National Park Service LogoU.S. Department of the InteriorNational Park ServiceNational Park Service
National Park Service: U.S. Department of the InteriorNational Park Service Arrowhead
 
 
Support the National Park Service
Mississippi National River and Recreation AreaKayaking on the Mississippi River near Hastings, Minnesota.
view map
text size:largestlargernormal
printer friendly
Mississippi National River and Recreation Area
Rock Pocketbook
(Arcidens confragosus) Say, 1829
A Rock-pocketbook mussel
K.S. Cummings, Illinois Natural History Survey
Other Common Names:
Rockshell; Grandmaw; Bastard; Black pocketbook; Queen
Habitat:
Medium to larger rivers in pools and areas of reduced flow in mud and sand.
Length:
Large. Up to 2.8 inches (7.1 cm).
Outer Shell Color:
Brown or black. May be dark green to greenish in young mussels.
Inner Shell Color:
White with some iridescent coloring on one-third of the entire inner shell, on the long end (as measured from the the swollen point above where the two shell halves join).
Shell Thickness:
Thin (for its size) to slightly thick.
Shell Outline:
Varies from squarish to oval-shaped. One end is rounded, the other end is somewhat squared-off or narrows slightly to a rounded tip.
Shell Surface:
Rough. The swelling just above where the two shell halves join (the beak)is covered by two rows of small pimple-like bumps. The bumps fan out and spread down the shell's outer surface, sometimes forming two ridges down the shell's surface, or spreading out and fusing to form a rough surface similar to a washboard. Entire shell surface may look swollen or bulged-out.
Scientific Description:
Brown or black, large shell, juveniles greenish. Shell inflated, moderately heavy. Prominent beaks sculptured with two diverging rows of tubercles extending onto disc. In adults this appears as numerous low, broad ridges. Gills often brown.
Similar Looking Mussels:
Washboard, Threeridge (both are more inflated).
Host Fish:
Rock Bass, Gizzard Shad, Channel Catfish, White Crappie
Distribution:
Uncommon to rare in the Midwest.
Minnesota State Listing:
Endangered.
Federal Listing:
None.
A flooded street in 1952  

Did You Know?
In 1952, the Mississippi River flooded hundreds of acres of farmland and multiple cities. Over 2,000 families were homeless because of the high water.
more...

Disclaimer Accessibility Privacy Policy FOIA Notices USA.gov

Last Updated: May 05, 2008 at 11:38 EST