Mud bithynia, faucet snail

Scientific Name: Bithynia tentaculata

Amy Benson - USGSCopyright Info

Identification: The faucet snail has a shiny pale brown shell, which is rounded near the opening and elongates into a cone shape. The shell opening is teardrop to oval-shaped and is on the right when the shell is pointed up. The animal itself has long, pointed tentacles. This species is also known as a mud bithynia snail.

Size: The shell is usually no larger than 0.5-0.6 inch (12-15 mm). The adult snail reaches 0.3 inch (8 mm) in length.

Native Range: The faucet snail is native to Europe, from Scandinavia to Greece.

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 Bithynia tentaculata are found here.

Full list of USGS occurrences

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Illinois187119741Lake Michigan
Michigan1891201622Au Gres-Rifle; Black-Macatawa; Brevoort-Millecoquins; Carp-Pine; Detroit; Kalamazoo; Kawkawlin-Pine; Keweenaw Peninsula; Lake Erie; Lake Huron; Lake Michigan; Lone Lake-Ocqueoc; Manistee; Muskegon; Ottawa-Stony; Pere Marquette-White; Pigeon-Wiscoggin; Saginaw; St. Clair; St. Marys; Sturgeon; Tacoosh-Whitefish
Minnesota200620161St. Louis
New York1879201512Great Lakes Region; Irondequoit-Ninemile; Lake Ontario; Lower Genesee; Mettawee River; Niagara; Oak Orchard-Twelvemile; Oneida; Oswego; Richelieu River; Salmon-Sandy; Seneca
Ohio188820125Ashtabula-Chagrin; Cedar-Portage; Lake Erie; Ottawa-Stony; Sandusky
Pennsylvania191120142Chautauqua-Conneaut; Lake Erie
Vermont188219742Lake Champlain; Richelieu River
Wisconsin1974201710Duck-Pensaukee; Lake Michigan; Lake Superior; Lake Winnebago; Lower Fox; Milwaukee; Peshtigo; St. Louis; Upper Fox; Wolf

Table last updated 9/30/2019

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Means of Introduction: The faucet snail was most likely introduced when water and sand were released by large timber transit ships in Lake Michigan. However, it may have arrived in vegetation used as packing material for crockery or through deliberate release by naturalists. These snails can spread when they attach to aquatic plants, boats, anchors, and other recreational gear and equipment, and may also be spread by waterfowl.

Status: This species was first found in Lake Michigan in 1871, in Lake Ontario in 1879, and in Lake Erie sometime before 1930. Breeding populations are now established in all three lakes, and the snail’s range now extends from Minnesota to Pennsylvania, New York, and Quebec.

Remarks: The faucet snail is known to feed on black fly larvae in Eurasia.

Author: Illinois-Indiana Sea Grant

Contributing Agencies:
NOAA Sea Grant GLRI Logo

Revision Date: 8/30/2012

Citation for this information:
Illinois-Indiana Sea Grant, 2019, Mud bithynia, faucet snail: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 8/30/2012, Access Date: 10/13/2019

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.