Radix auricularia, the big-ear radix, is a species of medium-sized freshwater snail, an aquatic pulmonate gastropod mollusk in the family Lymnaeidae.Neubauer, Thomas A.; Rosenberg, G.; Gofas, S. (2014). Radix auricularia (Linnaeus, 1758). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=248263 on 2014-11-17
Radix auricularia is the type species of the genus Radix.
Forms Forms of Radix auricularia include: Radix auricularia f. tumida (Held, 1836) Radix auricularia f. subampla (Ehrmann, 1933)
Shell description
The shell is thin, roundly ovate and very inflated, such that the last whorl comprises 90% of its volume.Clarke, A.H. 1981. The freshwater molluscs of Canada. National Museum of Natural Sciences, National Museums of Canada, Ottawa, Canada. 447 pp.
The shell has a rounded and broad spire that pinches in steeply at the apex. The spire is short and conic, and is very small compared with the body whorl.
There are 4–5 whorls with deep sutures between them. The whorls are convex, inflated, smooth and rapidly increasing. The body whorl is large and spreading. The surface is shining, lines of growth are fine, wavy, crowded, with occasionally a heavy ridge representing a rest period. Sutures are deeply impressed, channeled in some specimens.
The color of the shell is yellow, beige or tan.
The ear-shaped aperture, which contains no operculum, is around 5 times higher than the spire.Jokinen, E. 1992. The Freshwater Snails (Mollusca: Gastropoda) of New York State. The University of the State of New York, The State Education Department, The New York State Museum, Albany, New York 12230. 112 pp.Peckarsky, B. L., P. R. Fraissinet, M. A. Penton and D. J. Conklin Jr. 1993. Freshwater Macroinvertebrates of Northeastern North America. Cornell University Press, Ithaca, New York State. 442 pp.Mackie, G. L., D. S. White and T. W. Zdeba. 1980. A guide to freshwater mollusks of the Laurentian Great Lakes with special emphasis on the genus Pisidium. Environmental Research Laboratory, Office of Research and Development, U. S. Environmental Protection Agency, Duluth, Minnesota 55804. 144 pp. The aperture is very large, ovate, occupying four-fifths of the length of the entire shell. It is rounded above and flaring in old specimens below. The peristome is thin and sharp. The columella is sigmoid with a plait across the middle, which is reflected over the umbilicus.
The umbilicus is either wide or covered. Usually the umbilicus is narrow, deep, nearly closed. The epidermis is sometimes marked by light and dark lines of color, alternating.
The shell of the species can grow to ~30 mm in height and 25 mm in width as a full grown adult. However, most individuals in a population only grow to approximately half the maximum size. The width of the shell is from 12 to 18 mm, and the height of the shell is 14–24 mm.Glöer, P. 2002 Die Süßwassergastropoden Nord- und Mitteleuropas. Die Tierwelt Deutschlands, ConchBooks, Hackenheim, 326 pp., , page 213-214. The shell of Radix auricularia has a width to length ratio greater than 0.75.
Anatomy
The body is flecked with small white spots on the back of the head and tentacles, but not on the foot. The mantle is pigmented with a line of dark spots along its edge,Falniowski, A. 1980. Pigmentation of the mantle border in Polish representatives of the subgenus Radix (Lymnaeidae, Basommatophora, Gastropoda). Basteria 44(1–4):3–8. irregular spots which show through the shell. The foot is roundly elongated, 18 × 11 mm.For a detailed description of Radix auricularia, including the radula and reproductive organs, see pages 179–183 in Baker F. C. The Lymnaeidae of North and Middle America, recent and fossil (1911). The Chicago Academy of Sciences.
The head is broad, auriculated. This species also has tentacles that are large, flat, lobate, triangular, fan-shaped and wider than they are high.Jackiewicz, M. and R. Buksalewicz. 1998. Diversity in tentacle shape of European lymnaeid species (Gastropoda, pulmonata: Basommatophora). Biological Bulletin of Poznan 35(2):131–136.
