Ariolimax columbianus are terrestrial molluscs (Phylum Mollusca, Class Gastropoda) that are closely related to snails, but lack their protective shell.
Description:
A. columbianus, commonly called banana slug, have an elongated yellowish body with numerous black spots; however, their colouring can vary from creamy white to greenish brown (Fretwell & Starzomski 2014). They are the largest slugs in North America, and the second largest slug species in the world, growing to >20 cm in length (Harper 1988). Their body has a distinctly keeled back. On the right side of their body is a hole called the pneumostome, which leads to a lung-like cavity (Harper 1988). Banana slugs sense their environment as they move through the forest using two pairs of tentacles located on their head. The upper pair of tentacles have eyes at the tip, which can sense light intensity. The lower pair contain sensory organs that are primarily used for smelling and touching the environment (Fretwell & Starzomski 2014). Movement is through contraction and relaxation of the muscular foot, which extends the full length of the animal’s underside. Mucus is produced to create traction and help the slug move. Banana slugs can reach a top speed of 16.5 cm per minute (Gordon 1994).
Ecology:
Banana slugs inhabit moist forests from southern Alaska to central California, and are often found in moist environments such as under logs and detritus (Harper 1988). They frequently return to the same shelter site after foraging and prefer to use sites inhabited by other slugs (Rollo & Wellington 1981). They are rarely found in gardens (Harper 1988). The slugs found in local gardens are likely the invasive black European slug, Arion rufus (Klinkenberg 2017).
Banana slugs are omnivores that eat plant matter, including low lying vegetation, fruits, and mushrooms as well as decaying organic matter (Fretwell & Starzomski 2014). They play an important role in the dispersal of seeds and spores of the plants and mushrooms that they eat (Gervais et al. 1998). In turn, banana slugs are preyed upon by a variety of predators, such as amphibians (e.g. salamanders), reptiles (e.g. garter snakes), birds, and small to medium-size mammals (e.g. shrews and raccoons) (Harper 1988). Banana slugs defend themselves from these predators by making their body short and fat, and secreting a lot of very thick mucus (Harper 1988). This makes the slugs difficult to ingest, and can also cause the mouth of the predator to become numb (Harper 1988). Some predators (e.g. raccoons) roll the slugs to get rid of this mucus (Harper 1988).
Banana slugs are omnivores that eat plant matter, including low lying vegetation, fruits, and mushrooms as well as decaying organic matter (Fretwell & Starzomski 2014). They play an important role in the dispersal of seeds and spores of the plants and mushrooms that they eat (Gervais et al. 1998). In turn, banana slugs are preyed upon by a variety of predators, such as amphibians (e.g. salamanders), reptiles (e.g. garter snakes), birds, and small to medium-size mammals (e.g. shrews and raccoons) (Harper 1988). Banana slugs defend themselves from these predators by making their body short and fat, and secreting a lot of very thick mucus (Harper 1988). This makes the slugs difficult to ingest, and can also cause the mouth of the predator to become numb (Harper 1988). Some predators (e.g. raccoons) roll the slugs to get rid of this mucus (Harper 1988).
Life History:
Banana slugs are hermaphrodites, having both male and female reproductive organs. They seek out partners, carry out an elaborate courtship ritual, and ultimately intertwine to exchange sperm. Once they disentangle, each slug lays up to 40 eggs under woody debris (Gordon 1994). Young slugs hatch in 3 to 8 weeks and are mature after 4 months. Adult slugs can live for up to 6 years (Gordon 1994).
References cited:
Fretwell K, Starzomski B. 2014. Pacific banana slug, Ariolimax columnianus, A. columbianum. Biodiversity of the Central Coast. [accessed 2018 Feb 1]. http://www.centralcoastbiodiversity.org/banana-slug-bull-ariolimax-columbianus.html.
Gervais JS, Traveset A, Willson MF. 1998. The potential for seed dispersal by the banana slug
(Ariolimax columbianus). American Midland Naturalist. 140(1):103–110.
Gordon DG. 1994. The Western Society of Malacologists Field guide to the slug. Seattle (WA): Sasquatch Books.
Harper AB. 1988. The banana slug. Aptos (CA): Bay Leaves Press.
Klinkenberg B, editor. 2017. Ariolimax columbianus. E-Fauna BC: Electronic Atlas of the fauna of British
Columbia. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [accessed 2018 Feb 1]. http://linnet.geog.ubc.ca/efauna/Atlas/Atlas.aspx?sciname=Ariolimax%20columbianus.
Rollo DC, Wellington WG. 1981. Environmental orientation by terrestrial Mollusca with particular reference to homing behavior. Canadian Journal of Zoology. 59(2):225–239.
Gervais JS, Traveset A, Willson MF. 1998. The potential for seed dispersal by the banana slug
(Ariolimax columbianus). American Midland Naturalist. 140(1):103–110.
Gordon DG. 1994. The Western Society of Malacologists Field guide to the slug. Seattle (WA): Sasquatch Books.
Harper AB. 1988. The banana slug. Aptos (CA): Bay Leaves Press.
Klinkenberg B, editor. 2017. Ariolimax columbianus. E-Fauna BC: Electronic Atlas of the fauna of British
Columbia. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [accessed 2018 Feb 1]. http://linnet.geog.ubc.ca/efauna/Atlas/Atlas.aspx?sciname=Ariolimax%20columbianus.
Rollo DC, Wellington WG. 1981. Environmental orientation by terrestrial Mollusca with particular reference to homing behavior. Canadian Journal of Zoology. 59(2):225–239.