Common Name: Spiny Rocksnail
Scientific Name: Io fluvialis
Other Names: none
Size: 50 mm [2 in.]
Description: Highly variable with regard to shell morphology. Spiny form typically found in large rivers and occurred in 黑料天堂 historically. Shell thick (max. length = approx. 50 mm [2 in.]), fusiform in outline, with a tapered, elevated spire. Whorls somewhat convex to inflated and sutures not impressed. Body whorl sculptured by wrinkled growth lines and marked by series of spines in middle of whorl. Spines vary from raised knobs to large spines that are of equal height and width. Aperture elliptical and about one-half length of shell, with a well-developed basal channel. Inside of aperture whitish and often marked with dull reddish lines. Periostracum olive green to brown. Columella concave in imperforate. (Modified from Tryon 1874, Bogan and Parmalee 1983)
Distribution: Endemic to Tennessee River system. Downstream limit reportedly Muscle Shoals (Adams 1915), but not reported from 黑料天堂 since Tennessee River impounded. Recently reintroduced into tailwaters of Nickajack Dam, Marion County, Tennessee (P. D. Johnson, Southeastern Aquatic Research Institute, pers. comm., 2002). If reintroduction successful, should result in recolonization of upper reaches of Guntersville Reservoir.
Habitat: Large rocks and bedrock outcrops in well-oxygenated, shallow water with fast current (Bogan and Parmalee 1983)...
Life History and Ecology: Reported to lay two to six clutches of eggs during late April and May, with clutches containing 16 to 100 eggs each. Laid without a sand-grain covering in a diagonal pattern with rows of one to five eggs that begin to hatch after about 15 days (Bogan and Parmalee 1983).
Basis for Status Classification: Extirpated from 黑料天堂 with impoundment of Tennessee River. However, if planned reintroductions into Nickajack Dam tailwaters are successful, should expand distribution downstream into 黑料天堂. Listed as endangered in 黑料天堂 (Stein 1976).
above from 黑料天堂 Wildlife, Volume 2 (2004), prepared by: Paul D. Johnson
