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Radix auricularia
Fossil range: Pleistocene–Recent
shell of Radix auricularia
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
(unranked): clade Heterobranchia
informal group Pulmonata
informal group Basommatophora
clade Hygrophila
Superfamily: Lymnaeoidea
Family: Lymnaeidae
Subfamily: Lymnaeinae
Genus: Radix
Species: R. auricularia
Binomial name
Radix auricularia
(Linnaeus, 1758)[2]

Helix Auricularia Linnaeus, 1758
Limnaea auricularia
Lymnaea auricularia

Radix auricularia, common name the big-ear radix, is a species of medium-sized freshwater snail, an aquatic pulmonate gastropod mollusk in the family Lymnaeidae.

Radix auricularia is the type species of the genus Radix.



Forms of Radix auricularia include[3]:

  • Radix auricularia f. tumida (Held, 1836)
  • Radix auricularia f. subampla (Ehrmann, 1933)

Shell description

Two shells of Radix auricularia

The shell is thin, roundly ovate and very inflated, such that the last whorl comprises 90% of its volume.[4][5][6]

The shell has a rounded and broad spire that pinches in steeply at the apex. The spire short, conic, very small compared with the body whorl.[1]

There are 4–5 whorls with deep sutures between them.[4][5] 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.[1]

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.[5][7][6] 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.[1]

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.[1]

The shell of the species can grow to ~30 mm in height[5] and 25 mm in width[4] as a full grown adult. However, most individuals in a population only grow to approximately half the maximum size.[4] The width of the shell is from 12-18 mm, and the height of the shell is 14-24 mm.[3] The shell of Radix auricularia has a width to length ratio greater than 0.75.


The body is flecked with small white spots on the back of the head and tentacles, but not on the foot.[1] The mantle is pigmented with a line of dark spots along its edge,[8] irregular spots which show through the shell. The foot is roundly elongated, 18 × 11 mm.[1]

The head is broad, auriculated.[1] This species also has tentacles that are large, flat, lobate, triangular, fan-shaped and wider than they are high.[9][1]

The blood contains blue hemocyanin.[10] The heart pulsations are slow and regular: thirty-four per minute. The animal is slow and deliberate in its movements.[1]

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.


Indigenous distribution

Radix auricularia is native to Europe and Asia.[5]

in Europe:

in Asia:

Nonindigenous distribution

Radix auricularia is an introduced species in the United States.[12]

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.[12]

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.[13] The next record is from Lincoln Park, Chicago, beside Lake Michigan in 1901.[13] Subsequently, it was found in Lake Erie and a tributary stream in 1911 and in 1948, and in Lake Ontario in 1930.[13] It is also reported from Lake Huron.[14]

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.[15] 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.[15]



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.[4][5][16]

It has been found in environments with a pH from 6.0–7.1.[5][17] Its average thermal preference is ~19°C, but there is great fluctuation around this mean, depending on the photoperiod for the time of year.[18] In Great Britain, the species is restricted to hard water.[19] It can tolerate polysaprobic waters, or areas of major pollution and anoxia with high concentrations of organic matter, sulfides and bacteria.[20][21]

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.[19]

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.[22] It is iteroparous, breeding biennially.[19] It lays its eggs in clumps of 50 to 150 eggs.[23] 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.[24]


Various lymnaeid snails, including Radix auricularia, are vectors for a diverse range of parasites, particularly trematodes.[25] About 80 % specimens of Radix auricularia from population near Wielkopolska National Park were found to contain trematodes.[26]

Radix auricularia serves as a host to numerous parasites including:

  • As first intermediate host for:
    • Clinostomum complanatum[30]
  • As a second intermediate host for:
    • Apatemon gracilis[31]
  • As an intermediate host for:

As a host for:

  • Trichobilharzia franki[34]
  • Trichobilharzia ocellata[35]
  • Trichobilharzia szidati[36]
  • Mantoscyphidia radixi[37]
  • Orientobilharzia turkestanica[38]

Some of these parasites may infect humans.

One study found that average shell height and infection severity with Trichobilharzia spp. are positively related.[39]

In its native habitat, this species preys on eggs of the parasite Ascaris suum, which survive and develop after passage through the gut, and are dispersed widely, due to the activity of the snail.[40]


This article incorporates public domain text from references [1] [12] .

