Snail

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Snails
Snail.jpg
Helix pomatia , a species of land snail
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Helix pomatia sealed in its shell with a calcareous epiphragm Epiphragma einer Weinbergschnecke.JPG
Helix pomatia sealed in its shell with a calcareous epiphragm

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 (that they cannot retract into) are often called semi-slugs .

Contents

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 jewellery. [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 respire using a lung belong to the group Pulmonata. As traditionally defined, the Pulmonata were found to be polyphyletic in a molecular study per Jörger et al., dating from 2010. [2] But snails with gills also form a polyphyletic group; in other words, snails with lungs and snails with gills form a number of taxonomic 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, deserts, and the abyssal depths of the sea. Although land snails may be more familiar to laymen, marine snails constitute the majority of snail species, and have much greater diversity and a greater biomass. Numerous kinds of snail can also be found in fresh water.

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 38 cm (15 in) 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). The smallest land snail, Angustopila psammion, was discovered in 2022 and measures 0.6 mm in diameter. [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 (about 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.

Anatomy

Snails have complex organ systems and anatomies that differ greatly from most animals. Snails and most other Mollusca share three anatomical features; the foot, the mantle, and the radula.

Foot: The foot is a muscular organ used by Gastropods for locomotion. Gastropods' stomachs are located within their foot. Both land and sea snails travel by contracting foot muscles to deform the mucus layer beneath it into different wave-like patterns. [7]

Mantle: The mantle is the organ that produces shells for most species of mollusca. In snails, the mantle secretes the shell along the snail shell opening, continuously growing and producing the shell for the entirety of the snail’s life. [8] The mantle creates a compartment known as the mantle cavity and is used by many mollusca as the surface where gas exchange occurs. Snails that use the mantle cavity as a lung are known as Pulmonate snails. Other snails may only have a gill. Snails in the Caenogastropoda families like Ampullariidae, have both a gill and a lung. [9]

Shell: Snail shells are mainly composed of a mixture of proteins called conchin, and calcium carbonate. Conchin is the main component in the outer layer of the shell, known as the periostracum. The inner layers of the shell are composed of a network of calcium carbonate, conchin, and different mineral salts. The mantle produces the shell through addition around a central axis called the columella, causing a spiraling pattern. [10] The spiraling patterns on a snail’s shell are known as coils or whorls. Whorl size generally increases as the snail ages. Size differences in shell size are believed to be mainly influenced by genetic and environmental components. Moister conditions often correlate with larger snails. In larger populations, adult snails attain smaller shell sizes due to the effects of pheromones on growth rate. [11]

Radula: The radula is an anatomical structure used by most species of Mollusca for feeding. Gastropods are morphologically highly variable and have diverse feeding strategies. Snails can be herbivores, detritivores, scavengers, parasites, ciliary feeders, or have highly specialized predation. [12] Nearly all snails utilize a feeding apparatus including the oral structures of one or more jaws and the radula. The radula comprises a chitinous ribbon with teeth arranged in transverse and longitudinal rows. [13] The radula continually renews itself during the entire lifespan of a mollusk. The teeth and membrane are continuously synthesized in the radular sac and then shifted forward towards the working zone of the radula. The teeth harden and mineralize during their travel to the working zone. The presence of the radula is common throughout most snail species, but often differs in many characteristics, like the shape, size, and number of odontoblasts that form a tooth.

Diet

The average snail's diet varies greatly depending on the species, including different feeding styles from herbivores to highly specialized feeders and parasites. [14] Some snails like the Euglandina rosea, or rosy wolfsnail, are carnivorous and prey on other snails. [15] However, most land snails are herbivores or omnivores. [16] Among land snails, there is also a large variation in preference for specific food. For example, Cepaea nemoralis , or the grove snail, prefers dead plant material over fresh herbs or grasses. Age may also impact food preference, with adult grove snails showing a significantly larger preference for dead plant material than juvenile grove snails. [17] Other snails, like the generalist herbivore Arianta arbustorum , or copse snail, choose their meals based on availability, consuming a mix of arthropods, wilted flowers, fresh and decayed plant material, and soil. [18]

Generally, land snails are most active at night due to the damp weather. The humid nighttime air minimizes water evaporation and is beneficial to land snails because their movement requires mucus, which is mostly composed of water. [16] In addition to aiding movement, mucus plays a vital role in transporting food from the gill to the mouth, cleansing the mantle cavity, and trapping food before ingestion. [19]

Types of snails by habitat

Slugs

Slug Slug 02.jpg
Slug

Gastropods that lack a conspicuous shell are commonly called slugs rather than snails. [20] Some species of slug have a maroon-brown shell, some have only an internal vestige 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; 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.

