THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION

Aquatic Invertebrates in Pacific Northwest Freshwater Wetlands
An Identification Guide and Educational Resource

This family includes the species Valvata utahensis, which is listed as endangered under the U.S. Endangered Species Act and lost much of its habitat when the Snake River was dammed.

The shells of these relatively small snails (<8mm) are generally flattened, like the Planorbidae, but usually have a detectable cone. They always have an operculum, unless it has been degraded by preservative or is pulled too far into the shell to be seen. The shells of Valvata often have a very circular opening. They may also have ridges running along with the coils.

Size: small to medium
Identifying feature(s): operculum present; flattened shell with discernable cone, circular aperture
Habitat: lakes and cold, free-flowing rivers
Tolerance: moderate