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Creeper (Strophitus undulatus)

Creeper (Strophitus undulatus)Photograph courtesy of E. Nedeau

NH Conservation Status: Not listed


NH State Rank Status: Vulnerable to extirpation or extinction (globally secure)


Distribution: Parts of the lower Connecticut, Merrimack, and coastal watersheds.


Description: A medium sized mussel growing up to 3 inches. Shells are greenish-brown or yellowish-brown and have a rough appearance from prominent growth lines. The foot color is bluish-white.


Commonly Confused Species: Eastern elliptio, brook floater, triangle floater, alewife floater, Eastern floater


Habitat: Small streams and rivers with sand, cobble, or gravel substrates.


Life History: Host fish include largemouth bass, yellow perch, fathead minnow, fallfish, golden shiner, and bluegill. Creepers may also use amphibians as hosts, such as the Northern two-lined salamander.


Conservation Threats: Pollution and other general threats shared by freshwater mussels. Although not currently considered of conservation concern in New Hampshire, creepers are listed as ‘Special Concern’ in Massachusetts and Maine so there may be reason for concern in future years.