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The black slug (also known as black arion, European black slug, or large black slug), ''Arion ater'', is a large terrestrial
gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...
mollusk in the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Arionidae, the round back slugs. Many land slugs lack external shells, having a vestigial shell. Most slugs retain a remnant of their shell, which is usually internalized, unlike other terrestrial mollusks (such as
snail A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial molluscs, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gas ...
s) which have external shells. Without such shells, slugs produce mucus, that may also contain toxins—to deter predators. Terrestrial slugs produce two other forms of mucus that facilitate locomotion and prevent death from drying. Such mollusks are
hermaphroditic A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...
. Slugs most often function as
decomposer Decomposers are organisms that break down dead organisms and release the nutrients from the dead matter into the environment around them. Decomposition relies on chemical processes similar to digestion in animals; in fact, many sources use the word ...
s but are also often
omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...
s. ''Arion ater'' is one such slug, decomposing organic matter, preying on other organisms, and consuming vegetative matter including agricultural crops. Native to Europe, the black slug is an invasive species in Australia, Canada (British Columbia, Newfoundland, Quebec), and the United States (Pacific Northwest, Alaska).


Description

''Arion ater'' varies from , reaching maturity at about and moves at a speed of up to Stroud, Angela. "Arion Ater." Animal Diversity Web. 2000. http://animaldiversity.org/site/accounts/information/Arion_ater.html . The black slug is generally deep black, with some adults being brown or even white. Generally, pigmentation darkens directly with increasing latitude. Young specimens tend to be brown or ivory whitish, turning to grey before becoming characteristically black at maturity.''Arion ater''
o
Animal diversity web
/ref> Rust-brown individuals are arguably classified as a separate species ''Arion rufus'' ( Red Slug). The two can only be distinguished by dissecting the reproductive anatomy. The foot-fringe is black, the
tubercle In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projectio ...
s are large and elongate, and the sole is blackish grey. The atrium and vagina (genitalia) are considerably narrower than is the spermatheca (organ for storing sperm). The oviduct is narrow while the spermatheca is spherical.Schultes, F. "AnimalBase :: Arion lusitanicus Species Homepage." AnimalBase :: Arion lusitanicus Species Homepage. 2013. http://www.animalbase.uni-goettingen.de/zooweb/servlet/AnimalBase/home/species?id=1811 . The black slug is omnivorous, and its diet includes fungi, carrion, earthworms, leaves, stems, dead plant material and dung. The food is shredded into tiny pieces by the radula and is then digested by enzymes. Like other terrestrial slugs, the black slug is a hermaphrodite, preferring to find a mate—often several—but can self-fertilize. After mating, the black slug seeks a dark, moist environment such as beneath mosses—occasionally within topsoil—to lay its eggs about in diameter. Between August and October, an individual slug lays up to 150 eggs every one to three weeks—clutches diminishing to 20 eggs late in the season. Juveniles hatch after at least twenty-seven days, hatching later under cold temperatures. Maturation takes up to nine months, enabling mating in early summer. Black slugs die shortly after laying its last clutch, rarely surviving into a second year. The ovotestis (gonad or hermaphrodite gland) produces gametes at the proximal end of the reproductive system. The hermaphrodite duct runs forward, connecting to the albumen gland and the common duct (spermoviduct). The male and female gametes separate before entering the common duct. The male portion of the reproductive tract contains the vas deferens and the epiphallus. ''Arion'' slugs lack a penis. The vas deferens connects the spermoviduct to the epiphallus. The epiphallus then opens to the genital atrium. The spermathecal duct (bursa copulatrix duct) is a sac for storing spermatozoa and also enters the atrium. The female portion contains the oviduct, transferring eggs from the common duct to the atrium. The atrium is further subdivided into an upper and lower atrium. A stimulating organ (ligula) can also be found in the atrium. Finally, the atrium opens through the genital pore. The genital pore is located on the animal slightly behind and below the right upper tentacle on the head. Like other members of the family Arionidae, the black slug has a pneumostome (breathing hole) on the right side of its mantle through which it breathes. This mantle is the part in snails that secretes a shell, but in the black slug, the mantle contains a resilient protective structure of
calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...
granules. ''Arion ater'' produces three forms of mucus. The first two aid the animal in locomotion, with a thinner mucus coating the animal laterally, and a thicker, more viscous mucus secreted along the length of the slug. This combination facilitates wave like contractions of the foot that propel the animal forward. The third type of mucus is a vile-tasting substance which helps deter predation. All three forms of mucus help protect the slug from dehydration, as well as to locate and identify other slugs to mate with, or even prey upon. File:Arion ater white.png, White variant of the black slug ''Arion ater'' File:Brown slug.JPG, Brown variant of ''Arion ater'' File:Brown_Arion_Ater.jpg, Brown ''Arion ater'' File:TaylorMonographArionAter.jpg, Colour variants of ''Arion ater'' File:Black (Chocolate) Slug found in Tilleda, Germany.jpg, Brown variant found in Tilleda,
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
Babosa común (Arion ater), Hartelholz, Múnich, Alemania, 2020-06-22, DD 46-59 FS.jpg, Detail of the skin


