Zebra Mussels

They usually measure only the size of a fingernail, up to one inch long. Their outer shell physical characteristics consist of bands of dark and light stripes, earning their name from the zebra.

Zebra mussels are among the few freshwater mollusk species able to firmly attach to hard surfaces using byssal threads. They originated in the Eastern Europe’s Caspian Sea. Being an invasive species, they traveled in the ballast water of ships and other marine vessels into waters throughout the world.

The mollusks invaded North America by way of the Great Lakes, first being discovered in Lake St. Clair in 1988. Since that time, they have been accidentally transported to bodies of water throughout at least 32 states of the United States, most likely on the hulls and equipment of watercraft like barges and by means of the Mississippi River.

Because a female zebra mussel can lay up to 1 million eggs per year, the species easily thrives where it gains entry. Their ability to attach to hard surfaces creates problems for urban infrastructure, such as water pipes and underwater electrical utilities. Wisconsin’s utilities and agencies collectively spend hundreds of thousands of dollars annually on zebra mussel control, according to recent state reports.

5 Incredible Zebra Mussel Facts

• Up to 700,000 zebra mussels have been found living in one square meter.
• The mussel’s changes to the food web are as destructive to their habitats as toxins, nutrient pollution, and acid rain.
• Zebra mussels cause over $1 billion in economic damage and management costs each year in the United States by attaching to drinking water intake pipes, power plant equipment, and other man-made structures.
• The mollusks are moved from one water body to another by hitchhiking on barges, boats, boat trailers, seaplanes, and other watercraft.
• The mussels first entered the United States through Lake St. Clair in 1988, then were discovered in the Mississippi River by 1991.

Evolution and Origins

During the Paleozoic era, over 245 million years ago, mussels are believed to have evolved from a marine bivalve ancestor. Evidence from fossil shells suggests that mussels lived alongside dinosaurs during the Mesozoic era, also known as the Age of Dinosaurs, which spanned from 65-245 million years ago.

The zebra mussel originally comes from Eastern Europe and Western Russia. Zebra mussels were first brought into North America’s Great Lakes in 1988 due to the release of polluted ballast water from cargo ships. Following their initial introduction in the Great Lakes, human activity has enabled zebra mussels to spread into other water bodies in eastern Canada and the USA.

Classification and Scientific Name

The zebra mussel, Dreissena polymorpha, was given its scientific name by Prussian zoologist Peter Simon Pallas in 1771. The freshwater mollusk belongs to the order Myida, superfamily Dreissenoidea, and family Dreissenidae. Dreissenidae is a family of small aquatic bivalve mollusks that attach themselves to hard surfaces.

Dreissena polymorpha is partly derived from the Greek word polymorphos, meaning “of many forms.” The genus Dreissena, for which the zebra mussel is named, is one of great debate between Russian and Western scientists.

The scientists differ greatly in their styles of species identification and categorization. But 7 species are typically listed as part of Dreissena worldwide, including the zebra mussel. Besides Dreissena polymorpha, only one other species, commonly called the quagga mussel, lives in the United States.

Appearance

Zebra mussels are tiny mollusks that share physical characteristics with clams. They are named for their bands of dark and light stripes on their shells, much like the pattern of a zebra. The interior of their shell is solid white. Most of these mollusks are less than 1 inch in length, but specimens as large as 2 inches are frequently found.

Zebra mussels are a freshwater species; in fact, the only freshwater type able to attach to solid surfaces underwater. They make this attachment using byssal threads, strong, glue-like fibers on their bodies. Although their dark-light alternating shell stripes usually make the mussels easy to identify, their coloration can vary.

In the absence of clear stripes, defining physical characteristics include a dark hinge between the top and bottom shells and symmetry of the top and bottom shells. Other species of Dreissena, such as Dreissena rostriformis bugensis, have light hinges and asymmetry of the two shells.

Distribution, Population, and Habitat

Zebra mussels are destructive wherever they invade and develop a habitat. In fact, the National Oceanic and Atmospheric Administration (NOAA) reported that these mollusks cause major changes in the hydraulic flow of rivers and lakes as observed in the Detroit River. This change in river flow happens because the zebra mussels attach to the river bottom and hard surfaces in the water, forming reefs.

Their presence also leads to sharp declines in freshwater shrimp-like organisms called Diporeia. Diporeia has high fat and calorie content, making it a key part of the marine food chain in America’s lakes and rivers, as it has been since 10,000 BC.

