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Helix aspersa

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Cornu aspersa
Garden snail (Cornu aspersum) on Limonium
Conservation status
NE
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
(unranked): clade Heterobranchia
clade Euthyneura
clade Panpulmonata
clade Eupulmonata
clade Stylommatophora

informal group Sigmurethra

Superfamily: Helicoidea
Family: Helicidae
Genus: Cornu
Species: C. aspersum
Binomial name
Cornu aspersum
(O. F. Müller, 1774)

Cornu aspersum, known by the common name garden snail, is a species of land snail, a terrestrial pulmonate gastropod mollusc in the family Helicidae, the most commonly familiar land snails. This species may well be the most widely known of all terrestrial molluscs. In English texts it was long classified under the name Helix aspersa, but the prevailing classification places it in the genus Cornu.

Cornu aspersum is native to the Mediterranean area and western Europe, but either deliberately or accidentally, humans have spread it to temperate and subtropical areas world wide. The snail is edible and as such it is relished, but it is widely regarded as a pest in gardens and in agriculture, especially in regions where it has been accidentally introduced and where snails are not usually eaten.

Description

Cornu aspersum
Senestre form (exceptional) and dextral form (common) MHNT

The adult bears a hard, thin calcareous shell 25–40 mm in diameter and 25–35 mm high, with four or five whorls. The shell is variable in color and shade but is generally dark brown or chestnut with yellow stripes, flecks, or streaks.

The body is soft and slimy, brownish-grey, and the animal retracts itself entirely into the shell when inactive or threatened. It has no operculum; during dry or cold weather it seals the aperture of the shell with a thin membrane of dried mucus; the term for such a membrane is epiphragm. The epiphragm helps the snail retain moisture and protects it from small predators such as some ants.

The snail's quiescent periods during heat and drought are known as aestivation; its quiescence during winter is known as hibernation. When hibernating, Cornu aspersum avoids ice formation by altering the osmotic components of its blood (or haemolymph), and it can survive temperatures as low as -5°C (23°F). During aestivation, the mantle collar has the ability to change its permeability to water. It also has an osmoregulatory mechanism that prevents excessive absorption of water during hibernation. These mechanisms allow Cornu aspersum to avoid fatal desiccation during several months of either kind of quiescence.

During times of activity the the snail's head and foot emerge. The head bears four tentacles, the upper two are larger and bear eye-like light sensors, and the lower two are tactile and olfactory sense organs. The snail extends the tentacles by internal pressure of body fluids, and retracts all four tentacles into the head by invagination when threatened or otherwise retreating into its shell. The mouth is located beneath the tentacles, and contains a chitinous radula with which the snail scrapes and manipulates food particles.

Taxonomy

Between 1774 and 1988 all authorities accepted the species as a member of the genus Helix. However, in a number of publications since 1990, it has been placed in one of three other genera, depending on the classification in relation to Helix aperta and on the accepted interpretation of the ICZN Code's Article 1.3.2 on the Cornu problem. For those who regard Cornu as appropriate, the name can be Cornu aspersum if they prefer not to classify it in Helix. Those who prefer neither Cornu nor Helix, fall into two camps; if they classify Helix aperta in the same genus as Helix aspersa, as was done by Italian research teams and others, then they assign this species to Cantareus aspersus; Other workers, such Ukrainian and Russian research teams who regard the two species as being in different genera, call it Cryptomphalus aspersus. The matter is still subject to resolution.

Life cycle

Like other Pulmonata, Cornu aspersum is a hermaphrodite, producing both male and female gametes. Reproduction is usually sexual, although self-fertilisation sometimes occurs. During a mating session of several hours, two snails exchange sperm. Cornu aspersum is one of the species that uses love darts during mating.

About two weeks after fertilisation, the snail lays a batch of about 80 spherical pearly-white eggs into crevices in the topsoil or sheltered under stones or the like. In a year it may lay six batches or so. The size of the egg is 4 mm.

The young snails take one to two years to reach maturity. In some regions snail farms produce them commercially.

Distribution

A hibernaculum on a doocot in Eglinton, Scotland
Garden snail in Israel where it is active in winter nights.

