page_title: Snail
section_title: Slugs
hierarchical_section_title: Snail / Slugs
caption_attribution_description: English: Photo of snail without shell
context_page_description: A snail is, in loose terms, 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.
  Snails have considerable human relevance, including as food items, as pests, and as vectors of disease, and their shells are used as decorative objects and are incorporated into jewelry. The snail has also had some cultural significance, tending to be associated with patience. The snail has also been used as a metaphor: someone who is not moving fast enough is "slow as a snail." The snail is the same or similar shape as the Cochlea.
context_section_description: Gastropods that lack a conspicuous shell are commonly called slugs rather than snails. Some species of slug have a maroon-brown shell, some have only an internal vestige that serves mainly as a calcium lactate repository, and others have some to no shell at all. Other than that there is little morphological difference between slugs and snails. There are however important differences in habitats and behavior.
  A shell-less animal is much more maneuverable and compressible, so even quite large land slugs can take advantage of habitats or retreats with very little space, retreats that would be inaccessible to a similar-sized snail. Slugs squeeze themselves into confined spaces such as under loose bark on trees or under stone slabs, logs or wooden boards lying on the ground. In such retreats they are in less danger from either predators or desiccation. Those are often suitable places for laying their eggs.
  Slugs as a group are far from monophyletic; scientifically speaking "slug" is a term of convenience with little taxonomic significance. The reduction or loss of the shell has evolved many times independently within several very different lineages of gastropods. The various taxa of land and sea gastropods with slug morphology occur within numerous higher taxonomic groups of shelled species; such independent slug taxa are not in general closely related to one another.
caption: Slug
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