The Japanese mud snail is a small, slender, pointed snail from East Asia that has become invasive on the West Coast. It arrived with oysters shipped from Japan in the 1920s and now crowds mudflats in Washington, British Columbia, and California, where it pushes out the native California horn snail. It is also called the Japanese false cerith.
Appearance
- Appearance
- A tall, tapered shell up to about 1 3/8 in (3.4 cm) high, though shells over 1 in (2.5 cm) are uncommon in North America. It has 8–10 or more rounded and fine beaded ridges, and is usually gray-brown, often with a white band just below each seam.
Look-alikes
Look at the notch at the base of the shell opening: in the Japanese mud snail it forms a short, sharply twisted canal, while the California horn snail's notch is barely developed. The horn snail also has a tiny eye on the edge of its , which needs a close look.
Why they get mixed upBoth are tall, dark snails living on the same California mudflats.
Where it lives
- Typical habitats
- Mudflats
- Salt marshes
- Estuaries
- Range
- Native to the northwest Pacific, from the Kuril Islands and southern Sakhalin through Japan, Korea, and China. In North America it lives in bays and estuaries from British Columbia and Washington south into California; it was first collected at Samish Bay, Washington, in 1924.
- Preferred conditions
- Lives on soft mud in the middle of the tide zone and is rare above high tide or below low tide. It handles a wide range of saltiness and temperatures from about 28°F to 104°F (−2°C to 40°C).
Behavior
- Diet
- Grazes on plant debris and tiny algae such as diatoms on the mud surface.
- Activity
- Often rests opening-down on the mud or half-buried to keep from drying out. It can gather by the millions over large stretches of bay bottom.
Life cycle
- Reproduction
- Lays egg capsules on the mud, each holding a single embryo. The young hatch as tiny crawling snails with no swimming larval stage, which is why it spreads slowly from bay to bay.
- Time to maturity
- Starts laying eggs at about 1–2 years old.
- Lifespan
- About 6–10 years in British Columbia and California.
Name and classification
- About the name
- Populations on the West Coast were once misidentified as Batillaria zonalis, a related Asian species. Batillaria cumingii is another name often treated as the same species.
Conservation
- IUCN Red List
- NENot EvaluatedNot yet assessed
- Status
- Where it moves in, the native California horn snail declines, and efforts to eradicate the invader from California harbors have not succeeded.
- Threats
- It brought along a parasitic fluke that castrates the snail. Flukes carried by mudflat snails also pass on to seabirds.
More species to explore
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