  1. ^ a b c d e f g h i j k Baker F. C. (25 April) 1902. The Mollusca of the Chicago Area. Part II. Gastropoda. Bulletin No. III. of the Natural History Survey, The Chicago Academy of Sciences, 418 pp. 33 plates. Page 408-409.
  2. ^ Linnaeus, C. 1758. Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. 10th edition. Vermes. Testacea: 700-781. Holmiae. (Salvius).
  3. ^ a b Glöer, P. 2002 Die Süßwassergastropoden Nord- und Mitteleuropas. Die Tierwelt Deutschlands, ConchBooks, Hackenheim, 326 pp., ISBN 3-925919-60-0, page 213-214.
  4. ^ a b c d e Clarke, A.H. 1981. The freshwater molluscs of Canada. National Museum of Natural Sciences, National Museums of Canada, Ottawa, Canada. 447 pp.
  5. ^ a b c d e f g 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.
  6. ^ a b 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.
  7. ^ 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.
  8. ^ Falniowski, A. 1980. Pigmentation of the mantle border in Polish representatives of the subgenus Radix (Lymnaeidae, Basommatophora, Gastropoda). Basteria 44(1-4):3-8.
  9. ^ 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.
  10. ^ Jing, Z. 1983. Anatomy of the circulatory system of Radix auricularia. Acta Zoologica Sinica 29(2):133-140.
  11. ^ a b Soliman M. F.M.. Epidemiological review of human and animal fascioliasis in Egypt. J Infect Developing Countries 2008; 2(3):182-189. (PDF)
  12. ^ a b c Rebekah M. Kipp & Amy Benson. 2008. Radix auricularia. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. <> Revision Date: 2/28/2007
  13. ^ a b c 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.
  14. ^ Dundee, D. S. 1974. Catalogue of introduced mollusks of eastern North America (north of Mexico). Sterkiana 55:1-37.
  15. ^ a b 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.
  16. ^ 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.
  17. ^ 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.
  18. ^ 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.
  19. ^ a b c 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.
  20. ^ Goodnight, C. J. 1973. The use of aquatic macroinvertebrates as indicators of stream pollution. Transactions of the American Microscopical Society 92(1):1-13.
  21. ^ 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.
  22. ^ Berezkina, G. V. 1981. Seasonal changes in reproductive system of the Lymnaeidae. Zoologicheskii Zhurnal 60(7):978-983.
  23. ^ Piechocki A. 1979. Ślimaki. Fauna Słodkowodna Polski, Warszawa 1979, ISBN 83-01-01143-2.
  24. ^ 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.
  25. ^ Boray, J. C. 1978. The potential impact of exotic Lymnaea spp. on fascioliasis in Australia. Veterinary Parasitology 4(2):127-142.
  26. ^ Jackiewicz M. 2000. Błotniarki Europy (Gastropoda: Pulmonata: Lymnaeidae). Wydawnicrwo Kontekst, Poznań, ISBN 83-911523-4-0, 115 pp., page 45.
  27. ^ accessed 22 October 2008
  28. ^ Sohn, 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.
  29. ^ accessed 22 October 2008
  30. ^ Chung, 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.
  31. ^ accessed 22 October 2008
  32. ^ 22 October 2008
  33. ^ 22 October 2008
  34. ^ Ferte, H., J. Depaquit, S. Carre, I. Villena and N. Leger. 2005. Presence of Trichobilharzia szidati in Lymnaea stagnalis and T-franki in Radix auricularia in northeastern France: molecular evidence. Parasitology Research 95(2):150-154.
  35. ^ Zbikowska, E. 2004. Infection of snails with bird schistosomes and the threat of swimmer’s itch in selected Polish lakes. Parasitology Research 92(1):30-35.
  36. ^ Kolarova, L., P. Horak and J. Sitko. 1997. Cercarial dermatitis in focus: schistosomes in the Czech Republic. Helminthologia (Bratislava) 34(3):127-139.
  37. ^ Boshko, E. G. 1993. New species of ciliphoran infusoria genus Mantoscyphidia (Peritricha) from fresh water mollusks. Vestnik Zoologii 0(6):14-19.
  38. ^ Tang, C., G. Cui, Y. Qian, S. Lu and H. Lu. 1990. Structural changes in different aged worms of Orientobilharzia turkestanica of sheep in Horqin pasture of inner Mongolia and the hatching periodicity of the Miracidia. Acta Zoologica Sinica 36(4):366-376.
  39. ^ Allgoewer, R. 1990. The trematode fauna of several Freiburg dredging pools with special regard to the pathogen of cercarial dermatitis in humans. Mitteilungen des Badischen Landesvereins fuer Naturkunde und Naturschutz E V Freiburg im Breisgau 15(1):59-80.
  40. ^ Asitinskaya, S. E. 1975. The role of mollusks as benthos components in purification of water bodies from Ascaris suum eggs. Paraziologiya 9(5):432-433.

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