca and are the most highly diversified class in the phylum, with 60,000 to 80,000 living snail and slug species. The anatomy, behavior, feeding and reproductive adaptations of gastropods vary significantly from one clade or group to another. Therefore, it is difficult to state many generalities for all gastropods.