A small invasive mussel introduced via ballast water from European ships. Devastating to native mussels and water quality systems.

Also called: Zebra Mussel

Native status: Non-native (Eurasia); invasive throughout US

§ Quick facts

SizeShell length 1–3 cm (0.4–1.2 in); maximum 5 cm
Weight0.5–5 g
LifespanWild 3–9 years
OrderMyoida
FamilyDreissenidae

§ Encyclopedia

The zebra mussel is a small freshwater mussel, an aquatic bivalve mollusc in the family Dreissenidae. The species originates from the lakes of southwestern Russia and southeastern Europe, but has been accidentally introduced to numerous other areas and has become an invasive species in many countries in the Northern Hemisphere. Since the 1980s, the species has invaded the Great Lakes, Hudson River, Lake Travis, Finger Lakes, Lake Bonaparte, and Lake Simcoe. The adverse effects of dreissenid mussels on freshwater systems have led to their classification as among the world's most invasive aquatic species.

Source: Wikipedia — Zebra mussel Licensed under CC BY-SA 4.0

§ Identification

Field marks. Small striped triangular freshwater mussel; characteristic zebra-like dark stripes on cream background (variable pattern); attaches to hard substrates with sticky byssal threads.

Similar species. Quagga Mussel (D. rostriformis; rounder shell, attaches less firmly). Native unionid mussels (much larger, no byssal threads).

Voice. N/A

§ Diet & behavior

Diet. Filter-feeds phytoplankton, bacteria, dissolved organic matter from the water column.

Behavior. Native to Black and Caspian seas; first detected in Great Lakes (Lake St. Clair) in 1988, likely arriving in ballast water. Has since spread to 30+ US states and caused billions of dollars of damage clogging water intakes, encrusting boat hulls, and devastating native unionid (freshwater) mussel populations. Single adult filters ~1 liter of water per day; population effects of trillions filtering simultaneously have caused dramatic increases in water clarity in Great Lakes (with cascading ecological effects). Cannot detach to move once attached by byssal threads.

§ Range

Native to Eurasia; invasive in Great Lakes

§ Habitat

Lakes and rivers with hard substrates

§ Threats

In Great Lakes: they're the threat to native species.

§ Conservation status

According to the IUCN Red List, the zebra mussel (invasive) is currently classified as Least Concern.

§ What helps

Support ballast water regulations. Don't move boats between waterways without cleaning.

Support our work More ways to help

§ Further reading

§ Sources cited

  • USGS Nonindigenous Aquatic Species
  • Great Lakes Commission
  • National Park Service Aquatic Nuisance Species