The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to Achatina achatina, the largest known land gastropod. There are many thousands of species of sea snails and sea slugs, as well as freshwater snails, freshwater limpets, land snails and land slugs.
The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossilhistory of this class goes back to the Late Cambrian. As of 2017, there are 721 families of gastropods known, of which 245 are extinct and appear only in the fossil record and 476 occur in the Recent with or without a 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 65,000 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.
The class Gastropoda has an extraordinary diversification of habitats.
