A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. Land snail is the common name for terrestrial gastropod mollusks that have shells. However, it is not always easy to say which species are terrestrial, because some are more or less amphibious between land and fresh water, and others are relatively amphibious between land and salt water.
Helix pomatia, a species of air-breathing land snail used for escargot, is a little bit larger than the common garden snail.
Cornu aspersum (previously Helix aspersa) – the common garden snail – in Israel
Colonies of snails in Sicily
"The Teeth of a Snail" from Robert Hooke's Micrographia, 1665. This actually shows the jaw, against which the teeth on the radula act.
A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name snail is also used for most of the members of the molluscan class Gastropoda that have a coiled shell that is large enough for the animal to retract completely into. When the word "snail" is used in this most general sense, it includes not just land snails but also numerous species of sea snails and freshwater snails. Gastropods that naturally lack a shell, or have only an internal shell, are mostly called slugs, and land snails that have only a very small shell are often called semi-slugs.
Snail
Helix pomatia sealed in its shell with a calcareous epiphragm
Slug
Cornu aspersum – garden snail