Bithynia tentaculata
Bithynia tentaculata
(mud bithynia, faucet snail)
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Bithynia tentaculata (Linnaeus, 1758)

Common name: mud bithynia, faucet snail

Synonyms and Other Names: faucet snail, bithynia, Bulimus tentaculatus

Taxonomy: available through www.itis.govITIS logo

Identification: The faucet snail has a shiny pale brown shell, oval in shape, with a relatively large and rounded spire consisting of 5–6 somewhat flattened whorls, no umbilicus, and a very thick lip (Clarke 1981; Jokinen 1992; Mackie et al. 1980). The aperture is less than half the height of the shell (Clarke 1981). Adult B. tentaculata possess a white, calcareous, tear-drop to oval-shaped operculum with distinct concentric rings (Clarke 1981; Jokinen 1992; Pennak 1989). The operculum of juveniles, however, is spirally marked (Jokinen 1992). The operculum is always located very close to the aperture of the shell (Jokinen 1992). The animal itself has pointed, long tentacles and a simple foot with the right cervical lobe acting as a channel for water (Jokinen 1992).

Size: shell is usually no larger than 12–15 mm; the snail is sexually mature by the time it reaches 8 mm in size (Jokinen 1992; Mackie et al. 1980; Peckarsky et al. 1993; Pennak 1989)

Native Range: Europe, from Scandinavia to Greece.

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Nonindigenous Occurrences: Great Lakes Region: Bithynia tentaculata was first recorded in Lake Michigan in 1871, but was probably introduced in 1870 (Mills et al. 1993). It spread to Lake Ontario by 1879, the Hudson River by 1892, and other tributaries and water bodies in the Finger Lakes region during the 20th century (Jokinen 1992; Mills et al. 1993). It was introduced to Lake Erie sometime before 1930 (Carr and Hiltunen 1965; Krieger 1985). This snail’s range now extends from Quebec and Wisconsin to Pennsylvania and New York (Jokinen 1992). It has been recorded from Lake Huron, but only a few individuals were found in benthic samples from Saginaw Bay in the 1980s and 1990s (Nalepa et al. 2002).

Ecology: Commonly found in freshwater ponds, shallow lakes, and canals. This species is found on the substrate in fall and winter (including gravel, sand, clay, mud or undersides of rocks) and on aquatic macrophytes (including milfoil, Myriophyllum spicatum and muskgrass, Chara spp.) in warmer months (Jokinen 1992; Pennak 1989; Vincent et al. 1981). It lives mostly in shoals, but is found at depths up to 5 m (Jokinen 1992). Bithynia tentaculata can inhabit intertidal zones in the Hudson River (Jokinen 1992). In general, the faucet snail inhabits waters with pH of 6.6–8.4, conductivity of 87–2320 μmhos/cm, Ca++ of 5–89 ppm, and Na+ of 4–291 ppm (Jokinen 1992). It can potentially survive well in water bodies with high concentrations of K+ and low concentrations of NO3- (Jokinen 1992). In the St. Lawrence River, it tends to occur in relatively unpolluted, nearshore areas (Vaillancourt and Laferriere 1983) and amongst dreissenid mussel beds (Ricciardi et al. 1997).

This species functions as both a scraper and a collector-filterer, grazing on algae on the substrate, as well as using its gills to filter suspended algae from the water column. When filter feeding, algae is sucked in, condensed, and then passed out between the right tentacle and exhalant siphon in pellet-like packages which are then eaten (Jokinen 1992). The ability to filter feed may play a role in allowing populations of the faucet snail to survive at high densities in relatively eutrophic, anthropogenically influenced water bodies (Jokinen 1992). B. tentaculata feeds selectively on food items (Brendelberger 1997). The faucet snail is known in Eurasia to feed on black fly larvae (Pavlichenko 1977).

