Texas Invasive Species Institute

Texas Invasive Species Institute

New Zealand mudsnail

Potamopyrgus antipodarum

Class: Gastropoda
Order: Neotaenioglossa
Family: Hydrobiidae

Potamopyrgus antipodarum

Photographer: Mike Gangloff Source: Bugwood.org Copyright: CC BY-NC 3.0

Potamopyrgus antipodarum

Photographer: U.S. Geological Survey Source: http://nas.er.usgs.gov/queries/FactSheet Copyright: CC 3.0 US


The New Zealand mudsnail, Potamopyrgus antipodarum, is a very small snail ranging from 4-6 mm in Great Lakes but up to 12 mm in New Zealand. This mudsnail has right-handed coiling (dextral coiling) with 7-8 distinct whorls. Their coloration can be quite varied, ranging from gray and dark brown to light brown.

Ecological Threat

Despite these snails being very small, they can reach densities of 5,600 per square meter, allowing them to outcompete native invertebrates and molluscs. In Snake River Idaho (the first introduction point), five native species of molluscs have been listed as endangered because of Potamopyrgus antipodarum. Their diet of diatoms, algae and detritus, and large populations can disrupt ecosystems and food web structure, by eliminating those important primary producers. They alsohave the potential to harm the food chain of the native trout, and other fish species. This snail prefers clear running waters or lakes, but has a wide salinity, turbidity, and sediment tolerance. However, it has been observed that the higher salinity waters can cause the snails to produce fewer offspring and take a longer time to develop embryos.


Potamopyrgus antipodarum feeds on animal and plant detritus, algae, sediments and diatoms. Most of the population is made up of asexually reproducing females, which are actually born with developing embryos in their reproductive system! After about 3-6 months they are able to produce the embryos. One female may carry 10-90 embryos. Both the high fecundity and quick sexual maturity allow these snails to spawn and spread quickly. 


How the mudsnail arrived is unknown, but may have come from ballast water or water in live game fish imports. It was first discovered in Snake River in Idaho in 1987. By 1991 it was found in Lake Ontario, Michigan and reached Yellowstone National Park in 1996. Potamopyrgus antipodarum then spread through California, Oregon, Washington, Arizona, Utah, and throughout Lake Ontario on the New York and Canada borders. In 2004, the mudsnails were found in a Colorado creek and in Illinois by 2006.

Native Origin

New Zealand

Current Location

U.S. Habitat: Freshwater streams, rivers, ponds and lakes.

U.S. Present: AZ, CA, CO, IA, ID, IL, IN, MN, MT, NV, NY, OH, OR, PA, UT, WA, WI, and WY

For a map provided by the U.S. Geological survey click here


Much like other aquatic noxious weeds and pests, maintain clean boating and fishing equipment is crucial to stop the spread. These small snail make for inconspicuous hitchhikers, allowing them to spread quicker than they would without human interaction. BE SURE TO FULLY CLEAN YOUR BOATS AND HULLS TO PREVENT FURTHER SPREAD!

Physical control of this small snail is possible in isolated water bodies such as, ponds and fish hatcheries. Researchers are looking into biological controls, with some efficacy coming from a trematode parasite from New Zealand. Also, the parasite has shown to be very specific in host infection, only harming the New Zealand mudsnail.

For best results, an integrated management plan should be implemented. This includes preventative measures, public awareness and education, monitoring, and a mixture of physical and chemical treatments, if possible.


Broekhuizen, N., S. Parkyn, and D. Miller. 2001. Fine sediment effects on feeding and growth in the invertebrate grazer Potamopyrgus antipodarum (Gastropoda, Hydrobiidae) and Deleatidium sp. (Ephemeroptera, Letpophlebiidae). Hydrobiologia 457(1–3):125–132.

Hall, R.O., Jr., J.L. Tank, and M.F. Dybdahl. 2003. Exotic snails dominate nitrogen and carbon cycling in a highly productive stream. Frontiers in Ecology and the Environment 1(8):407–411.

Levri, E.P., A.A. Kelly, and E. Love. 2007. The invasive New Zealand mud snail (Potamopyrgus antipodarum) in Lake Erie. Journal of Great Lakes Research 33: 1–6.

Zaranko, D.T., D.G. Farara, and F.G. Thompson. 1997. Another exotic mollusk in the Laurentian Great Lakes: the New Zealand native Potamopyrgus antipodarum (Gray 1843) (Gastropoda, Hydrobiidae).

Internet Sources





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