The blood contains blue hemocyanin.Jing, Z. 1983. Anatomy of the circulatory system of Radix auricularia. Acta Zoologica Sinica 29(2):133–140. The heart pulsations are slow and regular: thirty-four per minute. The animal is slow and deliberate in its movements.
Distribution Indigenous distribution Radix auricularia is native to Europe and most of the Palearctic including Oman, Tibet and Vietnam.
In Europe it occurs in: Croatia Finland Germany Sweden British Isles: Great Britain and Ireland Netherlands Poland Czech Republic Horsák M., Juřičková L., Beran L., Čejka T. & Dvořák L. (2010). "Komentovaný seznam měkkýšů zjištěných ve volné přírodě České a Slovenské republiky. [Annotated list of mollusc species recorded outdoors in the Czech and Slovak Republics]". Malacologica Bohemoslovaca, Suppl. 1: 1–37. PDF. Slovakia and others
In Asia it occurs across the East Palearctic and in OmanSoliman M. F. M. (2008). "Epidemiological review of human and animal fascioliasis in Egypt". The Journal of Infection in Developing Countries 2(3): 182–189. abstract. PDF Vietnam – in northern VietnamDung B. T., Doanh P. N., The D. T., Loan H. T., Losson B. & Caron Y. (2013). "Morphological and Molecular Characterization of Lymnaeid Snails and Their Potential Role in Transmission of Fasciola spp. in Vietnam". Korean Journal of Parasitology 51(6): 657–662. . and others
Nonindigenous distribution Radix auricularia is an introduced species in the United States and New Zealand.
In the Mid-Atlantic Region it is found in the Charles River in Massachusetts, Cayuga Lake and the Hudson River in New York State, in various ponds in New Jersey, New York, and Pennsylvania, and in Lake Champlain in Vermont.
In the Great Lakes Region: The first record of Radix auricularia in North America is from the Hudson River (which is connected through the New York Canal System to Lakes Erie and Ontario) near Troy, New York, before 1869.Mills, E. L., J. H. Leach, J. T. Carlton and C. L. Secor. 1993. Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions. Journal of Great Lakes Research 19(1):1–54. The next record is from Lincoln Park, Chicago, beside Lake Michigan in 1901. Subsequently, it was found in Lake Erie and a tributary stream in 1911 and in 1948, and in Lake Ontario in 1930. It is also reported from Lake Huron.Dundee, D. S. 1974. Catalogue of introduced mollusks of eastern North America (north of Mexico). Sterkiana 55:1–37.
In 2019, Radix auricularia was recorded in Botswana and South Africa.
This species has shown a potential to adapt to new environments within large lakes, as indicated by its recent history in Lake Baikal, Russia, where this introduced species was previously restricted to shallow bays and floodplain areas, but has recently been able to colonize the rocky drop-off in the lake.Stift, M., E. Michel, T. Y. Sitnikova, E. Y. Mamonova and D. Y. Sherbakov. 2004. Palaearctic gastropod gains a foothold in the dominion of endemics: range expansion and morphological change of Lymnaea (Radix) auricularia in Lake Baikal. Hydrobiologia 513(1–3):101–108. The shells of those snails in the new habitat have a more inflated aperture and are more compact than those in the shallow zones, indicating that wave action may have selected for snails with a stronger suctioning foot in the newly colonized habitat.
Ecology Habitat This species is found in freshwater lakes, ponds, and slow-moving rivers with mud bottoms. Radix auricularia can live on boulders or vegetation in low or high-flow environments, and is capable of tolerating anoxic conditions, but it tends to prefer very lentic waters in lakes, bogs or slow rivers where there is a silt substrate.Sytsma, M. D., J. R. Cordell, J. W. Chapman and R. C. Draheim. 2004. Lower Columbia River Aquatic Nonindigenous Species Survey 2001–2004. Final Technical Report: Appendices. Prepared for the United States Coast Guard and the United States Fish and Wildlife Service. 164 pp.
