Description: This freshwater mussel
has a heavy yellow or brown shell often with faint to quite distinct
green rays. The shell is oval or elliptical in shape with a
difference between males and females. The male shell is nearly oval,
while the female shell has a more irregular shape.
Habitat and Habits: The Higgins eye is thought to be a
species that occurs in low numbers throughout its range. It prefers
large rivers with deep water. This species has been reported from
several types of substrate – sand/gravel, gravel and clay/sand.
Very little is known of the reproduction and early life history for
Higgins eye. Freshwater drum and sauger were thought to be the host
species of fish for the larvae (glochidia). However, more recent
studies indicate that largemouth bass, smallmouth bass, yellow perch
and walleye are suitable host species. Like other species of
freshwater unionid mussels, the Higgins eye has a parasitic larval
stage. Larvae (glochidia) are released by the female and they must
attach and become encapsulated in the gills or fins of host fish
species before they can develop to the juvenile.
Distribution: The Higgins eye is known from the Upper
Mississippi River. Historically, this species also occurred in the
Cedar, Wapsipinicon and Iowa rivers in Iowa, but is no longer found
in these rivers.
Conservation Measures: Protection of known Higgins eye
populations in the Mississippi River from habitat alterations has
been the main conservation effort. Surveys for additional
populations have also been conducted in the larger inland rivers of
Iowa. Reintroduction has been initiated in the Iowa River below Iowa
City.
Funding Provided
by U.S. Environmental Protection Agency and
