Invertebrates
Zebra Mussel
Dreissena polymorpha · also called zebra mussels
A single zebra mussel looks unremarkable, its small striped shell anchored firmly to a rock or pipe by sticky threads most native mussels never developed. Multiply that mussel by millions across an entire lake, and the combined filtering power is strong enough to visibly clear the water while quietly reshaping everything that depends on it.
Overview
The zebra mussel, Dreissena polymorpha, is native to the Black Sea and Caspian Sea region but has become one of the most significant invasive species across North America and parts of Western Europe. Its ability to attach to hard surfaces and filter water in massive collective volume sets it apart from most native freshwater mussels.
Small mussel, outsized impact
What makes the zebra mussel so disruptive isn’t any single individual, but the sheer scale a colony can reach once established, turning a small, unremarkable striped shellfish into one of the most economically costly invasive species in modern history.
Status
Not Evaluated — not a conservation concern in its native range, but managed as a widespread and increasing invasive species across introduced regions.
Zebra Mussel: common questions
Why is the zebra mussel considered such a problematic invasive species?
The zebra mussel is considered a major invasive species across large parts of North America, having spread rapidly after its introduction and causing extensive economic damage by clogging water intake pipes, power plant cooling systems, and other infrastructure, costs that have run into the billions of dollars in affected regions.
How does a zebra mussel stick to hard surfaces?
A zebra mussel produces sticky byssal threads that allow it to attach firmly to hard surfaces such as rocks, pipes, boat hulls, and other solid structures, an ability most native freshwater mussel species lack, which helps explain how zebra mussels colonise and clog man-made underwater infrastructure so effectively.
Can zebra mussels really change how clear a lake looks?
Yes, a dense zebra mussel population can collectively filter enormous volumes of water from a lake or river over time, an effect strong enough to significantly increase water clarity, though this same intense filtering also removes plankton that native fish and other species depend on, disrupting the broader food web.
Where did the zebra mussel originally come from?
The zebra mussel is native to the lakes and rivers of the Black Sea and Caspian Sea region of Eastern Europe and Western Asia, though it has since spread widely to numerous other regions, including large parts of North America and Western Europe, through human activities such as ballast water transport.