Distribution

This species is found in northern Europe (including Great Britain and Ireland), Canada, the Pacific Northwest, and most recently in Australia and some Caribbean countries: * Great Britain: often found in habitats more wooded and less human-dense than those in which ''A. rufus'' occurs * Maladeta Mountains, Spain: often an agricultural pest * Ireland, Italy, Germany, Scandinavia, and Gerês, Portugal * Canada nvasive first document in 1941, established pest by 1960 ** British Columbia ** Newfoundland ** Quebec (specifically on Mont Bellevue in
Sherbrooke Sherbrooke ( , ) is a city in southern Quebec, Canada. It is at the confluence of the Saint-François River, Saint-François and Magog River, Magog rivers in the heart of the Estrie administrative region. Sherbrooke is also the name of a territ ...
) * United States nvasive Within its native habitats, this species functions as a decomposer/consumer and often becomes an agricultural pest. This species is well-established in Washington and Oregon, and it is considered to represent a potentially serious threat as a pest, an
invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...
which could negatively affect agriculture, natural ecosystems, human health or commerce. Therefore, it has been suggested that this species be given top national
quarantine A quarantine is a restriction on the movement of people, animals, and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have bee ...
significance in the USA. * Australia nvasive The Museum Victoria reports the black slug to have been first documented in Australia in 2001 with multiple reports of these slugs in cultivated gardens and farms since, but as of 2009, the species was still not considered to be an established species in Australia."Black Slugs." ''Museum Victoria''. 05 Apr. 2009. Web.


