U.S. Fish and Wildlife Service
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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

Spectaclecase - Cumberlandia monodonta

Cumberlandia monodonta
(Say, 1829)

Subfamily Unioninae

Threeridge - Amblema plicata

Amblema plicata
(Say, 1817)

Purple wartyback - Cyclonaias tuberculata

Purple wartyback
Cyclonaias tuberculata
(Rafinesque, 1820)

Elephantear - Elliptio crassidens

Elliptio crassiden
(Lamarck, 1819)

Spike - Elliptio dilatata

Elliptio dilatata
(Rafinesque, 1820)

Ebonyshell - Fusconaia ebena

Fusconaia ebena
(Lea, 1831)

Wabash pigtoe - Fusconaia flava

Wabash pigtoe
Fusconaia flava
(Rafinesque, 1820)

Washboard - Megalonaias nervosa

Megalonaias nervosa
(Rafinesque, 1820)

Sheepnose - Plethobasus cyphyus

Plethobasus cyphyus
(Rafinesque, 1820)

Round pigtoe - Pleurobema sintoxia

Round pigtoe
Pleurobema sintoxia
(Rafinesque, 1820)

Monkeyface - Quadrula metanevra

Quadrula metanevra

(Rafinesque, 1820)

Wartyback - Quadrula nodulata

Quadrula nodulata
(Rafinesque, 1820)

Pimpleback - Quadrula pustulosa

Quadrula pustulosa
(Lea, 1831)

Mapleleaf  - Quadrula quadrula

Quadrula quadrula
(Rafinesque, 1820)

Pistolgrip - Tritogonia verrucosa

Tritogonia verrucosa
(Rafinesque, 1820)

Subfamily Anodontinae

Elktoe - Alasmidonta marginata

Alasmidonta marginata
(Say, 1818)

Flat floater - Anodonta suborbiculata

Flat floater
Anodonta suborbiculata
(Say, 1831)

Rock pocketbook - Arcidens confragosus

Rock pocketbook
Arcidens confragosus
(Say, 1829)

White heelsplitter - Lasmigona c. complanata

White heelsplitter
Lasmigona complanata
(Barnes, 1823)

Creek heelsplitter - Lasmigona compressa

Creek heelsplitter
Lasmigona compressa
(Lea, 1829)

Flutedshell - Lasmigona costata

Lasmigona costata
(Rafinesque, 1820)

Giant floater - Pyganodon (=Anodonta) grandis

Giant floater
Pyganodon (=Anodonta) grandis
(Say, 1829)

Salamander mussel - Simpsonaias ambigua

Salamander mussel
Simpsonaias ambigua
(Say, 1825)

Creeper - Strophitus undulatus

Strophitus undulatus
(Say, 1817)

Paper pondshell - Utterbackia (=Anodonta) imbecillis

Paper pondshell
Utterbackia (=Anodonta) imbecillis
(Say, 1829)

Subfamily Lampsilinae

Mucket - Actinonaias ligamentina

Actinonaias ligamentina
(Lamarck, 1819)

Butterfly  - Ellipsaria lineolata

Ellipsaria lineolata
(Rafinesque, 1820)

Plain pocketbook - Lampsilis cardium

Plain pocketbook
Lampsilis cardium
(Rafinesque, 1820)

Higgins' eye - Lampsilis higginsii

Higgins' eye
Lampsilis higginsii
(Lea, 1857)

Fatmucket - Lampsilis siliquoidea

Lampsilis siliquoidea
(Barnes, 1823)

Yellow sandshell - Lampsilis teres anondontoides

Yellow sandshell
Lampsilis teres anodontoides
(Rafinesque, 1820)

Slough sandshell - Lampsilis teres teres (Source: Dr. David H. Sansbery)

Slough Sandshell
Lampsilis teres teres
(Rafinesque, 1820)

Fragile papershell - Leptodea fragilis

Fragile papershell
Leptodea fragilis
(Rafinesque, 1820)

Black sandshell - Ligumia recta

Black sandshell
Ligumia recta
(Lamarck, 1819)

Pondmussel - Ligumia subrostrata

Ligumia subrostrata
(Say, 1831)

Threehorn wartyback - Obliquaria reflexa

Threehorn wartyback
Obliquaria reflexa
(Rafinesque, 1820)

Hickorynut - Obovaria olivaria

Obovaria olivaria
(Rafinesque, 1820)

Pink heelsplitter - Potamilus alatus

Pink heelsplitter
Potamilus alatus
(Say, 1817)

Fat pocketbook - Potamilus capax

Fat pocketbook
Potamilus capax
(Green, 1832)

Pink papershell - Potamilus ohiensis

Pink papershell
Potamilus ohiensis
(Rafinesque, 1820)

Bleufer - Potamilus purpuratus

Potamilus purpuratus
(Lamarck, 1819)

Lilliput - Toxolasma parvus

Toxolasma parvus
(Barnes, 1823)

Fawnsfoot - Truncilla donaciformis

Truncilla donaciformis
(Lea, 1828)

Deertoe - Truncilla truncata

Truncilla truncata
(Rafinesque, 1820)

Freshwater Mussel Species by Navigation Pool or Tributary
Navigation Pools
Navigation Pools
Click for larger scale
Major Tributaries
Upper Mississippi River System
Click for larger scale
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Mussel anatomy

Since 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
mussel anatomy (.gif)
Click for larger scale
mussel anatomy - side (.gif)

Species Identification and LocationThreatened and Endangered MusselsLife HistoryEcology Mussel Harvest on the RiverCurrent ThreatsMussel Conservation ActivitiesOngoing Studies and ProjectsMultimediaTeacher ResourcesFrequently Asked QuestionsGlossaryReferencesLinks to Other Mussel Sites


Department of the InteriorU.S. Fish & Wildlife ServiceU.S. Geological Survey
Last updated on December 28, 2006