Parasitic diseases

Snails can also be associated with parasitic diseases such as schistosomiasis, angiostrongyliasis, fasciolopsiasis, opisthorchiasis, fascioliasis, paragonimiasis and clonorchiasis, which can be transmitted to humans.

Human relevance

Cornu aspersum - garden snail Snail-wiki-120-Zachi-Evenor.jpg
Cornu aspersum – garden snail

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. [21]

In agriculture

There is 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. [22]

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.

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. [23] [24] [25] 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. [26]

As pets

Throughout history, snails have been kept as pets. There are many famous snails such as Lefty (Born Jeremy) and within fiction, Gary and Brian the snail. [27]

Culinary use

French cooked snails Cooked snails.JPG
French cooked snails

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 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 eaten 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 snails 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. 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. [28]

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 ]

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. [29]

Cultural depictions

Land snails (Scutalus sp.) on a Moche pot, 200 AD, Larco Museum Collection, Lima, Peru Mochesnail.jpg
Land snails ( Scutalus sp.) on a Moche pot, 200 AD, Larco Museum Collection, Lima, Peru

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 of sloth. [30] [31] In Mayan mythology, the snail is associated with sexual desire, being personified by the god Uayeb. [32]

Snails were widely noted and used in divination. [30] The Greek poet Hesiod 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. [33]

Dewi Sekartaji as Keong Emas Dewi Sekartaji Keong Emas.JPG
Dewi Sekartaji as Keong Emas

Keong Emas (Javanese and 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 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).

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.

See also

Related Research Articles

<span class="mw-page-title-main">Gastropoda</span> Class of molluscs

Gastropods, commonly known as slugs and snails, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda.

The radula is an anatomical structure used by mollusks 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 enters the esophagus. The radula is unique to the mollusks, and is found in every class of mollusk except the bivalves, which instead use cilia, waving filaments that bring minute organisms to the mouth.

<span class="mw-page-title-main">Nudibranch</span> Order of gastropods

Nudibranchs belong to the order Nudibranchia, a group of soft-bodied marine gastropod molluscs that shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to match, such as "clown", "marigold", "splendid", "dancer", "dragon", and "sea rabbit". Currently, about 3,000 valid species of nudibranchs are known.

<span class="mw-page-title-main">Sea slug</span> Group of marine gastropods

Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails that, over evolutionary time, have either entirely lost their shells or have seemingly lost their shells due to having a significantly reduced or internal shell. The name "sea slug" is often applied to nudibranchs and a paraphyletic set of other marine gastropods without apparent shells.

<span class="mw-page-title-main">Opisthobranchia</span> Informal group of gastropods

Opisthobranchs is a now informal name for a large and diverse group of specialized complex gastropods which used to be united in the subclass Opisthobranchia. That taxon is no longer considered to represent a monophyletic grouping.

<span class="mw-page-title-main">Siphon (mollusc)</span> Anatomical structure which is part of the body of some aquatic molluscs

A siphon is an anatomical structure which is part of the body of aquatic molluscs in three classes: Gastropoda, Bivalvia and Cephalopoda.

<i>Limax maximus</i> Species of slug

Limax maximus, known by the common names great grey slug and leopard slug, is a species of slug in the family Limacidae, the keeled slugs. It is among the largest keeled slugs, Limax cinereoniger being the largest.

<span class="mw-page-title-main">Limpet</span> Group of snails

Limpets are a group of aquatic snails with a conical shell shape (patelliform) and a strong, muscular foot. This general category of conical shell is known as "patelliform" (dish-shaped). Existing within the class Gastropoda, limpets are a polyphyletic group.

<i>Cornu aspersum</i> Species of edible land snail

Cornu aspersum, 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 well be the most widely known. It was classified under the name Helix aspersa for over two centuries, but the prevailing classification now places it in the genus Cornu.

<span class="mw-page-title-main">Sea snail</span> Common name for snails that normally live in saltwater

Sea snails are 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 absence of a visible shell.

<span class="mw-page-title-main">Land snail</span> Common name for many species of 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. 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.

<span class="mw-page-title-main">Slug</span> Shell-less terrestrial gastropod mollusc

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.

<span class="mw-page-title-main">Mollusca</span> Phylum of invertebrate animals

Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks. Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The number of additional fossil species is estimated between 60,000 and 100,000, and the proportion of undescribed species is very high. Many taxa remain poorly studied.

<i>Arion fasciatus</i> Species of gastropod

Arion fasciatus, also known by its common name the Orange-banded Arion, is a species of air-breathing, completely shell-less, land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae, the round-back slugs. The species was first described by Sven Nilsson in 1823.

