Freshwater
Mussels of the Upper Mississippi River System
Species Identification and Location
Freshwater mussels (Family: Unionidae) are bivalved (two-shelled) mollusks that live in the sediments of rivers, streams, and lakes. These soft-bodied animals are enclosed by two hard shells made mostly of calcium and connected by a hinge. In the Upper Mississippi River System, they come in a variety of shapes and colors.
Unlike many regions of the country, most mussels of the Midwest can be identified using a combination of written descriptions, photographs, and range maps found in field guides. Compare your specimen to a photograph, make sure that the species you have chosen occurs in your area, then read the full species description to confirm your identification. Since some species of mussels look alike, you may need a basic understanding of mussel anatomy to make correct identifications.
The Upper Mississippi River System includes commercially-navigable portions of the Mississippi River from the Ohio River upstream to Minneapolis-St. Paul in Minnesota; it also includes navigable portions of the Illinois River and other major tributaries. Historically, 51 species of freshwater mussels lived in the Upper Mississippi River System. The following 44 species have been found in mussel surveys conducted in the past 35 years in the Upper Mississippi or Illinois Rivers. Mussel surveys have also been conducted in other tributaries.
Subfamily Cumberlandinae |
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|---|---|
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Spectaclecase |
Subfamily Unioninae |
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|---|---|
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Threeridge |
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Purple wartyback |
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Elephantear |
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Spike |
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Ebonyshell |
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Wabash pigtoe |
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Washboard |
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Sheepnose |
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Round pigtoe |
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Monkeyface |
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Wartyback |
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Pimpleback |
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Mapleleaf |
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Pistolgrip |
Subfamily Anodontinae |
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|---|---|
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Elktoe |
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Flat floater |
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Rock pocketbook |
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White heelsplitter |
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Creek heelsplitter |
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Flutedshell |
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Giant floater |
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Salamander mussel |
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Creeper |
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Paper pondshell |
Subfamily Lampsilinae |
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|---|---|
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Mucket |
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Butterfly |
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Plain pocketbook |
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Higgins' eye |
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Fatmucket |
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Yellow sandshell |
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Slough Sandshell |
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Fragile papershell |
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Black sandshell |
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Pondmussel |
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Threehorn wartyback |
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Hickorynut |
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Pink heelsplitter |
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Fat pocketbook |
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Pink papershell |
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Bleufer |
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Lilliput |
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Fawnsfoot |
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Deertoe |
| Freshwater Mussel Species by Navigation Pool or Tributary | |
|---|---|
Navigation Pools Click for larger scale |
Major
Tributaries Click for larger scale |
| Linked documents are Adobe Acrobat .pdf files. Acrobat Reader required (free). | |
Mussel anatomySince some species of mussels look alike, you may need a basic understanding of mussel anatomy to make correct identifications. These diagrams show a typical mussel shell and its "soft" inner tissues and organs. |
Click for larger
scale |
Click for larger scale |