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A snail is, in loose terms, a shelled
gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
. The name is most often applied to
land 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 (those without shells are known as ...
, terrestrial
pulmonate Pulmonata or pulmonates, is an informal group (previously an order, and before that a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includ ...
gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000  extant species of molluscs are recognized. The number of fossil species is esti ...
s. However, the common name ''snail'' is also used for most of the members of the molluscan class
Gastropoda The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. ...
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 snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...
s and
freshwater snail Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs ...
s. Gastropods that naturally lack a shell, or have only an internal shell, are mostly called ''
slug 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 smal ...
s'', and land snails that have only a very small shell (that they cannot retract into) 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 lethargy. The snail has also been used as a
figure of speech A figure of speech or rhetorical figure is a word or phrase that intentionally deviates from ordinary language use in order to produce a rhetorical effect. Figures of speech are traditionally classified into '' schemes,'' which vary the ordinary ...
in reference to slow-moving things. The snail is the same or similar shape as the cochlea.


Overview

Snails that respire using a
lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
belong to the group
Pulmonata Pulmonata or pulmonates, is an informal group (previously an order, and before that a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includ ...
. As traditionally defined, the Pulmonata were found to be polyphyletic in a molecular study per Jörger ''et al.'', dating from 2010. But snails with gills also form a polyphyletic group; in other words, snails with lungs and snails with gills form a number of
taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
groups that are not necessarily more closely related to each other than they are related to some other groups. Both snails that have lungs and snails that have gills have diversified so widely over geological time that a few species with gills can be found on land and numerous species with lungs can be found in freshwater. Even a few marine species have lungs. Snails can be found in a very wide range of environments, including ditches,
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
s, and the
abyssal The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. "Abyss" derives from the Greek word , meaning bottomless. At depths of , this zone remains in perpetual darkness. It covers 83% of the total area of the ocean an ...
depths of the sea. Although land snails may be more familiar to laymen,
marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...
snails constitute the majority of snail species, and have much greater diversity and a greater
biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
. Numerous kinds of snail can also be found in
fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
. Most snails have thousands of microscopic tooth-like structures located on a banded ribbon-like tongue called a
radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...
. The radula works like a file, ripping food into small pieces. Many snails are herbivorous, eating plants or rasping algae from surfaces with their radulae, though a few land species and many marine species are
omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...
s or predatory carnivores. Snails cannot absorb colored pigments when eating paper or cardboard so their feces are also colored. Several species of the genus '' Achatina'' and related genera are known as giant African land snails; some grow to from snout to tail, and weigh . The largest living species of sea snail is ''
Syrinx aruanus ''Syrinx aruanus'', common name the Australian trumpet or false trumpet, is a species of extremely large sea snail measuring up to 91 cm long and weighing up to 18 kg. It is a marine gastropod mollusk in the family Turbinellidae, and ...
''; its shell can measure up to in length, and the whole animal with the shell can weigh up to . Recently, the smallest land snails, '' Angustopila dominikae,'' have been discovered in China, and measure 0.86mm long. The snail '' Lymnaea'' makes decisions by using only two types of neurons: one deciding whether the snail is hungry, and the other deciding whether there is food in the vicinity. The largest known land gastropod is the African giant snail ''Achatina achatina'', the largest recorded specimen of which measured from snout to tail when fully extended, with a shell length of in December 1978. It weighed exactly 900 g (2 lb). Named Gee Geronimo, this snail was owned by Christopher Hudson (1955–79) of Hove, East Sussex, UK, and was collected in Sierra Leone in June 1976.


Diet

Snails eating habits vary widely, with some being generalists and some being specialist feeders. Snails feed at night. They feed primarily on decaying organic matter. Their diet also includes fungi, lichens, green foliage, worms, centipedes, insects, animal feces, carrion, and other slugs. Some snails feed on other snails too.


Types of snails by habitat


Slugs

Gastropods that lack a conspicuous shell are commonly called
slug 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 smal ...
s rather than snails. Some species of slug have a maroon-brown shell, some have only an internal
vestige Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...
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 In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
; 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.


Human relevance

Land snails are known as an agricultural and garden pest but some species are an edible delicacy and occasionally household pets. In addition, their mucus can also be used for skin care products.


In agriculture

There are a variety of snail-control measures that gardeners and farmers use in an attempt to reduce damage to valuable plants. Traditional pesticides are still used, as are many less toxic control options such as concentrated
garlic Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus ''Allium''. Its close relatives include the onion, shallot, leek, chive, Allium fistulosum, Welsh onion and Allium chinense, Chinese onion. It is native to South A ...
or
wormwood Wormwood may refer to: Biology * Several plants of the genus ''Artemisia'': ** ''Artemisia abrotanum'', southern wormwood ** '' Artemisia absinthium'', common wormwood, grande wormwood or absinthe wormwood ** ''Artemisia annua'', sweet wormwood o ...
solutions. Copper metal is also a snail repellent, and thus a copper band around the trunk of a tree will prevent snails from climbing up and reaching the foliage and fruit. A layer of a dry, finely ground, and scratchy substance such as
diatomaceous earth Diatomaceous earth (), diatomite (), or kieselgur/kieselguhr is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder. It has a particle size ranging from more than 3  μm to le ...
can also deter snails. The
decollate snail The decollate snail, scientific name ''Rumina decollata'', is a medium-sized predatory land snail, a species of terrestrial pulmonate gastropod mollusk in the family Achatinidae. It is a European species that has been introduced in a number o ...
(''Rumina decollata'') will capture and eat garden snails, and because of this it has sometimes been introduced as a
biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...
agent. However, this is not without problems, as the decollate snail is just as likely to attack and devour other gastropods that may represent a valuable part of the native fauna of the region.


As food

In French cuisine, edible snails are served for instance in '' Escargot à la Bourguignonne''. The practice of rearing snails for food is known as heliciculture. For purposes of cultivation, the snails are kept in a dark place in a wired cage with dry straw or dry wood. Coppiced wine-grape vines are often used for this purpose. During the rainy period, the snails come out of
hibernation Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...
and release most of their mucus onto the dry wood/straw. The snails are then prepared for cooking. Their texture when cooked is slightly chewy and tender. As well as being relished as gourmet food, several species of land snails provide an easily harvested source of protein to many people in poor communities around the world. Many land snails are valuable because they can feed on a wide range of agricultural wastes, such as shed leaves in banana plantations. In some countries,
giant African land snail Giant African land snail is the common name of several species within the family Achatinidae, a family of unusually large African terrestrial snails: * ''Achatina achatina'', also known as the agate snail or Ghana tiger snail * ''Lissachatina fulic ...
s are produced commercially for food. Land snails, freshwater snails and sea snails are all eaten in many countries. In certain parts of the world, snails are fried as for example, in Indonesia, they are fried as satay, a dish known as ''
sate kakul Satay ( , in USA also , ), or sate in Indonesian spelling, is a Southeast Asian dish of seasoned, skewered and grilled meat, served with a sauce. The earliest preparations of satay is believed to have originated in Javanese cuisine, but ...
''. The eggs of certain snail species are eaten in a fashion similar to the way caviar is eaten. In Bulgaria, snails are traditionally cooked in an oven with rice or fried in a pan with vegetable oil and red paprika powder. Before they are used for those dishes, however, they are thoroughly boiled in hot water (for up to 90 minutes) and manually extracted from their shells. The two species most commonly used for food in the country are ''
Helix lucorum ''Helix lucorum'' is a species of large, edible, air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Helicidae, the typical snails. MolluscaBase eds. (2020). MolluscaBase. Helix lucorum Linnaeus, 1758. Accessed throu ...
'' and ''
Helix pomatia ''Helix pomatia'', common names the Roman snail, Burgundy snail, or escargot, is a species of large, edible, air-breathing land snail, a pulmonate gastropod terrestrial mollusc in the family Helicidae.MolluscaBase eds. (2021). MolluscaBase. ...
''.


Famine food

Snails and slug species that are not normally eaten in certain areas have occasionally been used as famine food in historical times. A history of Scotland written in the 1800s recounts a description of various snails and their use as food items in times of plague.


Parasitic diseases

Snails can also be associated with parasitic diseases such as
schistosomiasis Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever, is a disease caused by parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Symptoms include abdominal pain, diarrhea, bloody s ...
,
angiostrongyliasis Angiostrongyliasis is an infection by a roundworm of the '' Angiostrongylus'' type. Symptoms may vary from none, to mild, to meningitis. Infection with ''Angiostrongylus cantonensis'' (rat lungworm) can occur after ingestion of raw or undercoo ...
, fasciolopsiasis, opisthorchiasis,
fascioliasis Fasciolosis is a helminth, parasitic worm infection caused by the common liver fluke ''Fasciola hepatica'' as well as by ''Fasciola gigantica''. The disease is a plant-borne Trematoda, trematode zoonosis, and is classified as a Neglected tropic ...
, paragonimiasis and
clonorchiasis Clonorchiasis is an infectious disease caused by the Chinese liver fluke (''Clonorchis sinensis'') and two related species. Clonorchiasis is a known risk factor for the development of cholangiocarcinoma, a neoplasm of the biliary system. Sympt ...
, which can be transmitted to humans.


Cultural depictions


Symbolism

Because of its slowness, the snail has traditionally been seen as a symbol of laziness. In Christian culture, it has been used as a symbol of the
deadly sin The seven deadly sins, also known as the capital vices or cardinal sins, is a grouping and classification of vices within Christian teachings. Although they are not directly mentioned in the Bible, there are parallels with the seven things ...
of sloth. Psalms uses snail slime as a metaphorical punishment. In Mayan mythology, the snail is associated with sexual desire, being
personified Personification occurs when a thing or abstraction is represented as a person, in literature or art, as a type of anthropomorphic metaphor. The type of personification discussed here excludes passing literary effects such as "Shadows hold their ...
by the god Uayeb.


Divination and other religious uses

Snails were widely noted and used in
divination Divination (from Latin ''divinare'', 'to foresee, to foretell, to predict, to prophesy') is the attempt to gain insight into a question or situation by way of an occultic, standardized process or ritual. Used in various forms throughout histor ...
. The Greek poet
Hesiod Hesiod (; grc-gre, Ἡσίοδος ''Hēsíodos'') was an ancient Greek poet generally thought to have been active between 750 and 650 BC, around the same time as Homer. He is generally regarded by western authors as 'the first written poet i ...
wrote that snails signified the time to harvest by climbing the stalks, while the Aztec moon god Tecciztecatl bore a snail shell on his back. This symbolised rebirth; the snail's penchant for appearing and disappearing was analogised with the moon.


Love darts and Cupid

Professor Ronald Chase of McGill University in Montreal has suggested the ancient myth of
Cupid In classical mythology, Cupid (Latin Cupīdō , meaning "passionate desire") is the god of desire, lust, erotic love, attraction and affection. He is often portrayed as the son of the love goddess Venus (mythology), Venus and the god of war Mar ...
's arrows might be based on early observations of the love dart behavior of the land snail species ''Cornu aspersum''.


Metaphor

In contemporary speech, the expression "a snail's pace" is often used to describe a slow, inefficient process. The phrase " snail mail" is used to mean regular postal service delivery of paper messages as opposed to the delivery of email, which can be virtually instantaneous. In medieval and Renaissance manuscripts snails are depicted as a comic relief due to the similarity between the armour of knights and the shell of snails.


In Indonesian mythology

Keong Emas ( Javanese and
Indonesian Indonesian is anything of, from, or related to Indonesia, an archipelagic country in Southeast Asia. It may refer to: * Indonesians, citizens of Indonesia ** Native Indonesians, diverse groups of local inhabitants of the archipelago ** Indonesian ...
for Golden Snail) is a popular Javanese folklore about a princess magically transformed and contained in a golden snail shell. The folklore is a part of popular Javanese
Panji cycle The Panji tales (formerly spelled Pandji) are a cycle of Javanese stories, centred around the legendary prince of the same name from East Java, Indonesia. Along with the Ramayana and Mahabharata, the tales are the basis of various poems and a ge ...
telling the stories about the prince Panji Asmoro Bangun (also known as Raden Inu Kertapati) and his consort, princess Dewi Sekartaji (also known as Dewi Chandra Kirana).


Textiles

Certain varieties of snails, notably the family Muricidae, produce a secretion that is a color-fast natural dye. The ancient Tyrian purple was made in this way as were other purple and blue dyes. The extreme expense of extracting this secretion is sufficient quantities limited its use to the very wealthy. It is such dyes as these that led to certain shades of purple and blue being associated with royalty and wealth.


As pets

Throughout history, snails have been kept as pets. There are many famous snails such as Lefty (Born Jeremy) and within fiction,
Gary Gary may refer to: *Gary (given name), a common masculine given name, including a list of people and fictional characters with the name *Gary, Indiana, the largest city named Gary Places ;Iran *Gary, Iran, Sistan and Baluchestan Province ;Unit ...
and Brian the snail.


See also

* Gastropod shell *
Pasilalinic-sympathetic compass The pasilalinic-sympathetic compass, also referred to as the snail telegraph, was a contraption built to test the pseudo-scientific hypothesis that snails create a permanent telepathy, telepathic link when they mate. The device was developed by F ...
* Jeremy (snail) *
Land snail 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 (those without shells are known as ...
*
Freshwater snail Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs ...
*
Sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...


References


Gallery

File:The snail 1 నత్త.jpg, A snail File:Snail climbing stone slabs.png, Snail climbing stone slabs at Servia, Greece. The shell is so heavy that its bottom side becomes visible. File:SeaSnails.ogv, Snails feeding on the sea floor (50 sec) File:Snail Melc melc codobelc.ogv, Video of snail after rain (31 sec) File:Snail moving on ground.webm, Snail moving on a wet ground File:Snail moving across leaves.webm, Snail moving across leaves.


External links


Introduction to Snails
Infoqis Publishing, Co. {{Authority control Articles containing video clips Mollusc common names * Paraphyletic groups