Ecology

The black slug is mainly nocturnal and avoids exposure to sunlight, although in introduced areas, it has been observed to be active all parts of the day and night. It is
omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...
, eating
carrion Carrion (), also known as a carcass, is the decaying flesh of dead animals. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...
,
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
, animal feces,
algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...
,
lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...
, and
vegetation Vegetation is an assemblage of plants and the ground cover they provide. It is a general term, without specific reference to particular Taxon, taxa, life forms, structure, Spatial ecology, spatial extent, or any other specific Botany, botanic ...
(living or decaying). These slugs prefer to eat on cloudy days or at night when temperatures are above 10 degrees Celsius. Mucus-production necessitates moist habitats, such as among leaf-litter, mosses, or fallen trees. Consequently, the black slug becomes most active after rainfall. A 1976 study compared black slug assimilation rates to that of similar slugs in the UK. The study determined the black slug feeds at similar rates to other European slugs (in terms of biomass), suggesting the black slug is an equally important decomposer/consumer in forest systems. The study theorized these high assimilation rates might result from abundant enzymes in slug digestive systems: amylase, invertase,
cellulase Cellulase (; systematic name 4-β-D-glucan 4-glucanohydrolase) is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides: : Endo ...
, xylanase, and chitinase. The last might be especially indicative of how these slugs can consume large quantities of fungi such as ''
Armillaria mellea ''Armillaria mellea'', commonly known as honey fungus, is an edible basidiomycete fungus in the genus ''Armillaria''. It is a plant pathogen and part of a cryptic species complex of closely related and Morphology (biology), morphologically simila ...
''.Jennings, T. J., and J. P. Barkham. "Quantitative Study of Feeding in Woodland by the Slug Arion Ater." ''Oikos'' 27.1 (1976): 168. Web. Microbiota within black slug digestive systems produce these enzymes—such as the bacteria that produce cellulose—enabling the slugs to break down lignocellulose. A recent study further explored ''Arion ater''’s
gut microbiome Gut microbiota, gut microbiome, or gut flora are the microorganisms, including bacteria, archaea, fungi, and viruses, that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the g ...
and discovered the black slug to have far more bacteria within its gut than did neighboring, northern European insects, including members of the orders ''
Coleoptera Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
,
Isoptera Termites are a group of detritophagous eusocial cockroaches which consume a variety of decaying plant material, generally in the form of wood, leaf litter, and soil humus. They are distinguished by their moniliform antennae and the soft-bo ...
,
Orthoptera Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – gras ...
'', and ''
Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advance ...
''. This study learned the black slug’s gut microbiome to be functional at a wide range of temperatures and pH levels, and its results suggest that the mycobacterial culture may be uniform throughout the black slug’s gut and that ''
Gammaproteobacteria ''Gammaproteobacteria'' is a class of bacteria in the phylum ''Pseudomonadota'' (synonym ''Proteobacteria''). It contains about 250 genera, which makes it the most genus-rich taxon of the Prokaryotes. Several medically, ecologically, and scienti ...
'' composes most of this culture. This study contrasted its results to studies of North American black slugs that presented higher levels of cellulolytic activity at a narrower pH range. In summary, ''Arion ater'' can digest diverse food material such as cellulose because gut bacteria produce digestive enzymes.Joynson, Ryan, Arvind Swamy, Paz Aranega Bou, Ambre Chapuis, and Natalie Ferry. "Characterization of Cellulolytic Activity in the Gut of the Terrestrial Land Slug Arion Ater: Biochemical Identification of Targets for Intensive Study." ''Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology'' 177–178 (2014): 29–35. Web. As decomposers/consumers, slugs engage an important niche, contributing to ecosystem health. A 2005 study looked at another ''Arion'' slug species and concluded slugs may promote plant biodiversity. This study suggested that slugs promote plant—especially
forb A forb or phorb is a herbaceous flowering plant that is not a graminoid (grass, sedge, or rush). The term is used in botany and in vegetation ecology especially in relation to grasslands and understory. Typically, these are eudicots without woo ...
—species diversity and that slugs support annual plant species’ fitness, reducing rates of successional change. Additionally, slugs help disperse seeds and spores through their waste, and slugs facilitate
nutrient cycling A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyc ...
by being an omnivorous consumer (especially a decomposer) and by leaving behind their mucus, which also facilitates decomposition. Slugs are common agricultural and horticultural pests. They consume abundant vegetative matter, especially seedlings. Additionally, many people find slugs to be unsightly. Most animals prefer not to prey upon the black slugs because of the taste of its mucus and because this mucus can make them slippery and consequently difficult to capture; however, this slug does have some natural predators, including the
hedgehog A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are 17 species of hedgehog in five genera found throughout parts of Europe, Asia, and Africa, and in New Zealand by introduction. The ...
,
badger Badgers are medium-sized short-legged omnivores in the superfamily Musteloidea. Badgers are a polyphyletic rather than a natural taxonomic grouping, being united by their squat bodies and adaptions for fossorial activity rather than by the ...
,
shrew Shrews ( family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to dif ...
,
mole Mole (or Molé) may refer to: Animals * Mole (animal) or "true mole" * Golden mole, southern African mammals * Marsupial mole Marsupial moles, the Notoryctidae family, are two species of highly specialized marsupial mammals that are found i ...
,
mouse A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...
,
frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...
,
toad Toad (also known as a hoptoad) is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands. In popular culture (folk taxonomy ...
,
snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...
, carnivorous
beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
, and some
bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
s. When picked up or touched, the black slug will contract to a hemispherical shape and begin to rock from side to side. This defensive behavior confuses predators, and is unique in the family Arionidae.


