"Look out, monkeyface!"
"Careful, wartyback!"
These may seem like insults, but these exclamations would excite people interested in clean water and healthy fish populations, because monkeyface and wartyback, along with pistolgrip, heelsplitter, and pocketbook, are freshwater mussels. These colorful names belie the unobtrusive appearance of these animals burrowed in the substrate beneath you as you swim, fish, or boat.

fishFreshwater mussels have a remarkable life cycle that is inextricably linked with native fish and healthy waters. The early stage of a mussel's life is spent attached to a host fish, typically a native species. Some species of mussel release their larvae (glochidia) freely into the water. Others package them into structures that resemble small fish (as shown in this photo) or invertebrates. Fish bite on this expecting a meal, but receive a faceful of glochidia instead.

Host fish are amply repaid as adult mussels improve water quality. Mussels filter water as they feed, and mussel beds are often associated with cleaner, clearer water. Freshwater mussels also stabilize stream beds and their shells provide habitat for caddisflies, stoneflies, and other insects that fish eat.

People have used freshwater mussels for millennia. Many Native American tribes gathered mussels for food and used their shells as tools and ornaments. The scale of exploitation changed in the mid-19th century when pearls were discovered, and then mussel shells were used to make buttons. By the mid-20th century, when plastic buttons were introduced, tens of millions of freshwater mussels had been stripped from rivers and creeks. Even today, some mussels are harvested so pieces of shell can be used as 'seeds' in the oyster pearl industry.

musselsNorth America has a remarkable richness of freshwater mussels, with about 300 species. Most of these are found in the east; the west has only eight species. Freshwater mussels are the most imperiled group of animals in North America. Creeks and rivers are threatened by dams, channel modification, pollution from farming and development, water withdrawal, and the spread of alien species, and many of these impacts are further exacerbated by climate change. Seventy-one eastern species are protected under the U.S. Endangered Species Act, and many more are declining.

Until recently, very little was known about freshwater mussels in the western states. There may be only a handful of species but they are no less important for healthy creeks. To help fill this gap in knowledge, Xerces recently completed a status review of western species. In collaboration with mussel researchers and museums, we collected thousands of mussel records and compared each species' historical and current distribution. Western species in dramatic decline include: Xerces is also working with watershed organizations in the Northwest, training staff and volunteers to survey for native and invasive mussel species in urban and urbanizing streams. With this information, the conservation needs of freshwater mussels can be better considered in stream management decisions.

Visit these links to learn more about freshwater mussels in your region and what you can do to protect them:

One mussel can filter up to 18 gallons of water a day!


Some mussels can live up to a century!  


Of the 1,000 species of mussels worldwide, around 300 are native to North America!   



mussel guide cover Freshwater Mussels of the Pacific Northwest 

Download for free or purchase a hard copy from our online store.
1971 - 2011: Forty Years of Conservation
The Xerces Society is a nonprofit organization that protects wildlife through the conservation of invertebrates and their habitat. The Society has been at the forefront of invertebrate protection worldwide for forty years, harnessing the knowledge of scientists and the enthusiasm of citizens to implement conservation programs.

To learn more about our work, please visit
Your contribution goes directly to support
• innovative conservation programs
• effective education and advocacy
• scientific and popular publications
If you are not already a member, please consider joining the Xerces Society. As a member, you will receive two issues of our member magazine Wings each year. For more information on membership or to renew your membership please visit the membership page on our website. Please email if you have any questions regarding membership.
Please visit our online store for books and publications on invertebrate conservation, including popular titles such as:
Eliza and the Dragonfly
Macroinvertebrates of the Pacific Northwest
Banner Image:
Western pearlshell freshwater mussel (Margaritifera falcata) by Marie Fernandez, USFWS.

In-text Images:
Broken rays mussel (Lampsilis reeveiana) (top) and empty shells left by a racoon (bottom) by M. C. Barnhart, Unio Gallery.
The Xerces Society 4828 SE Hawthorne Blvd. Portland, Oregon 97215 USA tel 855.232.6639

Copyright 2011 The Xerces Society. All rights reserved.