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''Limax maximus'' (literally, "biggest slug"), known by the
common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...
s great grey slug and leopard slug, is a species of
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 ...
in the family
Limacidae Limacidae, also known by their common name the keelback slugs, are a taxonomic family of medium-sized to very large, air-breathing land slugs, terrestrial pulmonate gastropod molluscs in the superfamily Limacoidea. Distribution The distributio ...
, the keeled slugs.Marshall, B. (2014). Limax maximus Linnaeus, 1758. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=819992 on 2014-11-06 It is among the largest keeled slugs, ''
Limax cinereoniger ''Limax cinereoniger'' is a large species of air-breathing land slug in the terrestrial pulmonate gastropod mollusk family Limacidae, the keelback slugs. This is the largest land slug species in the world.type species of the genus ''Limax''. The adult slug measures 10–20 cm (4–8 in) in length and is generally a light greyish or grey-brown with darker spots and blotches, although the coloration and exact patterning of the body of this slug species is quite variable. This species has a very unusual and distinctive mating method, where the pair of slugs use a thick thread of mucus to hang suspended in the air from a tree branch or other structure. Although native to Europe, this species has been accidentally introduced to many other parts of the world, first discovered outside its native range in Philadelphia, USA in 1867.


Description


External anatomy

The body length of the adult is 10-20  cm (4-8  in). The greater part of the body is rounded, but there is a short
keel The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
on its tail, with about 48 longitudinal rows of elongate, detached tubercles.Taylor, J. W. (7 November) 1902. part 8, pages 1-52
''Monograph of the land and freshwater Mollusca of the British Isles. Testacellidae. Limacidae. Arionidae''
Taylor Brothers, Leeds. Introductio
page XV.
page
34
52.
The body color is pale-grey, ash-colored, brownish or sometimes yellowish-white. The body is longitudinally streaked or spotted with black. The pattern of spotting is variable. The shield is always black-spotted. The sole of the foot is a uniform ash or yellowish-ash color. Tryon G. W. 1885. '' Manual of Conchology. Second series: Pulmonatabr>Volume 1
Testacellidae,
Oleacinidae Oleacinidae is a taxonomic family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade Eupulmonata (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). Anatomy In this family, the number of hap ...
,
Streptaxidae Streptaxidae is a family of carnivorous air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade Stylommatophora. Six Streptaxidae subfamilies are accepted in the 2005 taxonomy of the Gastropoda by Bouchet & Rocroi. Str ...
, Helicoidea,
Vitrinidae Vitrinidae is a family of small, air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Limacoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). MolluscaBase eds. (2021). MolluscaBase. ...
,
Limacidae Limacidae, also known by their common name the keelback slugs, are a taxonomic family of medium-sized to very large, air-breathing land slugs, terrestrial pulmonate gastropod molluscs in the superfamily Limacoidea. Distribution The distributio ...
,
Arionidae Arionidae, common name the "roundback slugs" or "round back slugs" are a taxonomic family of air-breathing land slugs, terrestrial pulmonate gastropod mollusks in the superfamily Arionoidea. Distribution The distribution of this family of slu ...
.'' 364 pp., 60 plates, page
189
190
plate 46
figure 31-35, 39; plate 49, figure 76.
The foot-fringe is pale, with a row of minute submarginal blackish tubercles. The
tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...
s are very long and slender. The reproductive pore is near the base of the right upper tentacle. Scharff R. F. (July) 1891
''The slugs of Ireland''
The Scientific Transactions of the Royal Dublin Society, volume IV., series II. Dublin, Royal Dublin Society; London, Williams & Norgate. 513-563. ''Limax maximus'' on page
page 517
521
plate LVII.
/ref> The shield is oblong, about one third of the total length of the animal. The shield is rounded in front, angular behind, and forming an angle of about 80 degrees when in motion, usually of a similar tint to the body, but boldly marbled or maculate with black, somewhat concentrically and interruptedly ridged around a sub-posterior nucleus. The
pneumostome The pneumostome or breathing pore is a respiratory opening of the external body anatomy of an air-breathing land slug or land snail. It is a part of the respiratory system of gastropods. It is an opening in the right side of the mantle of a ...
is just posterior to the midpoint of the mantle, as it is in all Limacidae. The mucus is colorless and iridescent, and not very adhesive. Although color varieties have no actual taxonomic significance, a large number of color varieties have been described, prominent among them being the varieties ''serpentinus'', ''vulgaris'', ''cellarius'' (typical), ''johnstoni'', ''maculatus'', ''ferrussaci'', ''obscurus'', ''fasciatus'' and ''rufescens'', of
Alfred Moquin-Tandon Christian Horace Benedict Alfred Moquin-Tandon (7 May 1804 – 15 April 1863) was a French naturalist and doctor. Moquin-Tandon was professor of zoology at Marseille from 1829 until 1833, when he was appointed professor of botany and director of ...
, and ''cornaliee'', of Pini.


