''Mytilopsis leucophaeata'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of small

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

in the false mussel family,

Dreissenidae The Dreissenidae are a family of small freshwater aquatic bivalve molluscs, commonly called ''mussels'' although not at all closely related to true mussels. The shells of these bivalves are shaped somewhat like those of true mussels, which they ...

. It is commonly known as Conrad's false mussel or the dark false mussel.

Identification

It can look very similar to the

zebra mussel The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel, an Aquatic animal, aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally Intro ...

, with similar stripes, but it can be distinguished from it by an apophysis or projection on the inside of the shell near the umbo. Shell length ranges between <1 and 2 cm, with an average length of 1 cm.

Distribution

This species is native in the

Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...

, and spread from there via ballast water, or attached to oysters that were moved, to the

Hudson River The Hudson River, historically the North River, is a river that flows from north to south largely through eastern New York (state), New York state. It originates in the Adirondack Mountains at Henderson Lake (New York), Henderson Lake in the ...

in the 1930s, and from there to other estuaries in the eastern US including

Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The bay is located in the Mid-Atlantic (United States), Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula, including parts of the Ea ...

as well as to the

Pernambuco Pernambuco ( , , ) is a States of Brazil, state of Brazil located in the Northeast Region, Brazil, Northeast region of the country. With an estimated population of 9.5 million people as of 2024, it is the List of Brazilian states by population, ...

coast in northeastern Brazil. This species also spread via ballast water to brackish waters in Europe, including the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the ...

, the

North Sea The North Sea lies between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium, and France. A sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Se ...

, the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

and the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

as well as the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

and the

Caspian Sea The Caspian Sea is the world's largest inland body of water, described as the List of lakes by area, world's largest lake and usually referred to as a full-fledged sea. An endorheic basin, it lies between Europe and Asia: east of the Caucasus, ...

. Like the

, this species is a significant

biofouling Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, or small animals where it is not wanted on surfaces such as ship and submarine hulls, devices such as water inlets, pipework, grates, ponds, and rivers that ...

pest in many countries, especially where it has been introduced in Europe.

Habitat

''Mytilopsis leucophaeata'' is found in

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuary ...

, at salinities ranging from 0.5 psu to about 12 psu, although its upper salinity limit is usually about 5–6 psu. It attaches to hard substrates, including oyster and true mussel shells and cages for them, rocks, boats, and pilings, and also to ropes.

References

External links

* *
USGS Nonindigenous Aquatic Species web page; US range map is incomplete
{{Taxonbar, from=Q3018801 Dreissenidae Molluscs of the Atlantic Ocean Bivalves described in 1831 Taxa named by Timothy Abbott Conrad