Invasive species

''Arion ater'' has been introduced to southeastern Australia and to North America, where it occurs in Newfoundland, southern British Columbia, the Pacific Northwest of the United States and some parts of Alaska. In the past two decades, its mating with the non-native (at northern latitudes) pest species ''Arion vulgaris'' (or Spanish slug) has resulted in a more resilient hybrid exhibiting increased tolerance to cold. These slugs might endanger sensitive ecosystems, especially as an
invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...
, and it is yet unclear how drastically these slugs might alter plant community compositions. The black slug is a voracious seedling predator. Terrestrial slugs are considered to be especially dangerous because they alter plant
species abundance In ecology, local abundance is the relative representation of a species in a particular ecosystem. It is usually measured as the number of individuals found per sample. The ratio of abundance of one species to one or multiple other species livin ...
, adult plant fecundity, and the production of plant defensive compounds. Black slugs are of special concern in fragmented ecosystems and areas with high shrub and tree cover. In Alaska, the black slug threatens seedling populations of lilies and orchids after already having diminished sensitive populations of deltoid
balsamroot ''Balsamorhiza'' is a genus of plants in the family Asteraceae known commonly as balsamroots. These are perennials with fleshy taproots and caudices bearing erect stems and large, basal leaves. Atop the tall stems are showy yellow sunflower-like ...
and yellow montane violet in BC Canada. There is much debate concerning black slug effect upon plant species diversity. Slug impacts change over successional stages, and Alaska conservationists observed the black slug's impact on species diversity depends upon community composition. If a system is composed of sensitive species, the black slug will likely have a negative impact by pressuring said species. If a system presents more evenness with less sensitive species, the black slug may promote species diversity and encourage healthy succession rates. Around the 1970s, the black slug came to Alaska via nursery plants, potting soil, or among shipments containing wood pallets. The Alaska National Heritage Project published an invasive ranking for the black slug, providing a recent case study of the species as an invasive. They ranked the species based upon distribution, biological characteristics, ecological impacts, and feasibility of control. These categories were assigned points, and ''Arion ater'' received a 62/100, awarding it a qualitative score of “moderately invasive.” This report stated the black slug can often be found in disturbed soils or areas with well-irrigated soils such as lawns. Frequent sightings along roads suggest the black slug might move more easily along human traffic corridors; however, the black slug is believed to migrate little during its one-year life span. ''Arion ater''’s biology awarded it its highest risk factor. Again, the black slug is a prolific, omnivorous consumer, capable of inhabiting a wide range of conditions with high fecundity. Its effect upon local ecology received a moderate score; while the black slug puts pressure on native systems, it does not appear to catalyze entire regime shifts within the habitats where it has invaded. Greatest concern appears to be its possible pressure on early successional plants and native slugs. The black slug often feeds upon seedlings, diminishing plants’ reproductive success, but the black slug does not appear to be feeding selectively, endangering one plant species over another. And the black slug's effect on native-Alaska slugs is unknown, but the black slug might be displacing the banana slug in BC, Canada; however, such displacement might not have implications beyond those for the banana slugs. Slugs facilitate seed and spore dispersal through fecal matter. The black slug facilitates nutrient cycling by decomposing decaying and fecal matter; additionally, slug mucus left behind in the soil helps cycle nutrients, and ''Arion ater'' may merely step into this niche in place of native slugs. ''Arion ater'' has spread in Alaska in the following places: Anchorage, Cordova, Yakutat, Gustavus, Juneau, Sitka, Tenakee Springs, Ketchikan, and Kodiak Island, and in some of these areas, the black slug threatens lilies and orchids. It is unlikely complete removal can be achieved given high fecundity, but fencing and educating the public to hand pick black slugs might mitigate associated invasion risks. Conservationists within the Pacific Northwest and BC Canada are concerned about competition between ''Arion ater'' and native slugs such as the
banana slug Banana slugs (''Ariolimax'') are a genus of Pulmonata, air-breathing, terrestrial mollusc, terrestrial Gastropoda, gastropod slugs in the family Ariolimacidae.MolluscaBase eds. (2021). MolluscaBase. Ariolimax Mörch, 1859. Accessed through: World ...
(''Ariolimax californicus, A. columbianus,'' and ''A. dolichophallus''). The University of British Columbia's zoology department published a study on this interaction in 2015. They determined the two slugs to be functionally different but proposed further studies to determine whether black slugs are displacing native slugs.Rodriguez-Cabal, Mariano A., Taylor C. Gibbons, Patricia M. Schulte, M. Noelia Barrios-Garcia, and Gregory M. Crutsinger. "Comparing Functional Similarity between a Native and an Alien Slug in Temperate Rain Forests of British Columbia." ''NB NeoBiota'' 25 (2015): 1–14. Web. Their study found black slugs were more abundant and consumed a greater quantity of mushrooms than native banana slugs but could not determine reasons for differences in population sizes. They theorized the greater abundance of black slugs could be because the black slug displaced banana slugs or because the black slug might be invading areas with previously low banana slug numbers; however, there is no data for banana slug population sizes prior to the arrival of ''Arion ater''. This complicates determining whether alien slugs have a negative or negligible effect upon native slug numbers. Additionally, this study could not determine whether high fungi-consumption resulted from dietary preference or from higher concentrations of alien slugs amidst
Douglas fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is the tallest tree in the Pinaceae family. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Or ...
forests, which promote fungal growth. The study also concluded that black and banana slugs compete for under-story berries. The study demonstrated neither native nor alien slugs consume conifer or fern seedlings. It also demonstrated no significant difference between metabolic rates. However, they concluded the black slug may eat more because of its shorter life span (one compared to several years), requiring faster consumption rates to reach sexual maturity. The study demonstrated both slugs benefit ecosystems by dispersing seeds and spores. This study demonstrates the two slugs to be functionally different; however, this study proposed further research on the following to determine if black slugs are displacing banana slugs: interactions between ''Arion ater'' and fungal communities and comparative studies looking at seed dispersal rates to determine their effect on native, fruit-bearing plant communities.


