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Triangle floater (Alasmidonta undulata)

Triangle floater Photograph courtesy of E. Nedeau

NH Conservation Status: Not listed


NH State Rank Status: Apparently secure (global – apparently secure)


Distribution: All major watersheds in NH.


Description: A medium sized mussel up to 3 inches with a “chunky” appearance. Shell color is generally a mix of greenish-brown or yellow. The inner shell (nacre) is pinkish or bluish-white. The foot is usually white.


Commonly Confused Species: Dwarf wedgemussel, brook floater, creeper


Habitat: Most commonly in rivers and streams with gravely substrates. Less common in lakes and ponds.


Life History: Uses a range of host fish including the common shiner, white sucker, and large-mouth bass.


Conservation Threats: Triangle floaters can tolerate non-flowing water so it is less sensitive to the effects of dams compared with many other freshwater mussels of the Alasmidonta genus (e.g., brook floaters, dwarf wedgemussels). As a filter feeder, like many other freshwater mussels, they are likely sensitive to pollution and habitat degredation.



Triangle floater

Shell of a triangle floater with ruler – Photo by M. Marchand