It has been found in environments with a pH from 6.0 to 7.1.Maqbool, A., C. S. Hayat, T. Akhtar, A. D. Anjum and B. Hayat. 1998. Prevalence and ecology of freshwater snails in Punjab. Malaysian Applied Biology 27(1–2):69–72. Its average thermal preference is ~19 °C, but there is great fluctuation around this mean, depending on the photoperiod for the time of year.Rossetti, Y., L. Rossetti and M. Cabanac. 1989. Annual oscillation of preferred temperature in the freshwater snail Lymnaea auricularia; effect of light and temperature. Animal Behaviour 37(6):897–907. In Great Britain, the species is restricted to hard water.Adam, M. E. and J. W. Lewis. 1992. The lack of co-existence between Lymnaea peregra and Lymnaea auricularia (Gastropoda: Pulmonata). Journal of Molluscan Studies 58(2):227–228. It can tolerate polysaprobic waters, or areas of major pollution and anoxia with high concentrations of organic matter, sulfides and bacteria.Goodnight, C. J. 1973. The use of aquatic macroinvertebrates as indicators of stream pollution. Transactions of the American Microscopical Society 92(1):1–13.Matuskova, M. 1985. The significance of water mollusks in estimating the water pollution stage in the watershed of the Zitava River, Czechoslovakia. Biologia (Bratislava) 40(10):1021–1030.
Feeding habits Radix auricularia is in the family Lymnaeidae, which consists of scrapers and collector-gatherers. This species feeds on such items as detritus, Cladophora spp. (algae), and sand grains.
Life cycle Like almost all pulmonate snails, it is a hermaphrodite. It undergoes oogenesis in spring as the daylight hours increase, and spermatogenesis in late summer and early fall as the daylight hours decrease.Berezkina, G. V. 1981. Seasonal changes in reproductive system of the Lymnaeidae. Zoologicheskii Zhurnal 60(7):978–983. It is iteroparous, breeding biennially. It lays its eggs in clumps of 50 to 150 eggs.Piechocki A. 1979. Ślimaki. Fauna Słodkowodna Polski, Warszawa 1979, . Eggs develop faster as temperature increases from 10 °C upward, but the eggs fail to survive and develop when the water temperature reaches 36 °C.Salish, T., O. Al-Habbib, W. Al-Habbib, S. Al-Zako and T. Ali. 1981. The effects of constant and changing temperatures of the development of eggs of the freshwater snail Lymnaea auricularia (L.). Journal of Thermal Biology.
Parasites Various lymnaeid snails, including Radix auricularia, are vectors for a diverse range of parasites, particularly trematodes.Boray, J. C. 1978. The potential impact of exotic Lymnaea spp. on fascioliasis in Australia. Veterinary Parasitology 4(2):127–142. About 80% specimens of Radix auricularia from population near Wielkopolska National Park were found to contain trematodes.Jackiewicz M. 2000. Błotniarki Europy (Gastropoda: Pulmonata: Lymnaeidae). Wydawnicrwo Kontekst, Poznań, , 115 pp., page 45.
Radix auricularia serves as a host to numerous parasites including:
As first and as second intermediate host for: Echinostoma revolutum accessed 22 October 2008 Echinoparyphium recurvatumSohn, W.-M., H.-C. Woo and S.-J. Hong. "Tegumental ultrastructures of Echinoparyphium recurvatum according to developmental stages". Korean Journal of Parasitology 40(2): 67–73. Hypoderaeum conoideumhttp://wildlife1.wildlifeinformation.org/S/0zAPlat_Trematod/Echi_Echi_Hypoderaeum/Hypoderaeum_conoideum.htm accessed 22 October 2008 As first intermediate host for: Clinostomum complanatumChung, D.-I., H.-H. Kong and C.-Y. Joo. 1998. Radix auricularia coreana: natural snail host of Clinostomum complanatum in Korea. Korean Journal of Parasitology 36(1):1–6. As a second intermediate host for: Apatemon gracilishttp://wildlife1.wildlifeinformation.org/S/0zAPlat_Trematod/Stri_Stri_Apatemon/Apatemon_gracilis.htm accessed 22 October 2008 As an intermediate host for: