Banana slugs are North American terrestrial

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 ...

s comprising the genus ''Ariolimax''. MolluscaBase eds. (2021). MolluscaBase. Ariolimax Mörch, 1859. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=995725 on 2021-08-25 They are often bright yellow (giving rise to the "

banana A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large herbaceous flowering plants in the genus ''Musa''. In some countries, bananas used for cooking may be called "plantains", distinguis ...

" common name) although they may also be greenish, brown, tan, or white.

Species

Species within the genus ''Ariolimax'' include: ;Species brought into synonymy: * ''Ariolimax andersonii'' J. G. Cooper, 1872: synonym of Prophysaon andersonii (J.G. Cooper, 1872) (unaccepted combination) * ''Ariolimax californicus'' J.G. Cooper, 1872: synonym of ''Ariolimax californicus californicus'' J.G. Cooper, 1872 * ''Ariolimax californicus costaricensis'' Cockerell, 1890: synonym of '' Deroceras costaricensis'' (Cockerell, 1890) * ''Ariolimax hemphilli'' W. G. Binney, 1875: synonym of '' Hesperarion hemphilli'' (W.G. Binney, 1875) * ''Ariolimax niger'' J. G. Cooper, 1872: synonym of '' Hesperarion niger'' (J. G. Cooper, 1872) * ''Ariolimax steindachneri'' Babor, 1900: synonym of ''Ariolimax columbianus'' (Gould, 1851)

Description

Banana slugs are often bright yellow (giving rise to the banana nomenclature) although they may also be greenish, brown, tan, or white. The species ''Ariolimax columbianus'' sometimes has black spots that are so extensive that the animal looks almost entirely black. Individual slugs will change colors with alterations in food consumption, light exposure, and moisture levels. Color may also indicate whether a slug is healthy or injured or what age it is. The Pacific banana slug is the second-largest species of terrestrial

in the world, growing up to long, and weights of . (The largest slug species is ''

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. Banana slugs (like other gastropods and many other mollusks) have a

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 ...

, a ribbon-like anatomical structure covered in rows of microscopic teeth; the radula is used for feeding. Individuals can move at per minute. Slugs use two pairs of

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 to sense their environment. The larger, upper pair, termed "eyestalks," are used to detect light or movement. The second, lower pair are used to detect chemicals. The tentacles can retract and extend themselves to avoid damage. If a predator bites off a tentacle, the slug can grow a new one. Banana slugs have a single

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

(on the right side) which opens externally via a

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 ...

. The pneumostome lung cavity is heavily vascularized to allow gas exchange. Dehydration is a major problem for the mollusk; to combat this, banana slugs excrete a thick coating of mucus around their bodies and can also

aestivate Aestivation ( la, aestas (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a ...

. To do so, they secrete a protective layer of mucus and insulate themselves with a layer of soil and leaves. They remain inactive in this state until the environment becomes moist again. Due to their susceptibility to desiccation, they are more commonly active at night, but also appear during cool, moist days. Ariolimax columbianus 0510

The slime also contains

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

s to attract other slugs for mating. Slugs are

simultaneous hermaphrodite Simultaneous hermaphroditism is one of the two types of hermaphroditism, the other type being sequential hermaphroditism. In this form of hermaphroditism an individual has sex organs of both sexes and can produce both gamete types even in the sa ...

s, and reproduce by exchanging

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, whi ...

with their mate. They produce up to 75 translucent eggs, which are laid in a log or on leaves. Slugs mate and lay eggs throughout the year. The adults provide no further care for their eggs beyond finding a suitable hiding spot, and the eggs are abandoned as soon as the clutch is laid.

Distribution

Ariolimax columbianus The Pacific Banana Slug (Ariolimax columbianus) is a species of slug found on the Pacific coast of North America. It is the second-largest species of terrestrial slug in the world, growing up to 25 centimeters (9.8 in) long. As of 2021, it is th ...

'' is native to the forest floors along North America's Pacific coastal coniferous rainforest belt (including douglas-fir forests and redwood forests) which stretches from Southeastern

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

Santa Cruz, California Santa Cruz (Spanish for "Holy Cross") is the county seat and largest city of Santa Cruz County, in Northern California. As of the 2020 census, the city population was 62,956. Situated on the northern edge of Monterey Bay, Santa Cruz is a pop ...

. Several discontinuous populations also occur in forested slopes of the coastal and transverse mountain ranges south of Santa Cruz as far south as

Ventura County Ventura County () is a county in the southern part of the U.S. state of California. As of the 2020 census, the population was 843,843. The largest city is Oxnard, and the county seat is the city of Ventura. Ventura County comprises the Oxnar ...

, with a tiny, isolated population located in

Palomar Mountain State Park Palomar Mountain ( ; es, Monte Palomar ) is a mountain ridge in the Peninsular Ranges in northern San Diego County. It is famous as the location of the Palomar Observatory and Hale Telescope, and known for the Palomar Mountain State Park. Hist ...

within the

Palomar Mountain Range Palomar Mountain ( ; es, Monte Palomar ) is a mountain ridge in the Peninsular Ranges in northern San Diego County. It is famous as the location of the Palomar Observatory and Hale Telescope, and known for the Palomar Mountain State Park. Hist ...

San Diego County, California San Diego County (), officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the fi ...

. The Palomar Mountains have lush Sierra Nevada-like coniferous forests and black oak woodlands unlike the surrounding semiarid lands of inland San Diego County and mark the southernmost population of banana slugs. The slugs were rediscovered several years ago along Doane Creek, part of the Lower Doane Valley/Lower French Trail. This population is believed to be a

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

from the Pleistocene epoch when the climate was cooler and wetter. Small, isolated populations also occur east of the Pacific Coast such as in the inland coniferous rainforests of

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

Columbia Mountains The Columbia Mountains are a group of mountain ranges along the upper Columbia River in British Columbia, Montana, Idaho and Washington. The mountain range covers 135,952 km² (52,491 sq mi). The range is bounded by the Rocky Mountain T ...

(interior wet-belt), just west of the

Canadian Rockies The Canadian Rockies (french: Rocheuses canadiennes) or Canadian Rocky Mountains, comprising both the Alberta Rockies and the British Columbian Rockies, is the Canadian segment of the North American Rocky Mountains. It is the easternmost part ...

, and have been seen at lower elevations near creeks and damp areas of

Mount Revelstoke National Park Mount Revelstoke National Park is a national park located adjacent to the city of Revelstoke, British Columbia, Canada. The park is relatively small for a national park, covering . It is located in the Selkirk Mountains and was founded in 1914. ...

. Small populations of banana slugs have also been seen along creek and damp areas of the western slopes of the

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...

mountains to the north of

Yosemite National Park Yosemite National Park ( ) is an American national park in California, surrounded on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers an ar ...

in California. Slug densities in these outlying areas in the Columbia Mountains, Sierra Nevada Mountains, and areas south of Santa Cruz are low compared to densities in the coastal coniferous rainforest belt and are rather restricted to damp areas near creeks, ravines, and gullies. This population may also be a relic from the Pleistocene epoch.

Ecology

Banana slugs are

detritivore Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...

s, or decomposers. They process leaves, animal droppings, moss, and dead plant material, and then recycle them into soil humus. They seem to have a fondness for

mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is t ...

s, spread

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

s and

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s when they eat, and excrete a nitrogen-rich fertilizer. By consuming

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

(dead

organic matter Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...

) slugs contribute to

decomposition Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...

and the

nutrient cycles 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 cycli ...

and are an important aspect of the

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

Raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of , and a body weight of ...

garter snake Garter snake is a common name for generally harmless, small to medium-sized snakes belonging to the genus ''Thamnophis'' in the family Colubridae. Native to North and Central America, species in the genus ''Thamnophis'' can be found from the sub ...

duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form t ...

geese A goose (plural, : geese) is a bird of any of several waterfowl species in the family (biology), family Anatidae. This group comprises the genera ''Anser (bird), Anser'' (the grey geese and white geese) and ''Branta'' (the black geese). Some o ...

and

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten ...

s sometimes eat banana slugs; they roll the slugs in soil to bind the slime. Juvenile banana slugs are sometimes eaten by

moles Moles can refer to: * Moles de Xert, a mountain range in the Baix Maestrat comarca, Valencian Community, Spain * The Moles (Australian band) *The Moles, alter ego of Scottish band Simon Dupree and the Big Sound People *Abraham Moles, French engin ...

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 different fa ...

Slime

The mucus secreted by banana slugs contains chemicals that can numb the tongue of predators. This mucus can absorb up to 100 times its volume in water. Technically, this slime is neither liquid nor solid, but rather a liquid crystal substance and has many properties that interest materials engineers.

In culture

Banana slugs have been used as food by

Yurok The Yurok (Karuk language: Yurúkvaarar / Yuru Kyara - "downriver Indian; i.e. Yurok Indian") are an Indigenous people from along the Klamath River and Pacific coast, whose homelands are located in present-day California stretching from Trinidad ...

Natives of the North Coast and by German immigrants in the 19th and early 20th centuries. A yearly festival and contest is held at Russian River including slug races and a contest for recipes though, even when fed corn meal to purge them or soaked in

vinegar Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to et ...

to remove slime, the slugs' flavor is not always well regarded for the modern palate, and the most successful entries are often those in which the flavor is unnoticeable. The banana slug (specifically ''Ariolimax dolichophallus'', which is the most common banana slug on campus) is the mascot of the

University of California, Santa Cruz The University of California, Santa Cruz (UC Santa Cruz or UCSC) is a public university, public Land-grant university, land-grant research university in Santa Cruz, California. It is one of the ten campuses in the University of California syste ...

. It is common in local forests, was approved by a student vote and has won awards. One T-shirt caption was: "No known predators!"

References

Footnotes

External links

{{DEFAULTSORT:Banana Slug Ariolimacidae Endemic fauna of North America Molluscs of North America Pre-Columbian California cuisine