Radix auricularia
(Linnaeus, 1758)
Common Name:
European ear snail
Synonyms and Other Names:
Lymnaea auricularia
Identification:
Radix auricularia has a width to length ratio greater than 0.75. The ear-shaped aperture, which contains no operculum, is around 5 times higher than the spire (Jokinen 1992, Mackie et al. 1980, Peckarsky et al. 1993). The shell is thin and very inflated such that the last whorl comprises 90% of its volume (Clarke 1981, Jokinen 1992, Peckarsky et al. 1993). The umbilicus is either wide or covered, the shell has a rounded and broad spire that pinches in steeply at the apex, and there are 4–5 whorls with deep sutures between them (Clarke 1981, Jokinen 1992). The color of the shell is yellow, beige or tan. The mantle is pigmented with a line of dark spots along its edge (Falniowski 1980). This species also has tentacles that are lobate, fan-shaped and wider than they are high (Jackiewicz and Buksalewicz 1998). The blood contains blue hemocyanin (Jing 1983). This species can grow to ~30 mm in height (Jokinen 1992) and 25 mm in width (Clarke 1981) as a full grown adult. However, most individuals in a population only grow to approximately half the maximum size (Clarke 1981).
Size:
can reach 35 mm in height
Native Range:
Radix auricularia is native to Europe and Asia (Jokinen 1992).
Great Lakes Nonindigenous Occurrences:
The first record of R. 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 et al. 1993). The next record is from Lincoln Park, Chicago, beside Lake Michigan in 1901 (Mills et al. 1993). Subsequently, it was found in Lake Erie and a tributary stream in 1911 and in 1948, and in Lake Ontario in 1930 (Mills et al. 1993). It is also reported from Lake Huron (Dundee 1974).
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Radix auricularia are found here.
Full list of USGS occurrences
Table last updated 4/26/2024
† Populations may not be currently present.
Ecology:
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 tends to prefer very lentic waters in lakes, bogs or slow rivers where there is a silt substrate (Clarke 1981, Jokinen 1992, Systsma et al. 2004). It has been found in environments with pH from 6.0–7.1 (Jokinen 1992, Maqbool et al. 1998). Its average thermal preference is ~19ºC, but there is great fluctuation around this mean depending on the photoperiod for the time of year (Rossetti et al. 1989). In Great Britain, the species is restricted to hard water (Adam and Lewis 1992). It can tolerate polysaprobic waters, or areas of major pollution and anoxia with high concentrations of organic matter, sulphides and bacteria (Goodnight 1973, Matuskova 1985).
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 (Adam and Lewis 1992).
It is a hermaphrodite, undergoing oogenesis in spring as daylight hours increase and spermatogenesis in late summer and early fall as daylight hours decrease (Berezkina 1981). It is iteroparous, breeding biennially (Adam and Lewis 1992). Eggs develop faster as temperature increases from 10ºC upward but fail to survive and develop at 36ºC (Salish et al. 1981).
Means of Introduction:
This snail was most likely first introduced in the late 1800s accidentally on plants that were imported to North American greenhouses. Subsequent introductions may have occurred through releases from aquaria (Mills et al. 1993). Considering its patchy distribution, it is likely that this species has been introduced multiple times (Mills et al. 1993).
Status:
Mackie et al. (1980) consider this species rare in the Great Lakes. Nevertheless, it has apparently established local populations in the Lake Ontario drainage, the Lake Erie drainage, the Lake Michigan drainage, and Lake Huron (Dundee 1974, Mills et al. 1993).
Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...
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Current research on the environmental impact of Radix auricularia in the Great Lakes is inadequate to support proper assessment.
Potential:
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 it was previously restricted to shallow bays and floodplain areas but has recently been able to colonize the rocky drop-off in the lake (Stift et al. 2004). The shells of 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 (Stift et al. 2004).
Various limnaeid snails, including R. auricularia, are vectors for a diverse range of parasites—particularly trematodes (Boray 1978). In Europe and Asia, R. auricularia is a host to such parasites as Echinoparyphium recurvatum (Sohn et al. 2002), Trichobilharzia franki (Ferte et al. 2005), T. ocellata (Zbikowska 2004), T. szidati (Kolarova et al. 1997), Clinostomum complanatum (Chung et al. 1998), Mantoscyphidia radixi (Boshko 1993), and Orientobilharzia turkestanica (Tang et al. 1990), some of which may also infect birds, mammals, and amphibians (Soldánová et al. 2010). In one German survey, 20% of captured R. auricularia were infected with trematode parasites (Soldánová et al. 2010). Another study found that average snail shell height and severity of infection with Trichobilharzia spp. are positively related (Allgoewer 1990). In its native habitat, R. auricularia preys on eggs of the parasite Ascaris suum, which survive and develop after passage through the gut and are dispersed widely due to snail activity (Asitinskaya 1975).
There is little or no evidence to support that Radix auricularia has significant socio-economic impacts in the Great Lakes.
Potential:
Radix auricularia is a documented host of a number of parasites that cause dermatitis known as “swimmer’s itch,” including Orientobilharzia turkestanica (Majoros et al. 2010, Tang et al. 1990), Trichobilharzia franki (Ferte et al. 2005), and T. ocellata (Zbikowska 2004). Cases related to R. auricularia have been documented in Europe (Zbikowska 2004).
There is little or no evidence to support that Radix auricularia has significant beneficial effects in the Great Lakes.
This species does not appear to have any significant commercial or research value.
Management:
Regulations (pertaining to the Great Lakes region)
There are no known regulations for this species.
Note: Check federal, state/provincial, and local regulations for the most up-to-date information.
Control
Specific control methods for Radix auricularia have yet to be developed.
Biological
There are no known biological control methods for this species.
Physical
There are no known physical control methods for this species.
Chemical
There are copper compounds that are sold as snailicides but they are usually not selective in the snails they kill.
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.
References
(click for full reference list)
Author:
Kipp, R.M., A.J. Benson, J. Larson, and A. Fusaro
Contributing Agencies:
Revision Date:
11/26/2019
Citation for this information:
Kipp, R.M., A.J. Benson, J. Larson, and A. Fusaro, 2024, Radix auricularia (Linnaeus, 1758): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatlakes/FactSheet.aspx?Species_ID=1012&Potential=N&Type=0&HUCNumber=DHuron, Revision Date: 11/26/2019, Access Date: 4/26/2024
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.