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Snail slime (''
Experimental Biology
' article, research has been presented showing that each wave is indeed creating a propulsive force using the mucus to reduce resistance. Land mollusks travel by adhesive locomotion via muscular waves that propagate from tail to head. The snail mucus has an adapted flow behavior that allows transmittance of the muscular force while maintaining adhesion. When inactive, many mollusks of both marine and terrestrial species, use the secretion to stick to various surfaces. However, although it is so diluted that it can commonly act as a lubricant, it can also have strong adhesive properties. In their unique mating ritual, '' Limax maximus'' use a mucus thread to suspend themselves from elevated locations like tree branches. In ''Cornu aspersum'', there are two types of secretion. One type is translucent and not adhesive, the kind that the snail leaves behind as it moves (the slime trail), and the other is similar but thicker, condensed, more viscous and elastic, which is used to adhere to various surfaces. Both are clearly differentiated by the type of proteins present in them.
Snail slime (''mucopolysaccharide
Glycosaminoglycans (GAGs) or mucopolysaccharides are long, linear polysaccharides consisting of repeating disaccharide units (i.e. two-sugar units). The repeating two-sugar unit consists of a uronic sugar and an amino sugar, except in the case o ...
'') is a kind of mucus
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 ...
(an external bodily secretion) produced by snails
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 Gastro ...
, which are gastropod mollusk
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 e ...
s. 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.
Externally, one kind of mucus is produced by the foot of the gastropod and is usually used for crawling. The other kind of external mucus has evolved to coat the external parts of the gastropod's body; in land species, this coating helps prevent desiccation of the exposed soft tissues. The foot mucus of a gastropod has some of the qualities of glue and some of the qualities of a lubricant, allowing land snails to crawl up vertical surfaces without falling off.
The slime trail that a land gastropod leaves behind is often visible as a silvery track on surfaces such as stone or concrete.
Description
Mucus is agel
A gel is a semi-solid that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state, although the liquid phase may still dif ...
consisting of a polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
network that functions as a protective layer for the integument
In biology, an integument is the tissue surrounding an organism's body or an organ within, such as skin, a husk, shell, germ or rind.
Etymology
The term is derived from ''integumentum'', which is Latin for "a covering". In a transferred, or ...
and mucosal surfaces of both elementary animals and mammals.
The mucus of gastropods is not only used as a coating to cover the surfaces on which the snail crawls and a coating to cover the exposed soft parts of the body but also sometimes to allow a resting snail to adhere passively to surfaces, such as rock, making a temporary sealing structure called the epiphragm
An epiphragm (from the Ancient Greek ἐπί, '' epi '' " upon, on, over " and φράγμα, '' -phrágma '' "fence") is a temporary structure which can be created by many species of shelled, air-breathing land snails, terrestrial pulmonate gast ...
. Mucus is produced by a large gland located below the snail's mouth.
The foot of gastropods is covered with a thin layer of this mucus, which is used for a variety of functions, including locomotion, adherence, lubrication, repulsing predators, recognizing other snails, following a trail to a known destination and during reproduction. The discharge looks like a gel and it contains approximately 91 to 98% water by weight, depending on the species, combined with a small amount of high molecular weight glycoproteins (Denny, 1984). In ''Cornu aspersum'', these glycoproteins reach weights of 82, 97 and 175 kDa.
Locomotion
Locomotion in snails comes from a series of muscle contractions called pedal waves and relaxations called inter waves. The waves created help propel the snail forward whilst pushing the thin layer of mucus used as lubrication, behind them. In anExperimental Biology
' article, research has been presented showing that each wave is indeed creating a propulsive force using the mucus to reduce resistance. Land mollusks travel by adhesive locomotion via muscular waves that propagate from tail to head. The snail mucus has an adapted flow behavior that allows transmittance of the muscular force while maintaining adhesion. When inactive, many mollusks of both marine and terrestrial species, use the secretion to stick to various surfaces. However, although it is so diluted that it can commonly act as a lubricant, it can also have strong adhesive properties. In their unique mating ritual, '' Limax maximus'' use a mucus thread to suspend themselves from elevated locations like tree branches. In ''Cornu aspersum'', there are two types of secretion. One type is translucent and not adhesive, the kind that the snail leaves behind as it moves (the slime trail), and the other is similar but thicker, condensed, more viscous and elastic, which is used to adhere to various surfaces. Both are clearly differentiated by the type of proteins present in them.
Slime Production
A snail releases different kinds of mucus depending on the way it is stimulated. When the stimulation is normal, the slime is viscous (sticky) but if the snail is disturbed continuously or even violently, it releases clear foamy secretions. If the snail is sexually aroused the slime it releases is clear and viscous (sticky). In the case of ''Cornu aspersum
''Cornu aspersum'' (syn. ''Cryptomphalus aspersus''), known by the common name garden snail, is a species of land snail in the family Helicidae, which includes some of the most familiar land snails. Of all terrestrial molluscs, this species may ...
'', the discharge is composed of synthesized products from various types of secretory glands. These are all single-cell glands found in connective tissue and they secrete their products via pores that pass between the epidermal cells
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water relea ...
. They are of various shapes and usually have a long excretory duct. There are eight different types of secreting glands. Four of these different types secrete protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
, calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...
, pigment
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...
s and lipid
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids includ ...
s.Campion, M. (1961). The structure and function of the cutaneous glands in Helix aspersa. Journal of Microscopical Science. 102(2): 195-216
Medical Uses
Some of the characteristics of snail slime have shown to be useful in Chinese medicine. Traditional Chinese medicine has used slime in a variety of ways to treat a variety of illness and cosmetic issues. "For examples, snail powders can treat urinary obstruction by putting them above navel, can prevent nosebleed by blowing the powers into nostrils, can cure deaf by dropping snail powers/wine solution into the ears, can soothe toothache and laryngeal diseases. Furthermore the snail solution obtained by putting snails in water or wine can be used for curing hemorrhoids, boils, scrofulous, scars, and acne. It has also been used as skin creams for wrinkles and dry skin in cosmetics." The Chinese also have used the color-fast dry qualities of snail slime as a natural dye that represented wealth and power. The mucus has shown to be proficient in several biological activities including antimicrobial, antioxidant, anti-tyrosinase, and anti-tumoral activities.
See also
*Heliciculture
Heliciculture, commonly known as snail farming, is the process of raising edible land snails, primarily for human consumption or cosmetic use. The meat and snail eggs a.k.a. ''white caviar'' can be consumed as escargot and as a type of caviar, r ...
* Mucus
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 ...
* Mucous pedal gland
References