<span class="mw-page-title-main">Digestive system of gastropods</span>

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.

<i>Crepidula adunca</i> Species of gastropod

Crepidula adunca, common name the "hooked slippersnail" is a species of sea snail or "slipper snail", a marine gastropod mollusk in the family Calyptraeidae, the slipper snails and cup-and-saucer snails.

<i>Julia exquisita</i> Species of gastropod

Julia exquisita is a small species of sea snail in the family Juliidae.

<span class="mw-page-title-main">Mating of gastropods</span>

The mating of gastropods is a vast and varied topic, because the taxonomic class Gastropoda is very large and diverse, a group comprising sea snails and sea slugs, freshwater snails and land snails and slugs. Gastropods are second only to the class Insecta in terms of total number of species. Some gastropods have separate sexes, others are hermaphroditic. Some hermaphroditic groups have simultaneous hermaphroditism, whereas some sequential hermaphroditism. In addition, numerous very different mating strategies are used within different taxa.

Laonidae is a family of small marine snails belonging to the superfamily Philinoidea, though Laonidae and Philinoidea are genetically distinct. They are monophyletic, meaning they are developed from a single ancestor. Laonidae also has the synonymised name Laoninae, which is largely unaccepted in the modern day scientific community. The name Laoninae is introduced by Alice Pruvot-Fol who proposes it as the subfamily to the genea Loana, A.Adams 1865.

Pneumopulmonata is a superorder of heterobranch pulmonate gastropods belonging to the subterclass Tectipleura. It was defined based on results of phylogenomic studies and named by Krug et al. (2022). The superorder unites all of Panpulmonata except for Sacoglossa.

References

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  2. ↑ Jörger, Katharina M; Stöger, Isabella; Kano, Yasunori; Fukuda, Hiroshi; Knebelsberger, Thomas; Schrödl, Michael (2010). "On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia". BMC Evolutionary Biology. 10 (1): 323. Bibcode:2010BMCEE..10..323J. doi: 10.1186/1471-2148-10-323 . PMC   3087543 . PMID   20973994.
  3. ↑ "Floor tiles made of coloured snail poo by Lieske Schreuder - design". 26 November 2013. Retrieved 29 March 2018.
  4. ↑ Fredericks, Anthony D. (2010). How Long Things Live & How They Live As Long As They Do . Stackpole Books. p.  73. ISBN   9780811736220 . Retrieved 19 June 2012.
  5. ↑ "New snail species are world's smallest, tinier than grains of sand". National Geographic. 2 Feb 2022. Archived from the original on 30 Aug 2022. Retrieved 16 Oct 2024.
  6. ↑ "Largest Snail". Guinness World Records. Retrieved 17 December 2016.
  7. ↑ Pegler, Sam (2018). "Snail locomotion" (PDF). Woods Hole Oceanographic Institution. Retrieved October 7, 2024.
  8. ↑ "Gastropod - Shell Structure, Anatomy, Diversity | Britannica". www.britannica.com. 2024-09-03. Retrieved 2024-10-07.
  9. ↑ Rodriguez, Cristian; Prieto, Guido I.; Vega, Israel A.; Castro-Vazquez, Alfredo (2021-04-14). "Morphological grounds for the obligate aerial respiration of an aquatic snail: functional and evolutionary perspectives". PeerJ. 9: e10763. doi: 10.7717/peerj.10763 . ISSN   2167-8359. PMC   8052964 . PMID   33954023.
  10. ↑ "compound coil". dnr.illinois.gov. Retrieved 2024-10-07.
  11. ↑ Goodfriend, Glenn (1986). "Variation in Land-snail Shell form and Size and its Causes: a Review". Systematic Biology. 35 (2): 204–223. doi:10.1093/sysbio/35.2.204 – via Oxford Academic.
  12. ↑ Krings, Wencke; Faust, Taissa; Kovalev, Alexander; Neiber, Marco Thomas; Glaubrecht, Matthias; Gorb, Stanislav (July 2019). "In slow motion: radula motion pattern and forces exerted to the substrate in the land snail Cornu aspersum (Mollusca, Gastropoda) during feeding". Royal Society Open Science. 6 (7): 190222. Bibcode:2019RSOS....690222K. doi:10.1098/rsos.190222. ISSN   2054-5703. PMC   6689628 . PMID   31417728.
  13. ↑ Vortsepneva, Elena (2023). "Main patterns of radula formation and ontogeny in Gastropoda". Journal of Morphology. 284 (1): e21538. doi:10.1002/jmor.21538. PMID   36426387 – via Wiley Online Library.
  14. ↑ Krings, Wencke; Faust, Taissa; Kovalev, Alexander; Neiber, Marco Thomas; Glaubrecht, Matthias; Gorb, Stanislav (July 2019). "In slow motion: radula motion pattern and forces exerted to the substrate in the land snail Cornu aspersum (Mollusca, Gastropoda) during feeding". Royal Society Open Science. 6 (7): 190222. Bibcode:2019RSOS....690222K. doi:10.1098/rsos.190222. ISSN   2054-5703. PMC   6689628 . PMID   31417728.
  15. ↑ Clifford, Kavan T.; Gross, Liaini; Johnson, Kwame; Martin, Khalil J.; Shaheen, Nagma; Harrington, Melissa A. (2003). "Slime-trail tracking in the predatory snail, Euglandina rosea". Behavioral Neuroscience. 117 (5): 1086–1095. doi:10.1037/0735-7044.117.5.1086. ISSN   1939-0084. PMID   14570557.
  16. 1 2 "Mollusks : Carnegie Museum of Natural History". www.carnegiemnh.org. Retrieved 2024-12-04.
  17. ↑ Williamson, P.; Cameron, R. A. D. (1976). "Natural Diet of the Landsnail Cepaea Nemoralis". Oikos. 27 (3): 493–500. Bibcode:1976Oikos..27..493W. doi:10.2307/3543468. ISSN   0030-1299. JSTOR   3543468.
  18. ↑ Speiser, Bernhard; Rowell-Rahier, Martine (1991). "Effects of Food Availability, Nutritional Value, and Alkaloids on Food Choice in the Generalist Herbivore Arianta arbustorum (Gastropoda: Helicidae)". Oikos. 62 (3): 306–318. Bibcode:1991Oikos..62..306S. doi:10.2307/3545495. ISSN   0030-1299. JSTOR   3545495.
  19. ↑ Davies, Mark S.; Hawkins, S. J. (1998-01-01), Blaxter, J. H. S.; Southward, A. J.; Tyler, P. A. (eds.), Mucus from Marine Molluscs, Advances in Marine Biology, vol. 34, Academic Press, pp. 1–71, doi:10.1016/s0065-2881(08)60210-2, ISBN   978-0-12-026134-5 , retrieved 2024-12-04
  20. ↑ "Slug vs Snail - Difference and Comparison - Diffen" . Retrieved 29 March 2018.
  21. ↑ 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.
  22. ↑ Sanders, April. "Do Egg Shells Help Stop Snails From Eating Plants?" Home Guides | SF Gate. Accessed 01 July 2019.
  23. ↑ Ziderman, I. I. (1986). "Purple dye made from shellfish in antiquity". Review of Progress in Coloration. 16: 46–52. doi:10.1111/j.1478-4408.1986.tb03743.x. ISSN   1472-3581.
  24. ↑ Biggam, Carole P. (March 2006). "Whelks and purple dye in Anglo-Saxon England" (PDF). The Archeo+Malacology Group Newsletter (9).
  25. ↑ Moorey, Peter (1999). Ancient Mesopotamian Materials and Industries: The Archaeological Evidence . Winona Lake, Indiana: Eisenbrauns. p.  138. ISBN   978-1-57506-042-2.
  26. ↑ Nuttall, Zelia (1909). "A Curious Survival in Mexico of the Use of the Purpura Shell-fish for Dyeing". In Boas, Franz (ed.). Putnam Anniversary Volume. Vol. Anthropological Essays Presented to Fredrick Ward Putnam in Honor of his Seventieth Birthday, by his Friends and Associates. New York: G. E. Stechert & Co. pp. 368–384. LCCN   10011191.
  27. ↑ "BBC Radio 3 – Slow Radio – Seven of the world's most famous snails". BBC. Retrieved 2020-02-14.
  28. ↑ "The height of slow-food, France serves snail caviar". Reuters. 20 December 2007.
  29. ↑ Chambers, Robert (1858). Domestic annals of Scotland, from the reformation to the revolution. W. & R. Chambers. (Also quoted here.
  30. 1 2 de Vries, Ad (1976). Dictionary of Symbols and Imagery. Amsterdam: North-Holland Publishing Company. p.  430. ISBN   978-0-7204-8021-4.
  31. ↑ Tresidder, Jack (2006). Symbols and Their Meanings. New York: Barnes & Noble. p. 41. ISBN   978-0-7607-8164-7.
  32. ↑ Susan Milbrath, Star Gods of the Maya: Astronomy in Art, Folklore, and Calendars, University of Texas Press, 01/01/2010
  33. ↑ Cooper, J. C. (1992). Symbolic and Mythological Animals. London: Aquarian Press. p. 213. ISBN   978-1-85538-118-6.
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