New York Natural Heritage Program
Black Sandshell
Ligumia recta (Lamarck, 1819)
Bivalves

General Description [-]
This mussel has a thick, subelliptical, elongate shell reaching about 20 cm long. The periostracum is dark green and shiny with rays in younger animals, but in older specimes it is dark brown to black. The hinge teeth are heavy; pseudocardinals triangular or slightly compressed. The nacre is most often white, but can be pinkish or purple. The shells of females are broader and more rounded posteriorly than those of the males (Strayer and Jirka 1997).

Identifying Characteristics [-]
The shells of this species are distinctively large, heavy, and elongate with a black periostracum and strong hinge teeth (Strayer and Jirka 1997).

Best Life Stage for Proper Identification [-]
Adults.

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 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 which readily attack displaying females, causing them to release glochidia onto the gills of the fish (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 include the Banded Killifish, White Crappie, Largemouth Bass, Bluegill, Green Sunfish, Orangespotted Sunfish, and Walleye (Strayer and Jirka 1997). Khym and Layzer (2000) reported that Sauger was the most suitable host species.
Black Sandshell 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 is a long-term breeder; its gravid period overlaps in different individuals and extends nearly year round (Clarke 1981).
J F M A M J J A S O N D
Reproducing
The time of year you would expect to find Black Sandshell reproducing (green shading) in New York.
Similar Species
  • Spike (Elliptio dilatata)
    This species is noticeably smaller than L. recta, but younger black sandshells may be confused. Ligumia recta has a shiny green or black periostracum, while that of E. dilitata is rougher and browner.