New York Natural Heritage Program
Eastern Pondmussel
Ligumia nasuta (Say, 1817)
Bivalves

General Description [-]
The shell of the eastern pondmussel is elongate, subelliptical, with a distinct posterior ridge, medium thick, most often < 75 mm long. The posterior end of the shell is drawn out into a well defined blunt point near the midline of the shell. Its beak sculpture is double-looped, the periostracum dark, green to brown, sometimes with fine rays over the posterior part of the shell. Its hinge teeth are well-developed, sharp and delicate; the nacre is a bluish to creamy white (Strayer and Jirka 1997) .

Identifying Characteristics [-]
The long shell, with its distinctive posterior end, makes this species easy to recognize (Strayer and Jirka 1997).

Best Life Stage for Proper Identification [-]
Adult.

Behavior [-]
Adults of this species are sessile with only limited movement in the substrate. Passive downstream movement may occur when they are displaced from the substrate during floods. More major dispersal occurs while glochidia are encysted on their as yet, unknown host(s). Being ectothermic, activity levels of mussels are presumably reduced greatly during colder months of the year. Gravid females of Ligumia display marginal papillae to attract fish hosts for their parasitic larvae. The moving displays attract fish (bass, sunfish, darters), which readily attack displaying females, causing them to release glochidia onto the gills of the fish. These displays slow in low light and stop in the dark, so highly turbid waters may affect the reproductive biology of this species (Corey et al. 2006).

Diet [-]
Adult mussels are filter feeders. Algae, detritus and bacteria are all important food sources. Mussels in turn are eaten by muskrats, raccoons, fish, and birds. The glochidial (larval) host fish species has not been determined, but several Centrachid (sunfish) species as well as bass seem to be suitable (Strayer and Jirka 1997, Corey et al. 2006).
Eastern Pondmussel Images
click to enlarge
The Best Time to See
Little is known about the activity periods of Unionid mussels but they are presumed to be greatly reduced during cold times of the year. Freshwater mussels are most often easiest to locate during late summer when water levels are lowest. This species breeds from August until the following June (Clarke 1981).
J F M A M J J A S O N D
Active Reproducing
The time of year you would expect to find Eastern Pondmussel active (blue shading) and reproducing (orange shading) in New York.
Similar Species
  • Black Sandshell (Ligumia recta)
    Ligumia recta has a smoother periostracum, heavier hinge teeth, and a more rounded posterior end.
  • Eastern Elliptio (Elliptio complanata)
    Elliptio species usually have shorter shells and much heavier hinge teeth.