Bithynia tentaculata is dioecious and lays its eggs on rocks, wood and shells in organized aggregates arranged in double rows, in clumps of 1–77. Egg-laying occurs from May to July when water temperature is 20ºC or higher, and sometimes a second time in October and November by females born early in the year. The density of eggs on the substrate can sometimes reach 155 clumps/m2.  Fecundity may reach up to 347 eggs and is greatest for the 2nd year class. Eggs hatch in three weeks to three months, depending on water temperature. Oocytes develop poorly at temperatures of 30–34ºC. Growth usually does not occur from September to May.  The lifespan varies regionally and can be anywhere from 17 – 39 months (Jokinen 1992; Korotneva and Dregol’skaya 1992).

In its native Eurasian habitat, the faucet snail is host to many different species of digeneans, cercariae, metacercariae, cysticercoids, and other parasites (Mattison et al. 1995; Morley et al. 2004; Toledo et al. 1998). Natural dispersal of this snail is known to occur by passive transport in birds (von Proschwitz 1997). Bithynia tentaculata is capable of detecting the presence of molluscivorous leeches through chemoreception and of closing its operculum to avoid predation (Kelly and Cory 1987).

The faucet snail has the potential to be a good biomonitor for contaminants such as Cd, Zn, and MeHg because there are good correlations between environmental concentrations and snail tissue concentrations with respect to these toxic compounds (Desy et al. 2000; Flessas et al. 2000).

Means of Introduction: Bithynia tentaculata could have been introduced to the Great Lakes basin in packaging material for crockery, through solid ballast in timber ships arriving to Lake Michigan, or by deliberate release by amateur naturalists into the Erie Canal, Mohawk River and Schuyler’s Lake (Mills et al. 1993). The most likely and most accepted explanation for its original introduction is the solid ballast vector (Jokinen 1992).

Status: The species is established in the drainages of Lake Ontario (Mills et al. 1993; Peckarsky et al. 1993), Lake Michigan (Mills et al. 1993), and Lake Erie (Krieger 1985; Mackie et al. 1980; Peckarsky et al. 1993), but not Lake Superior (Jokinen 1992). Occurrences in Lake Huron do not warrant classification as established.

Impact of Introduction:  


A) Realized: After its introduction into the Erie Canal, the faucet snail began replacing two pleurocerid species, Elimia virginica and E. livescens (Jokinen 1992). Between 1917 and 1968, the species richness of mollusks in Oneida Lake decreased by 15% as the faucet snail increased in abundance (Harman 2000). It is very probable that impacts on pleurocerids, especially Elimia spp. in Oneida Lake, have occurred because the faucet snail has higher growth rates per unit respiration than most pleurocerids due to its ability to filter feed (Tashiro and Colman 1982).  

However, after colonization by invasive zebra mussels, Dreissena polymorpha, in Oneida Lake, the density of the faucet snail decreased and overall mollusk abundance decreased even further (Harman 2000). Similar effects occurred in Lake Ontario between 1983 and 2000 due to competition with invasive dreissenid mussels (Haynes et al. 2005).      

Where the faucet snail has been observed in Lake Champlain, it generally dominates gastropod assemblages (Vermont and New York State Departments of Environmental Conservation 2000).       

This species has been known to infest municipal water supplies in abundance.

B) Potential: B. tentaculata can serve as a food item for introduced common carp Cyprinus carpio (Ricciardi 2001). It is also frequently found on introduced milfoil Myriophyllum spicatum (Vincent et al. 1981) and amongst introduced mussels (Ricciardi et al. 1997).  The snail also has the potential to be a bio-fouling organism for underwater intakes and in swimming areas (Vermont and New York State Departments of Environmental Conservation 2000).

Remarks: Bithynia was found in fossils from the Pleistocene in Glacial Lake Chicago (Jokinen 1992), but the only representative of the genus currently found in the Great Lakes is Eurasian. Bithynia tentaculata is synonymous with Bulimus tentaculatus (Jokinen 1992).

References: (click for full references)

Brendelberger, H. 1997. Contrasting feeding strategies of two freshwater gastropods, Radix peregra (Lymnaeidae) and Bithynia tentaculata (Bithynidae). Archiv für Hydrobiologie 140(1):1-21.