Control strategies

The Garry Oak Ecosystem Recovery Team suggests the following control strategies, stating chemical controls should only be used as a last resort in protecting endangered species or critical habitat.Garry Oak Ecosystem Recovery Team. “Black Slug.” http://www.goert.ca/documents/InvFS_ariorufu.pdf . Hand collecting is most effective at
dusk Dusk occurs at the darkest stage of twilight, or at the very end of astronomical twilight after sunset and just before nightfall.''The Random House College Dictionary'', "dusk". At predusk, during early to intermediate stages of twilight, enoug ...
or
dawn Dawn is the time that marks the beginning of twilight before sunrise. It is recognized by the diffuse sky radiation, appearance of indirect sunlight being Rayleigh scattering, scattered in Earth's atmosphere, when the centre of the Sun's disc ha ...
when slugs feed most actively. Traps are also effective. Commercial traps can be used, or homemade traps can be made using beer. Fences can be used to protect small areas and can be commercial (often electrical) or easily homemade with
sawdust Sawdust (or wood dust) is a by-product or waste product of woodworking operations such as sawing, sanding, milling and routing. It is composed of very small chips of wood. These operations can be performed by woodworking machinery, portable p ...
, crushed eggshells, ground
oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but no ...
shells, soap, cinders, or
diatomaceous earth Diatomaceous earth ( ), also known as diatomite ( ), celite, or kieselguhr, is a naturally occurring, soft, siliceous rock, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder. It has a particle size ranging fr ...
. Such fences are especially effective at protecting important seedlings or home gardens. European nematodes (''Phasmarhabditis hermaphrodita'') parasitize slugs, and in European agriculture, these
nematodes The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (he ...
have been mass-produced as a biological control; however, European nematodes are neither native to North America nor commercially available. In addition to nematodes, there may be other biological control methods. Sciomyzids (marsh flies) larvae kill slugs and live in environments similar to slugs. Additionally, carabid beetles consume slug eggs. Large carabid beetles, such as '' Abax parallelepipedus'' predate slugs. The slug mite, '' Riccardoella limacum'', is known to parasitize several dozen species of mollusks, including many slugs, such as ''Agriolimax agrestis'', ''Arianta arbustrum'', ''Arion ater'', ''Arion hortensis'', ''Limax maximus'', ''Milax budapestensis'', ''Milax gagates'', and ''Milax sowerbyi''. Any use of beneficial organisms presents risks of new invaders or of disrupting native population dynamics. Again, conservation groups like the GOERT view chemical treatments as an effective last resort. For example,
metaldehyde Metaldehyde is an organic compound with the chemical formula, formula (). It is used as a pesticide against slugs and snails. It is the cyclic tetramer of acetaldehyde. Production and properties Metaldehyde is flammable, toxic if ingested in large ...
baits are very effective, but such baits are toxic to humans and native slugs. Iron phosphate baits are less toxic than metaldehyde and carbonyl baits. Iron phosphate, however, degrades rapidly and must be reapplied regularly. Alaska conservations (as previously mentioned) believe widespread watch programs to be crucial. By informing the public and by funding conservation efforts, we might be able to slow the spread of invasive slugs, preventing any possible competition between native and invasive slugs and protecting sensitive species from seedling predation.


Human use

''Arion ater'' was used as grease to lubricate wooden
axle An axle or axletree is a central shaft for a rotation, rotating wheel and axle, wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In ...
-trees or carts in Sweden. This use is documented since at least the 18th century.Svanberg I. (2006). "Blacks slugs (''Arion ater'') as grease: a case study of technical use of Gastropods in Pre-industrial Sweden". ''
Journal of Ethnobiology The ''Journal of Ethnobiology'' is a quarterly peer-reviewed academic journal covering ethnobiology. Founded in 1981, JoE is the oldest ethnobiological journal in the world. JoE is an interdisciplinary and transdisciplinary journal publishing work ...
'' 26(2): 299–309.
PDF
/ref> Black slugs are edible but rarely consumed by humans; they taste horrible, may bioaccumulate pesticides, and potentially carry French heartworm (''Angiostrongylus vasorum'') to carnivores including dogs. Researching the black slug has provided human and ecological value. For example, a 1996 study investigated the
bioaccumulation Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance faster than it can be lost or eliminated by catabolism and excretion. T ...
of mercury in black slugs and determined these slugs could be used to monitor levels of heavy metals in terrestrial systems—similar to how ecologists use aquatic mollusks.Marigómez, I., M. Soto, and M. Kortabitarte. "Tissue-level Biomarkers and Biological Effect of Mercury on Sentinel Slugs, Arion Ater." ''Arch. Environ. Contam. Toxicol. Archives of Environmental Contamination and Toxicology'' 31.1 (1996): 54–62. Web. And a 2014 study researched the black slug gut's microbiology in hopes of catalyzing other studies of cellulolytic activity that could improve biofuel technology.


References


External links


''Arion ater''
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 p ...
taxonomy,short description, distribution, biology,status (threats), images
''Arion ater''
at
Encyclopedia of Life The Encyclopedia of Life (EOL) is a free, online encyclopedia intended to document all of the 1.9 million living species known to science. It aggregates content to form "pages" for every known species. Content is compiled from existing trusted ...
images (3 pages)
"European black slug"
Alan Watson Featherstone, Species profile, Trees for Life website, accessed 23 July 2011 {{Authority control Arion (gastropod) Gastropods described in 1758 Articles containing video clips Molluscs of Europe Taxa named by Carl Linnaeus