Faucet Snail (Bithynia tentaculata)
Species and Origin: The faucet snail is an aquatic snail native to Europe and was introduced to the Great Lakes in the 1870s. It was probably brought to North America unintentionally with the solid ballast of large timber transport ships or perhaps with vegetation used in packing crates.
Impacts: The snail is an intermediate host for three intestinal trematodes, or flukes, (Sphaeridiotrema globulus, Cyathocotyle bushiensis, Leyogonimus polyoon) that cause mortality in ducks and coots. These parasites have a complex life history and require two intermediate hosts, such as the faucet snail to develop. When waterfowl consume the infected snails, the adult trematodes attack the internal organs and cause lesions and hemorrhage. Infected birds appear lethargic and have difficulty diving and flying before eventually dying. The trematodes have contributed to the deaths of about 9,000 scaup and coots in 2007 and 2008 on Lake Winnibigoshish. Faucet snails also compete with native snails, and may clog water intake pipes and other submerged equipment. There is no evidence that other wildlife besides waterfowl, including any fish species, are adversely affected by the trematodes present in faucet snails. Anglers can eat fish from Lake Winnibigoshish without worry of the parasite. Faucet snails are not known to be co-hosts for the swimmers itch fluke.
Status: Faucet snail populations have established in Minnesota waters at Lake Winnibigoshish and in border waters of the Mississippi River near LaCrosse, Wisconsin.
Where to look: It is found on rocky shorelines, river and lake bottoms, aquatic plants, docks, and other objects placed in the water.
Regulatory classification (agency): It is proposed as a prohibited invasive species (DNR), which means import, possession, transport, and introduction into the wild will be prohibited.
Means of spread:They can spread by attaching to aquatic plants, boats, anchors, decoy anchors, other recreational gear and equipment placed in the water. Some movement by waterbirds may also spread this invasive to new waters.
How to identify it: Faucet snails are difficult for non-specialists to conclusively identify. Native snail species and young nonnative mystery snails could look similar to faucet snails. Adult faucet snails can grow up to 1/2 inch in length, but are generally smaller. They are light brown to black, with 4 to 5 whorls and a cover on the shell opening (see photo above). The shell opening is on the right when the shell pointed up (see drawing above). Specimens of suspected snails should be submitted to the DNR Invasive Species Program for identification.
How can you help?
- Inspect for and remove aquatic plants, animals, and mud from boats and equipment before transporting from one waterbody to another.
- Preferably spray with high-pressure hot (120 F) water for a couple minutes.