Internal anatomy

The
shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...
of ''Limax maximus'' is reduced and internal, under the shield. The occurrence of this internal shell was known to Pliny the Elder; the shell was used by the ancient physicians for the sake of its
carbonate A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate g ...
of lime. Jeffreys J. G. 1862. ''British conchology: or, an account of the Mollusca which now inhabit the British Isles and the surrounding seas
Volume I. Land and freshwater shells
'
page 137
138.
The calcitic shell is situated beneath the hinder part of the shield, and is perceptible through the skin. The color of the shell is whitish. The shape of the shell is oblong-oval and thin, slightly convex above, and correspondingly concave beneath, with a membranous margin. The
apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex ...
or nucleus is at the posterior margin but inclined towards the left side, and forming the apophysis by which the shell is organically attached to the animal. The length of the shell is 13 mm (1/2 inch) and the width of the shell is 7 mm (1/4 inch). Shells of different Limacidae species are undiagnostic: in other words, they are not helpful for identification purpose.
Digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compon ...
: The formula of the
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 ...
is: 62-73/ × 138-157. The intestine has six convolutions and is without a
caecum The cecum or caecum is a pouch within the peritoneum that is considered to be the beginning of the large intestine. It is typically located on the right side of the body (the same side of the body as the appendix, to which it is joined). The w ...
. Of the six convolutions of the intestine, four are imbedded in the liver, and two hang freely in the body cavity. The nervous system is composed of the typical ganglia. The pedal ganglia are placed beneath the radula sac and joined together by an anterior and a posterior
commissure A commissure () is the location at which two objects abut or are joined. The term is used especially in the fields of anatomy and biology. * The most common usage of the term refers to the brain's commissures, of which there are five. Such a commi ...
. The abdominal ganglion lies a little to the right of the median line. The visceral ganglia occupy the angle between the lingual sheath and the
oesophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...
and the buccal ganglia are widely separated but joined together by a commissure nearly as thick as the ganglia themselves.
Reproductive system The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are ...
: The hermaphrodite gland (HG) is elongated and large, and is connected with spermoviduct (SO) by means of the hermaphrodite duct (HD) which takes its course through a portion of the albumen gland (AG). The spermoviduct is thick and well convoluted, and separates further down into a vas deferens or sperm-duct (VD) and an oviduct (OV). The former opens into the upper end of a very long penis (P), to which a strong retractor muscle (PRM) is attached. The lower portion of the penis unites with that of the oviduct at the genital orifice, so that there is no vestibule. The receptaculum seminis (RS) opens into the lower end of the penis near the junction of the two ducts.


Distribution


Fossil distribution

The internal shells of the different species of Limacidae are not recognizable to the species level. Therefore, the fossil distribution of ''Limax maximus'' (and other Limacidae species) is unknown. Unidentified calcitic shells of Limacidae are known from European
Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...
and Quaternary deposits.


