Snail
Snails | |
---|---|
Helix pomatia, a species of land snail | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Gastropoda |
A snail is a shelled
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.[1] 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 in reference to slow-moving things.
Overview
Snails that
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
Most snails have thousands of microscopic tooth-like structures located on a banded ribbon-like tongue called a radula. 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 omnivores or predatory carnivores. Snails cannot absorb colored pigments when eating paper or cardboard so their feces are also colored.[3]
Several species of the genus Achatina and related genera are known as giant African land snails; some grow to 15 in (38 cm) from snout to tail, and weigh 1 kg (2 lb).[4] The largest living species of sea snail is Syrinx aruanus; its shell can measure up to 90 cm (35 in) in length, and the whole animal with the shell can weigh up to 18 kg (40 lb). Recently, the smallest land snails, Angustopila dominikae, have been discovered in China, and measure 0.86mm long.[5]
The largest known land gastropod is the African giant snail Achatina achatina, the largest recorded specimen of which measured 39.3 centimetres (15.5 in) from snout to tail when fully extended, with a shell length of 27.3 cm (10.7 in) 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.[6]
Snails are protostomes. That means during development, in the gastrulation phase, the blastopore forms the mouth first. Cleavage in snails is spiral holoblastic patterning. In spiral holoblastic cleavage, the cleavage plane rotates each division and the cell divisions are complete. Snails do not undergo metamorphosis after hatching. Snails hatch in the form of small adults. The only additional development they will undergo is to consume calcium to strengthen their shell. Snails can be male, female, hermaphroditic, or parthenogenetic so there are many different systems of sexual determination.
Diet
Snails' eating habits vary widely, with some being generalists and some being specialist feeders.[7] Snails feed at night.[8] They feed primarily on decaying organic matter.[8] Their diet also includes fungi, lichens, green foliage, worms, centipedes, insects, animal feces, carrion, and other slugs.[8] Some snails feed on other snails too.[8]
Types of snails by habitat
Slugs
This section
relies largely or entirely on a single source. (March 2018) |
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.
Human relevance
This section needs additional citations for verification. (March 2018) |
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.[10]
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 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. A layer of a dry, finely ground, and scratchy substance such as diatomaceous earth can also deter snails.[11]
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 gastropods that may represent a valuable part of the native fauna of the region.
Culinary use
In
As well as being eaten as gourmet food, several species of land snails provide an easily harvested source of
Land snails, freshwater snails and sea snails are all eaten in many countries. In certain parts of the world snails are fried. For example, in Indonesia, they are fried as satay, a dish known as sate kakul. The eggs of certain snail species are eaten in a fashion similar to the way caviar is eaten.[12]
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 and Helix pomatia.[citation needed]
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.[13]
Parasitic diseases
Snails can also be associated with parasitic diseases such as
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
Divination and other religious uses
Snails were widely noted and used in
Love darts and Cupid
Professor Ronald Chase of McGill University in Montreal has suggested the ancient myth of Cupid's arrows might be based on early observations of the love dart behavior of the land snail species Cornu aspersum.[18]
Metaphor
In contemporary speech, the expression "a snail's pace" is often used to describe a slow, inefficient process. The phrase "
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.[19]
In Indonesian mythology
Keong Emas (
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.[20][21][22] 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.[23]
As pets
Throughout history, snails have been kept as pets. There are many famous snails such as
See also
References
- ^ "Snails used in Jewellery".
- PMID 20973994.
- ^ "Floor tiles made of coloured snail poo by Lieske Schreuder - design". 26 November 2013. Retrieved 29 March 2018.
- ISBN 9780811736220. Retrieved 19 June 2012.
- ^ Hogenboom, Melissa (27 July 2020). "The world's smallest snail has been discovered". BBC.
- ^ "Largest Snail". Guinness World Records. Retrieved 17 December 2016.
- ^ Vendetti, Jann. "A Microscopic Look at Snail Jaws". nhm.org. Natural History Museum Los Angeles County. Retrieved 2022-01-05.
- ^ ISBN 9780292709379.
- ^ "Slug vs Snail - Difference and Comparison - Diffen". Retrieved 29 March 2018.
- ^ Howley, Elaine (18 July 2022). "Snail Mucin for Skin Care: Products and Uses". U.S. News. Archived from the original on 18 July 2023. Retrieved 29 July 2023.
- SF Gate. Accessed 01 July 2019.
- ^ "The height of slow-food, France serves snail caviar". Reuters. 20 December 2007.
- W. & R. Chambers. (Also quoted here.
- ^ ISBN 978-0-7204-8021-4.
- ISBN 978-0-7607-8164-7.
- ^ Susan Milbrath, Star Gods of the Maya: Astronomy in Art, Folklore, and Calendars, University of Texas Press, 01/01/2010
- ISBN 978-1-85538-118-6.
- ^ Mayell, Hillary (February 13, 2004). "Lovebirds and Love Darts: The Wild World of Mating". news.national-geographic.com. National Geographic Society. Archived from the original on January 9, 2006. Retrieved 2010-02-21.
- ^ Monge-Nájera, J. (2019). Pulmonate snails as marginalia in medieval and Renaissance manuscripts: a review of hypotheses. Darwin In Memoriam: History of Science. BLOG RPT.https://revistas.ucr.ac.cr/index.php/rbt/article/view/38872
- ISSN 1472-3581.
- ^ Biggam, Carole P. (March 2006). "Whelks and purple dye in Anglo-Saxon England" (PDF). The Archeo+Malacology Group Newsletter (9).
- ISBN 978-1-57506-042-2.
- LCCN 10011191.
- ^ "BBC Radio 3 – Slow Radio – Seven of the world's most famous snails". BBC. Retrieved 2020-02-14.
Gallery
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A snail
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Snail climbing stone slabs at Servia, Greece. The shell is so heavy that its bottom side becomes visible.
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Snails feeding on the sea floor (50 sec)
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Video of snail after rain (31 sec)
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Snail moving on a wet ground
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Snail moving across leaves.
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Snails in the Hyblaean Mountains.
External links
- Introduction to Snails, Infoqis Publishing, Co.