• Mississippi National River and Recreation Area


    National River & Recreation Area Minnesota

Purple Wartyback

(Cyclonaias tuberculata) Rafinesque, 1820
A Purple Wartyback mussel
K.S. Cummings, Illinois Natural History Survey
Other Common Names:
Purple Pimpleback; Wartyback; Missouri mapleleaf; Deerhorn.
Medium to large rivers in gravel or mixed sand and gravel.
Up to 5 inches (12.7 cm).
Outer Shell Color:
The outside shell color is brown or black.
Inner Shell Color:
Usually deep purple, or occasionally white with a purple tint.
Shell Thickness:
Moderately thick and heavy.
Shell Outline:
The entire shell outline is shaped like a circle, except for a flattened extension of the shell directly off of one side of the point where the two shell halves join. This extension has a straight edge, shaping this one "corner" of the shell somewhat like a square.
Shell Surface:
Rough: many small pimple-like bumps scattered over three-quarters of the outer shell surface. The surface without bumps is always located along the outer surface following the shell edge that is opposite from the squared-off "corner" of the shell. The bumps may form into small ridges along the squared-off outer surface of the shell. Entire shell surface may look either flattened or somewhat bulged-out. Looking at the inner shell, there is a deep depression: it forms a visible bulge on the outer shell surface (called the beak). This beak is covered in wavy lines, which look as though a fine-toothed comb were dragged in a wavy motion over the beak's outer surface.
Scientific Description:
Brown or black, heavy shell. Subrectangular, totally tuberculate. Beak sculpture extends onto disc. Incurrent papillae aborescent. Excurrent aperture entire (fused), lacking papillae.
Similar Looking Mussels:
Host Fish:
Black Bullhead, Yellow Bullhead, Channel Catfish, Flathead Catfish
Widespread but uncommon in most of the Midwest.
Minnesota State Listing:
Federal Listing:

Did You Know?

Lock and Dam Number 1 from a long distance.

At Lake Itasca, the elevation of the Mississippi River is 1,475 feet above sea level. It drops to sea level at the Gulf of Mexico. More than half of that drop occurs within the state of Minnesota.