There are a number of invasive snails that are found in North America and threaten native, freshwater ecosystems. Mystery snails are considered a high risk invasive species for B.C. and the goal is to continue preventing any further introductions or establishment of these snail species in B.C. These snails are known as Mystery snails because females give birth to live offspring, so young, fully developed snails “mysteriously” appear.
Oriental mystery snail
NOTE: This snail species is still often referred to as the Chinese mystery snail.
The Oriental mystery snail (Cipangopaludin chinensis) is native to eastern Russia and southeast Asia. They were brought to North America during the 1800’s. In B.C. they have been reported on southern Vancouver Island and near Mission. Elsewhere in North America, they can be found in McGregor Lake in Alberta (since 2019), in the Great Lakes region and several U.S. states.
The shells of Oriental mystery snails are olive-green to brown in colour and cone-shaped with 6-7 whorls. They are currently the largest snail that exists in B.C. The Oriental mystery snail does not have any stripes on their shell. Females will live up to 5 years and produce more than 169 live offspring during their lifespan.
Banded mystery snail
The Banded mystery snail (Viviparus georgianus) is native to the east-central United States (between Gulf of Mexico, Mississippi River and Illinois). They are not known to exist in B.C., however, they are found in eastern Canada around the Great Lakes and St. Lawrence River in Ontario and Quebec.
The shells of the Banded mystery snail are yellow to brown in colour and cone-shaped. As their name suggests, they have red-brown bands around the shell. They don’t grow larger than 4 cm.
Like most snails, they are typically found in areas with slow-moving water, like sheltered areas of lakes, rivers and ponds. And they also prefer soft substrates, like mud, silt or sand (as opposed to rocky bottoms). They feed on the small organic particles (e.g. algae, diatoms, other plant matter) found in these soft substrates. Although they are most frequently found near a water source, they can survive up to four weeks out of water!
Mystery snails are common in aquarium trade and their introduction to North America is likely due to irresponsible releases into the wild. The primary concerns about most invasive snails, like the Oriental and Banded mystery snails, are biofouling and competition with native species. They can quickly form dense populations that can clog infrastructure, like water intake pipes, or out-compete native snails for food and habitat. Because they feed primarily on algae, diatoms and fish eggs, they can have quite a large impact on food webs in wetland and aquatic ecosystems. Mass die-offs of dense populations can produce unpleasant smells, which would be very unappealing for residents and visitors alike. Unfortunately, due to their strong operculum (like a trapdoor that closes up the shell), there are currently no known effective treatment methods.
What Can We Do?
CLEAN DRAIN DRY: Clean off all plant parts, animals and mud from watercraft and equipment (e.g. boat trailers, paddles, fishing gear, waders and boots). Drain onto land all compartments and accessories that can hold water (e.g. bilge, ballast, live wells, buckets) and remove plugs before traveling. Dry the watercraft and equipment before launching into another body of water.
DON’T LET IT LOOSE: Do not purchase highly invasive species from pet stores. Never release aquarium pets or plants into the wild.
For more information:
For more information about invasive snails in Canada, visit here.
Literature and Resources
B.C. Invasive Species Alert for Chinese Mystery Snail
Minnesota Department of Natural Resources Banded Mystery Snail Factsheet
Severn Sound Banded Mystery Snail Factsheet