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.
The gastropods, commonly known as slugs and snails, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda.
Helix is a genus of large, air-breathing land snails native to the western Palaearctic and characterized by a globular shell. It is the type genus of the family Helicidae, and one of the animal genera described by Carl Linnaeus. Members of the genus first appeared during the Miocene. Well-known species include Helix pomatia and Helix lucorum. Cornu aspersum, though externally similar and long classified as a member of Helix, is not closely related to Helix and belongs to a different tribe of Helicinae.
Mucus is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is a viscous colloid containing inorganic salts, antimicrobial enzymes, immunoglobulins, and glycoproteins such as lactoferrin and mucins, which are produced by goblet cells in the mucous membranes and submucosal glands. Mucus serves to protect epithelial cells in the linings of the respiratory, digestive, and urogenital systems, and structures in the visual and auditory systems from pathogenic fungi, bacteria and viruses. Most of the mucus in the body is produced in the gastrointestinal tract.
The endostyle is an anatomical feature found in invertebrate chordates and larval lampreys. It is an organ which assists chordates in filter-feeding. It is found in adult urochordates and cephalochordates, as well as in the larvae of the vertebrate lampreys, but has been transformed through evolutionary time into the thyroid in all other vertebrates. Since the endostyle is found in all three branches of chordates, it is presumed to have arisen in the common ancestor of these taxa, along with a shift to internal feeding for extracting suspended food from the water.
Helicidae is a large, diverse family of small to large, air-breathing land snails, sometimes called the "typical snails."
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.
Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word slug is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a small internal shell, particularly sea slugs and semi slugs.
Riccardoella limacum or the white snail mite is a member of the Acari (mite) family which is parasitic primarily on snails. Slug mites are very small, white, and can be seen to move very rapidly over the surface of their host, particularly under the shell rim and near the pulmonary aperture. While once thought to be benign mucophages, more recent studies have shown that they actually subsist on the host's blood, and may bore into the host's body to feed.
A love dart is a sharp, calcareous or chitinous dart which some hermaphroditic land snails and slugs create. Love darts are both formed and stored internally in a dart sac. These darts are made in sexually mature animals only, and are used as part of the sequence of events during courtship, before actual mating takes place. Darts are quite large compared to the size of the animal: in the case of the semi-slug genus Parmarion, the length of a dart can be up to one fifth that of the semi-slug's foot.
Leidyula floridana, common name the Florida leatherleaf, is a species of tropical air-breathing land slug, shell-less terrestrial pulmonate gastropod mollusks in the family Veronicellidae.
Milax is a genus of air-breathing, keeled, land slugs. These are shell-less terrestrial gastropod mollusks in the family Milacidae.
The sensory organs of gastropods include olfactory organs, eyes, statocysts and mechanoreceptors. Gastropods have no sense of hearing.
The reproductive system of gastropods varies greatly from one group to another within this very large and diverse taxonomic class of animals. Their reproductive strategies also vary greatly, see Mating of gastropods.
The digestive system of gastropods has evolved to suit almost every kind of diet and feeding behavior. Gastropods as the largest taxonomic class of the mollusca are very diverse: the group includes carnivores, herbivores, scavengers, filter feeders, and even parasites.
The caudal mucous pit, or caudal mucous horn, is an anatomical structure on the tail end of the foot of various land snails and slugs, terrestrial pulmonate gastropod mollusks.
Quantula striata, also known as Dyakia striata, is a species of medium-sized, air-breathing, tropical land snail. It is a terrestrial, pulmonate, gastropod mollusk in the family Dyakiidae. This species appears to be unique among terrestrial gastropods in that it is bioluminescent: Its eggs glow in the dark, and juveniles and most adults give off flashes of green light. It is the only species in the genus Quantula.
The hypobranchial gland is a glandular structure which is part of the anatomy of many mollusks, including several different families of gastropods, and also many protobranch bivalves. This gland produces mucus as well as biologically active compounds. The cephalopod ink sac is a modified hypobranchial gland.
Snail slime (mucopolysaccharide) is a kind of mucus produced by snails, which are gastropod mollusks. Land snails and slugs both produce mucus, as does every other kind of gastropod, from marine, freshwater, and terrestrial habitats. The reproductive system of gastropods also produces mucus internally from special glands.
This outline is provided as an overview of, and organized list of articles relevant to, the subject of gastropods :