Cornu aspersum is native to the Mediterranean region (including Egypt) and western Europe, from northwest Africa and Iberia, eastwards to Asia Minor, and northwards to the British Isles.

It includes a number of north African endemic forms and subspecies that were described at the beginning of the 20th century, on the basis of shell characteristics. The commonest subspecies, Cornu aspersum aspersum (synonym Helix aspersa aspersa), has become very abundant, mainly in agricultural and residential human habitats where the climates is temperate, Mediterranean, or subtropical.

Cornu aspersum is a typically anthropochorous species; it has been spread to many geographical regions by humans, either deliberately or accidentally. Nowadays it is cosmopolitan in temperate zones, and has become naturalised in many regions with climates that differ from the Mediterranean climate in which it evolved. It is present on all continents except Antarctica, and occurs on most major islands as well. Its passive anthropochory is the likeliest explanation for genetic resemblances between allopatric populations. Its anthropochorous spread may have started as early as during the Neolithic revolution some 8500 BP. Such anthropochory continues, sometimes resulting in catastrophic destruction of habitat or crops.

Its increasing non-native distribution includes other parts of Europe, such as Bohemia in the Czech Republic since 2008. It is present in Australia, New Zealand, North America and southern South America. It was introduced to Southern Africaas a food animal by Huguenots in the 18th century, and into California as a food animal in the 1850s; it is now a notorious agricultural pest in both regions, especially in citrus groves and vineyards. Many jurisdictions have quarantines for preventing the importation of the snail in plant matter.

Ecology

Hundreds of Cornu aspersum on a wall

Cornu aspersum is a primarily a herbivore with a wide range of host plants. It feeds on numerous types of fruit trees, vegetable crops, garden flowers, and cereals. It also is an omnivorous scavenger that feeds on rotting plant material and on occasion will scavenge animal matter, such as crushed snails and worms. In turn it is a food source for many other animals, including small mammals, many bird species, lizards, frogs, centipedes, predatory insects such as glowworms in the family Lampyridae, and predatory terrestrial snails.

The species may on occasion be of use as an indicator of environmental pollution, because it deposits heavy metals, such as lead in its shell.

Mating Cornu aspersum.


Parasites

Parasites of Cornu aspersum include:

Behavior

Cornu aspersum feeding in captivity

The snail's muscular foot contracts to move the animal, and secretes mucus to facilitate locomotion by reducing friction against the substrate. It moves at a top speed of 1.3 centimetres per second (47 meters per hour or ~50 yards per hour), and has a strong homing instinct, readily returning to a regular hibernation site.

Human relevance

Garden snail in Israel.

The species is known as an agricultural and garden pest, an edible delicacy, and occasionally a household pet. In French cuisine, it is known as petit gris, and is served for instance in Escargot a la Bordelaise. 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 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.

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 or wormwood 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. Caffeine has proven surprisingly toxic to snails, to the extent that spent coffee grounds (genuine coffee, and not decaffeinated) make a safe and immediately effective snail-repellant and even molluscicidal mulch for pot-plants, or for wherever else the supply is adequate.

The decollate snail (Rumina decollata) will capture and eat garden snails, and because of this it has sometimes been introduced as a biological pest control agent. However, this is not without problems, as the decollate snail is just as likely to attack and devour other species of gastropods that may represent a valuable part of the native fauna of the region.

Recently, Cornu aspersum has gained some popularity as the chief ingredient in skin creams and gels (crema/gel de caracol) sold within the Latino community in the USA. These creams are promoted as being suitable for use on wrinkles, scars, dry skin, and acne. Since 2013, a snail farmer offers the Snail slime certified organic by ECOCERT.

A screen of the secretions that the Cornu aspersum snail produces under stress, to find if it possesses pharmacological properties, has yielded skin-regenerative properties. Some of the cellular and molecular effects underlying this observation are: the secretions contain antioxidant Superoxide dismutase and Glutathione S-transferase (GSTs) activities. In addition, the secretions stimulate fibroblast proliferation and rearrangement of the actin cytoskeleton. Additional mechanisms involved in the regenerative effect of the snail secretions include the stimulation of extracellular matrix assembly and the regulation of metalloproteinase activities. Together, these effects provide an array of molecular mechanisms underlying the secretions’ induced cellular regeneration and postulate its use in regeneration of wounded tissue.