Then, because there are fewer Diporeia to eat, the mussels also cause declining fish health. In Lake Ontario, changes in the food web after the zebra mussel invasion have affected lake trout diets and populations. Some fish species, such as walleye, have been shown to grow up to 19% slower after zebra mussel invasion due to changes in nutrient availability.

Where to Find Zebra Mussels and How to Catch Them

Zebra mussels are heavily concentrated throughout Europe and Asia, where they have lived for hundreds of years. In the 19th century, the mollusks made their way into the United Kingdom’s freshwater tributaries. In 1988, they reached America and have since made their way into at least 32 U.S. states as of 2025, and are reproducing by the millions. According to the US Geological Survey’s known facts, zebra mussels are now present in most states adjacent to the Great Lakes and the Mississippi River as of 2025.

They are also in California, Colorado, Nebraska, South Dakota, Kansas, Pennsylvania, Virginia, West Virginia, and Oklahoma, states with rivers that connect to the Mississippi River. Because of their rapid invasion, high numbers, survival rates, and few predators, the IUCN Red List classifies the zebra mussel population as being of least concern.

Zebra mussels prefer slightly alkaline water that ranges in temperature from 68 degrees to 77 degrees Fahrenheit at 2 meters to 12 meters deep. They do not like shallower water because the waves make it difficult for them to survive, but have been found in water as deep as 60 meters.

Although you can find zebra mussels on the bottom and hard surfaces of many bodies of water, it is not advised to catch, eat, or keep them as pets. They are edible, but do not taste good. The mollusks do not have enough nutrients to serve as other pets’ food, either. They also filter feed in waters with lots of pollutants, absorbing those toxins into their bodies. This means they contain a high concentration of toxins not safe for people or animals to consume.

Instead of hunting for or catching zebra mussels, the governments of most nations advise doing what they can to fight their invasion. They recommend cleaning, draining, and drying your boat or other watercraft, and using high-pressure, hot water (at least 120°F) when possible, after taking it out of the water. You should also never take water in a bucket, boat well, or tank from one body of water to another. Always empty water onto land to avoid accidentally transporting larvae.

Predators and Prey

Zebra mussels live best in plankton-rich water with high levels of calcium. They need calcium to make their shells. Calcium level also relates to the presence of hard surfaces on which they can attach. Although the mussel can slowly crawl to a new location, it prefers to find one spot and attach itself there for as long as possible.

Drawing their nutrition from the water, they do not need to move unless it is necessary for survival. One of the key facts of their survival is that being stationary plays a big role in how their predators find them and also how they obtain their nutrients.

What eats a zebra mussel?

Scientists are still researching the food chain related to zebra mussels. But some of the animals that eat them include crabs, drumfish, river redhorse suckerfish, river carpsuckers, and smallmouth buffalo fish. Diving ducks and other waterfowl sometimes eat them, too.

Other species may occasionally feed on them. But the mussels do not taste good and contain too few nutrients to support a healthy fish diet. Humans should not eat zebra mussels because of their bad taste and the pollutants they absorb.

What does a zebra mussel eat?

Adult zebra mussels feed on plankton, waste, and debris. They filter it from the water in which they live, processing up to a liter each day. In essence, they filter the water through their bodies, keeping the nutrients they need and disposing of the material they do not. In polluted water, the toxins are also absorbed into their bodies.

Reproduction and Lifespan

Zebra mussels live for 2 to 5 years on average. By 2 years of age, they can reproduce. To do this, the female releases eggs into the water where the male releases sperm. One female can release up to 1 million eggs per year. A male can release up to 200 million sperm. After fertilization, an average of 500,000 eggs per meter hatch and release larvae called veligers.

The surviving veligers travel on water currents and swim freely. Their developing calcium shells weigh enough, at about 2 to 3 weeks of age, to enable them to settle on a hard underwater surface. About 10,000 young settlers each day are firmly attached to their chosen spot to continue growing into adults. During this time and for the rest of their lives, they filter water and draw nutrients into their bodies.

The attachment involves the use of thread-like strands extending from their bodies, called byssal threads. These threads use a sticky substance, similar to glue, to keep them in place. Although they are firmly locked down, only about 95% of the young survive into adulthood.

Fishing And Cooking

Humans do not generally eat zebra mussels. They are nutrient-poor and contain a high concentration of pollutants from the water they filter through their bodies. They also do not taste good.