Burgmer, T., J. Reiss, S.A. Wickham, and H. Hillebrand. 2010. Effects of snail grazers and light on the benthic microbial food web in periphyton communities. Aquatic Microbial Ecology 61(2):163-178.

Carr, J.F., and J.K. Hiltunen. 1965. Changes in the bottom fauna of western Lake Erie from 1930 to 1961. Limnology and Oceanography 10: 551-569.

Clarke, A.H. 1981. The freshwater molluscs of Canada.  National Museum of Natural Sciences, National Museums of Canada, Ottawa, Canada. 447 pp.

Cole, R.A. 2001. Exotic parasite causes large scale mortality in American coots. U.S. Geological Survey, National Wildlife Health Center, Madison, WI. Available:

Cole, R.A., and J.C. Franson. 2006. Recurring waterbird mortalities of unusual etiologies. In: Boere, G.C., C.A. Galbraith, D.A. Stroud (Eds.). Waterbirds Around the World. The Stationery Office, Edinburgh, UK, pp. 439-440.

Desy, J.C., J.F. Archambault, B. Pinel-Alloul, J. Hubert, and P.G.C. Campbell. 2000. Relationships between total mercury in sediments and methyl mercury in the freshwater gastropod prosobranch Bithynia tentaculata in the St. Lawrence River, Quebec. Canadian Journal of Fisheries and Aquatic Sciences 57(Suppl. 1):164-173.

Flessas, C., Y. Couillard, B. Pinel-Alloul, L. St-Cyr, and P.G.C. Campbell. 2000. Metal concentrations in two freshwater gastropods (Mollusca) in the St. Lawrence River and relationships with environmental contamination. Canadian Journal of Fisheries and Aquatic Sciences 57(Suppl. 1):126-137.

Harman, W.N. 2000. Diminishing species richness of mollusks in Oneida Lake, New York State, USA. Nautilus 114(3):120-126.

Haynes, J.M., N.A. Trisch, C.M. Mayer, and R.S. Rhyne. 2005. Benthic macroinvertebrate communities in southwestern Lake Ontario following invasion of Dreissena and Echinogammarus: 1983-2000. Journal of the North American Benthological Society 24(1):148-167.

Herrmann, K.K., and R.E. Sorensen. 2009. Seasonal dynamics of two mortality-related trematodes using an introduced snail. Journal of Parasitology 95(4):823-828.

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.

Kelly, P.M., and J.S. Cory. 1987. Operculum closing as a defense against predatory leeches in four British freshwater prosobranch snails. Hydrobiologia 144(2):121-124.

Korotneva, N.V., and I.N. Dregol’skaya. 1992. Effect of the elevated temperature in the habitat of fresh water mollusk Bithynia tentaculata L. on its oogenesis. Tsitologiya 34(2):30-36.

Krieger, K.A. 1985. Snail distribution in Lake Erie, USA, Canada; the influence of anoxia in the southern central basin nearshore zone. Ohio Journal of Science 85(5):230-244.

Lawrence, J.S., P. Loegering, R. Cole, and S.D. Cordts. 2009. Scaup and coot die-off at Lake Winnibigoshish – 2008 update. Minnesota Department of Natural Resources, Section of Wildlife, Bemidji, MN. Available:

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.

Mattison, R.G., T.S. Dunn, R.E.B. Hanna, W.A. Nizami, and Q.M. Ali. 1995. Population dynamics of freshwater gastropods and epidemiology of their helminth infections with emphasis on larval parmphistomes in northern India. Journal of Helminthology 69(2):125-138.

Ménard, L., and M.E. Scott. 1987. Seasonal occurrence of Cyathocotyle bushiensis Khan, 1962 (Digenea: Cyathocotylidae) metacercariae in the intermediate host Bithynia tentaculata L. (Gastropoda Prosobranchia). Canadian Journal of Zoology 65(12):2980-2992.

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.

