The snails are very tiny and thus can easily go undetected as they hitch a ride to a new area. Native to New Zealand, this species was first discovered in the Snake River in Idaho and the Madison River in Montana in 1987 and has rapidly spread throughout the western United States. Potamopyrgus antipodarumar, New Zealand mud snails, are less than a quarter of an inch long and about half as wide, with five to six spiral turns or whorls.They can dominate river and lakebed habitat by achieving densities of more than 100,000 per square meter. snail157_pc.jpg Biologist Ken Davis balances several of the snails on his nail. In their native habitat they are known to reproduce sexually, they can reproduce asexually and all introduced populations are clonal. The tiny New Zealand mud snail has invaded Putah Creek near Winters on 11/25/03. One thing that's for certain is that these new invaders are here to stay. New Zealand mudsnail spread: Due to its small size, the New Zealand mudsnail can easily hitchhike on a variety of recreational and commercial equipment that comes in contact with the water and riparian zone. They hold no nutritional value for native fishes, so populations in the U.S. do not fall subject to predation. Here we present a time series of P. antipodarum invasion below Glen How has the New Zealand Mud Snail influenced evolution of the native species in Napa County, and what should be done regarding the New Zealand Mud Snail? The adult New Zealand mudsnail may easily be confused with various native and exotic species which can be similar in appearance, and all newly discovered populations should be verified by experts. The New Zealand mudsnail also survives out of water for quite some time and has no known predators or parasites in Washington state that can keep populations in check. The New Zealand mudsnail, Potamopyrgus antipodarum was first discovered in the Snake River, Idaho in the 1980's. The New Zealand mud snail (Potamopyrgus antipodarum) is spreading in the Pacific Northwest.This highly invasive species is invading new waterbodies, and may be getting help from field researchers who unwittingly carry it to new streams and rivers on their gear. New Zealand Mudsnail . But the New Zealand mud snails have laid siege to four of the five Great Lakes and are threatening to invade rivers and streams, too. only takes one New Zealand mud snail to start a new colony in a stream or river. New Zealand mud snails: A tiny gastropod is a major problem here—not there ... Also, we could investigate the parasite as a way to lower the snail populations here. Only very recently have they been detected in inland streams and rivers. 2003) and has since become a dominant component of the invertebrate assemblage. New Zealand mudsnails do have predators in their native range, but there is no evidence that predators do or could control populations. They can tolerate a wide variety of habitats including reservoirs, estuaries, rivers, and lakes. The New Zealand mud snail, Potamopyrgus antipodarum, is a very small species of freshwater snail endemic to New Zealand.It is an invasive species in many countries, including the United States, where populations of this snail can reach phenomenal densities.