Indigenous distribution

This species is now widely distributed around the world, but it is generally considered to be native to Europe and Mediterranean countries of Africa. Wiktor, A. 1989. Limacoidea et Zonitoidea nuda. Slimaki pomrowioksztaltne (Gastropoda: Stylommatophora). ''Fauna Poloniae'' 12,
Polska Akademia Nauk The Polish Academy of Sciences ( pl, Polska Akademia Nauk, PAN) is a Polish state-sponsored institution of higher learning. Headquartered in Warsaw, it is responsible for spearheading the development of science across the country by a society of ...
, Warszawa, 208 pp., 165-168.
Western Europe: * Great Britain - ''Limax maximus'' was first described in England in ''Animalium Angliae Tres Tractatus … Alter de Cochleis tum Terrestribus tum Fluviatilibus'' by Martin Lister in 1678. The presence of ''Limax maximus'' in England had been noted twelve years earlier in
Christopher Merret Christopher Merret FRSFRCP(16 February 1614/1615 – 19 August 1695), also spelt Merrett, was an English physician and scientist. He was the first to document the deliberate addition of sugar for the production of sparkling wine, and produced ...
's ''Pinax Rerum Naturalium Britannicarum''. * Ireland *
Benelux The Benelux Union ( nl, Benelux Unie; french: Union Benelux; lb, Benelux-Unioun), also known as simply Benelux, is a politico-economic union and formal international intergovernmental cooperation of three neighboring states in western Europe: ...
: Belgium, Netherlands, Luxembourg * France * Germany * Italy * Switzerland * Spain * Portugal Eastern Europe: * Albania * Bosnia-Hercegovina *
Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Maced ...
* Croatia * Greece * Serbia Africa: * Egypt * Algeria * Morocco


Nonindigenous distribution

The non-indigenous distribution of ''Limax maximus'' includes many countries worldwide: Europe: * all remaining countries not already listed above. Africa * Mozambique * South Africa North America: * Canada (present in 5 of 10 provinces) * Mexico * United States (present in 46 of 50 states) South America: *
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
* Brazil *
Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
* Colombia Asia: * China * Japan * India Oceania: * Australia * New Zealand


Behavior

''Limax maximus'' is
nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...
, feeding at night. It is not very active or prolific. When alarmed, or at rest, this slug merely draws its head within the shield, but does not otherwise contract its body. When irritated, it is said to expand its shield. The homing instinct is strongly developed in this species, which, after its nocturnal rambles or foraging expeditions, usually returns to the particular crevice or chink in which it has established itself. ''Limax maximus'' is capable of
associative learning Learning is the process of acquiring new understanding, knowledge, behaviors, skills, values, attitudes, and preferences. The ability to learn is possessed by humans, animals, and some machines; there is also evidence for some kind of learnin ...
, specifically
classical conditioning Classical conditioning (also known as Pavlovian or respondent conditioning) is a behavioral procedure in which a biologically potent stimulus (e.g. food) is paired with a previously neutral stimulus (e.g. a triangle). It also refers to the learn ...
, because it is capable of aversion learning and other types of learning. It can also detect deficiencies in a nutritionally incomplete diet if the
essential amino acid An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life form ...
methionine is experimentally removed from its food.


Ecology


Habitat

The slug is almost always found near human habitation — usually in lawns, gardens, cellars or in other damp areas. This species is not gregarious. It frequents gardens, damp and shady hedgerows and woods, hiding during the day beneath stones, under fallen trees, or other obscure and damp places. It does however exhibit a decided preference for the vicinity of human habitations, and readily takes up its abode in damp cellars or outbuildings. In Ireland, this predilection for human dwellings is not exhibited, and the species is restricted to woods and other similar places. It may even be met almost within a high-water mark on the seashore.


Feeding habits

''Limax maximus'' is omnivorous. It is a detrivore, cleaning up dead plants and fungi, and a
carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other so ...
known to pursue other slugs at a top speed of per minute. It is listed as a major agricultural pest by the Institute of Food and Agricultural Science Florida.


Life cycle

The eggs of this slug are deposited in a cluster, slightly attached to each other. Eggs are transparent, elastic and slightly yellowish in color. The size of the egg is 6×4.5 mm.Heller, J. Life History Strategies. In: Barker, G. M. (ed.):
The Biology of Terrestrial Molluscs
'. CABI Publishing, Oxon, UK. 2001. . 1-146, cited page: 428.
They hatch in about a month. The tiny slugs which emerge from the eggs need at least two years to reach sexual maturity. The lifespan of ''Limax maximus'' is 2.5–3 years.