Mitchell, A.J. and R.A. Cole. 2008. Survival of the faucet snail after chemical disinfection, pH extremes, and heated water bath treatments. North American Journal of Fisheries Management 28:1597-1600.

Morley, N.J., M.E. Adam, and J.W. Lewis. 2004. The role of Bithynia tentaculata in the transmission of larval digeneans from a gravel pit in the Lower Thames Valley. Journal of Helminthology 78(2):129-135.

Nalepa, T.F., D.L. Fanslow, M.B. Lansing, G.A. Lang, M. Ford, G. Gostenik, and D.J. Hartson. 2002. Abundance, Biomass, and Species Composition of Benthic Macroinvertebrates Populations in Saginaw Bay, Lake Huron, 1987-1996. NOAA Great Lakes Environmental Research Laboratory and Cooperative Institute for Limnology and Ecosystem Research, Michigan, Ann Arbor. 32 pp.

Pavlichenko, V.I. 1977. The role of Hydropsyche angustipennis (Trichoptera: Hydropsychidae) larvae in destroying black flies in flowing reservoirs of the Zaporozyhe oblast, USSR. Ekologiya (Moscow) 1:104-105.

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.

Pennak, R. 1989. Fresh-water Invertebrates of the United States, 3rd ed. Protozoa to Mollusca. John Wiley & Sons, Inc., New York, New York State. 628 pp.

von Proschwitz, T. 1997. Bithynia tentaculata (L.) in Norway – a rare species on the edge of its western distribution, and some notes on the dispersal of freshwater snails. Fauna (Oslo) 50(3):102-107.

Ricciardi, A. 2001. Facilitative interactions among aquatic invaders: is an “invasional meltdown” occurring in the Great Lakes? Canadian Journal of Fisheries and Aquatic Sciences 58:2513-2525.

Ricciardi, A., F.G. Whoriskey, and J.B. Rasmussen. 1997. The role of the zebra mussel (Dreissena polymorpha) in structuring macroinvertebrate communities on hard substrata.  Canadian Journal of Fisheries and Aquatic Sciences 54: 2596–2608.

Sauer, J.S., R.A. Cole, and J.M. Nissen. 2007. Finding the exotic faucet snail (Bithynia tentaculata): Investigation of waterbird die-offs on the Upper Mississippi River National Wildlife and Fish Refuge. U.S. Geological Survey Open-File Report 2007-1065. U.S. Geological Survey, Reston, VA, 3 pp. Available:

Tashiro, J.S., and S.D. Colman. 1982. Filter-feeding in the freshwater prosobranch snail Bithynia tentaculata: bioenergetic partitioning of ingested carbon and nitrogen. American Midland Naturalist 107(1):114-132.

Toledo, R., C. Munoz-Antoli, M. Perez, and J.G. Esteban. 1998. Larval trematode infections in freshwater gastropods from the Albufera Natural Park in Spain. Journal of Helminthology 72(1):79-82.

Vaillancourt, G., and E. Lafarriere. 1983. Relationship between the quality of the environment and the benthic groupings in the littoral zone of the St. Lawrence River, Canada. Naturaliste Canadien (Quebec) 110(4):385-396.

Vermont and New York State Departments of Environmental Conservation. 2000. Lake Champlain Basin Aquatic Nuisance Species Management Plan. 65 pp.

Vincent, B., H. Rioux, and M. Harvey. 1981. Factors affecting the structure of epiphytic gastropod communities in the St. Lawrence River (Quebec, Canada). Hydrobiologia 220:57-71.

Williams, Perry.  2007. Faucet snail.  University of Minnesota.  Accessed 10/28/13.


Author: Kipp, R.M., A.J. Benson, J. Larson, and A. Fusaro

Revision Date: 6/26/2014

Citation Information:
Kipp, R.M., A.J. Benson, J. Larson, and A. Fusaro. 2017. Bithynia tentaculata. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. Revision Date: 6/26/2014

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Citation information: U.S. Geological Survey. [2017]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [2/24/2017].

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