References

This article incorporates CC-BY-2.0 text from reference.

  1. IUCN (2008). 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 23 February 2009.
  2. Müller O. F. (1774). Vermivm terrestrium et fluviatilium, seu animalium infusoriorum, helminthicorum, et testaceorum, non marinorum, succincta historia. Volumen alterum. pp. I-XXVI [= 1-36], 1-214, [1-10]. Havniae & Lipsiae. (Heineck & Faber).
  3. Ansart A., Vernon P., Daguzan J. 2002. Elements of cold hardiness in a littoral population of the land snail Cornu aspersum (Gastropoda: Pulmonata). Journal of Comparative Physiology B, 172, 619-625.
  4. Machin J. 1966. The evaporation of water from Cornu aspersum IV. Loss from the mantle of the inactive snail. Journal of Experimental Biology, 45, 269-278.
  5. The species was called Cryptomphalus aspersus on p. 244 in the important and widely distributed work Falkner, G. 1990. Binnenmollusken. - pp. 112-280, in: Fechter, R, & Falkner, G.: Weichtiere. Europäische Meeres- und Binnenmollusken. Steinbachs Naturführer 10. -- pp. 1-288. München. (Mosaik).
  6. "The Cornu problem". The Living World of Mollusks. Retrieved 2007-03-05. 
  7. AnimalBase: Genus taxon summary for Cornu (accessed 09 Feb 2011)
  8. Falkner, G., Bank, R. A. & Proschwitz, T. von 2001. Check-list of the non-marine molluscan species-group taxa of the states of northern, Atlantic and central Europe. - Heldia 4 (1/2): 1-76. München.
  9. Falkner, G., Ripken, T. E. J. & Falkner, M. 2002. Mollusques continentaux de France. Liste de référence annotée et bibliographie. - pp. [1-2], 1-350, [1-3]. Paris.
  10. Bank, R., Falkner G. & Proschwitz, T. von 2007. CLECOM-Project. A revised checklist of the non-marine Mollusca of Britain and Ireland. - Heldia 5 (3): 41-72. München.
  11. Manganelli, G., Bodon, M., Favilli, L. & Giusti, F. 1995. Fascicolo 16. Gastropoda Pulmonata. - pp. 1-60, in: Minelli A., Ruffo, S. & La Posta, S.: Checklist delle specie della fauna italiana. Bologna. (Calderini).
  12. Giusti, F., Manganelli, G. & Schembri, P. J. 1995. The non-marine molluscs of the Maltese Islands. - pp. 1-608. Torino.
  13. Neubert, E. 1998. Annotated checklist of the terrestrial and freshwater molluscs of the Arabian Peninsula with descriptions of new species. - Fauna of Arabia 17: 333-461.
  14. Manganelli, G., Salomone, N. & Giusti, F. 2005. A molecular approach to the phylogenetic relationships of the western palaearctic Helicoidea (Gastropoda: Stylommatophora). - Biological Journal of the Linnean Society 85: 501-512.
  15. Sverlova, N. V. 2006. O rasprostranenii nekotorykh vidov nazemnykh mollyuskov na territorii Ukrainy. - Ruthenica 16 (1/2): 119-139. Moskva.
  16. Schileyko, A. A. 2006. Treatise on recent terrestrial pulmonate molluscs, Part 13. Helicidae, Pleurodontidae, Polygyridae, Ammonitellidae, Oreohelicidae, Thysanophoridae. - Ruthenica Supplement 2 (10): 1765-1906.
  17. Egorov, R. 2008. Treasure of Russian shells. Supplement 5. Illustrated catalogue of the recent terrestrial molluscs of Russia and adjacent regions. - pp. 1-179, [1]. Moscow.
  18. Sysoev, A. & Schileyko, A. 2009. Land snails and slugs of Russia and adjacent countries. - pp. 1-312, Fig. 1-142. Sofia. (Pensoft).
  19. Cowie, R. H. (1984). The life-cycle and productivity of the land snail Theba pisana (Mollusca: Helicidae), The Journal of Animal Ecology 53, 311-325