Mating

The mating habits of ''Limax maximus'' are considered unusual among slugs: the
hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have s ...
slugs court, usually for hours, by circling and licking each other. After this, the slugs will climb into a tree or other high area and then, entwined together, lower themselves on a thick string of mucus, evert their white translucent mating organs ( penises) from their gonopores (openings on the right side of the head), entwine these organs, and exchange
sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, wh ...
. Both participants will later lay hundreds of eggs.


Parasites

Parasites of ''Limax maximus'' include the
nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant- parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a bro ...
''
Agfa flexilis ''Agfa flexilis'' is a species of parasitic nematodes. ''Agfa flexilis'' is the type species of the genus '' Agfa''.Morand S. & Hommay G. (1990). "Redescription de ''Agfa flexilis'' (Nematoda: Agfidae) parasite de I’appareil genital de ''Limax ...
'', which lives in its salivary glands, the nematode ''
Angiostoma limacis ''Angiostoma limacis'' is a species of parasitic nematodes. Hosts * ''Limax maximus ''Limax maximus'' (literally, "biggest slug"), known by the common names great grey slug and leopard slug, is a species of slug in the family Limacidae, ...
'', which lives in its rectum, and ''
Angiostrongylus costaricensis ''Angiostrongylus costaricensis'' is a species of parasitic nematode and is the causative agent of abdominal angiostrongyliasis in humans. It occurs in Latin America and the Caribbean. Hosts Rodents are the normal definitive hosts, especially ...
''. Like some other slugs, this species is often infested by the white parasitic slug mite '' Riccardoella limacum''. This mite swarms its body and invades its respiratory cavity. A
meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...
-causing nematode, ''
Angiostrongylus cantonensis ''Angiostrongylus cantonensis'' is a parasitic nematode (roundworm) that causes angiostrongyliasis, the most common cause of eosinophilic meningitis in Southeast Asia and the Pacific Basin. The nematode commonly resides in the pulmonary arterie ...
'', which normally infests the lungs of rats, has a larval stage which can only live in molluscs, including slugs. This nematode was once known to be a problem only in tropical areas, but it has since spread to other regions. Live slugs that are accidentally eaten with improperly cleaned vegetables, such as
lettuce Lettuce (''Lactuca sativa'') is an annual plant of the family Asteraceae. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds. Lettuce is most often used for salads, although it is also seen in other kinds of food, ...
, or slugs which have been improperly cooked, can act as vectors for the parasite.


Gallery

Limax maximus MHNT.jpg, on a forest floor in France Tigerschnegel1.jpg, on a leaf in Germany Limax maximus, Canberra, 2022-01-07.jpg,
Canberra Canberra ( ) is the capital city of Australia. Founded following the federation of the colonies of Australia as the seat of government for the new nation, it is Australia's largest inland city and the eighth-largest city overall. The ...
, Australia Limax maximus 2.jpg, A lighter specimen Limax maximus var candida.jpg, var. ''candida'' Mating_Great_Grey_Slug_4111.jpg, Mating


References

This article incorporates public domain text from references. * Spencer, H.G., Marshall, B.A. & Willan, R.C. (2009). ''Checklist of New Zealand living Mollusca.'' pp 196–219 in Gordon, D.P. (ed.) New Zealand inventory of biodiversity. Volume one. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Canterbury University Press, Christchurch.


Notes


External links


''Limax maximus''
at
Animalbase AnimalBase is a project brought to life in 2004 and is maintained by the University of Göttingen, Germany. The goal of the AnimalBase project is to digitize early zoological literature, provide copyright-free open access to zoological works, and pr ...
taxonomy,short description, distribution, biology,status (threats), images
Images of MatingGiant Garden Slug, Aliens Among Us
Virtual Exhibit of the
Virtual Museum of Canada The Digital Museums Canada (DMC; , ''MNC'') is a funding program in Canada "dedicated to online projects by the museum and heritage community," helping organizations to build digital capacity. Administered by the Canadian Museum of History (CMH) ...
.


Further reading

* * {{DEFAULTSORT:Limax Maximus Limacidae Gastropods described in 1758 Gastropods of Lord Howe Island Molluscs of Europe Taxa named by Carl Linnaeus