Living On The Edge

Introduction

Species in Recovery

Success Stories

Endangered Animals

Endangered Plants

Counties were Species
Can be viewed

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.

Photographer:Mike Davis

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.