  20. Bezemer T. M. & Knight K. J. 2001. Unpredictable responses of garden snail Helix aspersa populations to climate change. Acta Oecologica, 22, 201-208.
  21. Heller J.: Life History Strategies. in Barker G. M. (ed.): The biology of terrestrial molluscs. CABI Publishing, Oxon, UK, 2001, ISBN 0-85199-318-4. 1-146, cited page: 428.
  22. ^ Arkive: Helix aspersa
  23. Since 2013, a snail farmer and provider for the United States of America USA Snails
  24. Commonwealth of Australia. 2002 (April) Citrus Imports from the Arab Republic of Egypt. A Review Under Existing Import Conditions for Citrus from Israel. Agriculture, Fisheries and Forestry, Australia. Caption: Gastropods, page 12 and Appendix 2.
  25. ^ Annie Guiller A. & Madec L. (2010) "Historical biogeography of the land snail Cornu aspersum: a new scenario inferred from haplotype distribution in the Western Mediterranean basin:. BMC Evolutionary Biology 10: 18. doi:10.1186/1471-2148-10-18
  26. Pfleger, V. & Chatfield, J. (1983). A guide to snails of Britain and Europe. Hamlyn, London.
  27. Juřičková L. & Kapounek F. (18 November 2009) "Helix (Cornu) aspersa (O.F. Müller, 1774) (Gastropoda: Helicidae) in the Czech Republic". Malacologica Bohemoslovaca 8: 53-55. PDF.
  28. UF/IFAS Featured Creatures: Helix aspersa
  29. Fisher TW, Orth RE, Swanson SC. 1980. "Snail against snail." California Agriculture, 34(11): 18-20. Abstract.
  30. Beeby, A., Richmond, L. (1989). The shell as a site of lead deposition in Cornu aspersum, Archives of Environmental Contamination and Toxicology 18, 623-628
  31. (French) Morand S. & Petter A. J. (1986). "Nemhelix bakeri n.gen., n.sp. (Nematoda: Cosmocercinae) parasite de l'appareil génital de Helix aspersa (Gastropoda: Helicidae) en France". Canadian Journal of Zoology 64(9): 2008-2011. doi:10.1139/z86-303.
  32. (French) Morand S. (1988). "Cycle évolutif du Nemhelix bakeri Morand et Petter (Nematoda, Cosmocercidae), parasite de l'appareil génital de l'Helix aspersa Müller (Gastropoda, Helicidae)". Canadian Journal of Zoology 66(8): 1796-1802. doi:10.1139/z88-260.
  33. Speed of a Snail
  34. Velocity Measurement Units Conversion
  35. Attia J. 2004. Behavioural Rhythms of Land Snails in the Field. Biological Rhythm Research, 35: 35-41. Abstract.
  36. [1] Andes Natural Skin Care LLC |date=March 2006
  37. Since 2013, a snail farmer offers the Snail slime [2]
  38. [3] Skin Pharmacology and Physiology. Vol. 21 ISSN: 1660-5527. Molecular basis for the regenerative properties of a secretion of the mollusk Cryptomphalus aspersa. January 2008.
C. aspersum shell cemetery. Individuals failing to overwinter in Scotland.

Further reading

  • Comment on Cornu Born, 1778 (Mollusca, Gastropoda, Pulmonata, HELICIDAE):request for a ruling on the availability of the generic name (Case 3518; see BZN 68: 97–104, 282–292; 69: 124–127, 219–221); Bulletin of Zoological Nomenclature 70(1) March 2013

External links

  • brown garden snail on the UF / IFAS Featured Creatures website
  • Canada Agriculture Fact Sheet
  • BBC Info Page
  • Pesticides Database - Chemical Toxicity Studies
  • Extreme Close-Up Video of the North American Garden Snail
  • University of California Pest Management Guidelines: Brown Garden Snail
  • Zachi Evenor, A video showing a garden snail (Cornu aspersum / Helix aspersa) in action, YouTube, November 9, 2013

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