THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION

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

Like the western pearlshell, the ridged mussel has a thick shell, and can live for many decades, filtering organic matter from the water. It inhabits cold, clean creeks and rivers, and is not likely to be found in a wetland.

The ridged mussel is very distinctive because, as its name suggests, it has a prominent ridge that runs from the umbo, or hinge, to the opposite corner of the shell. The ridge is usually even prominent in worn shell fragments.

The Western Ridged Mussel is widely distributed west of the continental Divide from California to British Columbia. Unfortunately, this species has dissapeared from much of its original range. Much research is needed to further understanding of this species' ecology, such as its fish hosts and reproductive biology.

Size: xlarge
Identifying feature(s): The shell is thick and has a distinct ridge from the umbo to the farthest edge: this is a distinctive feature that can even be used in worn shells and fragments; inside of shell pearly white.
Habitat: cold and clean creeks and rivers
Tolerance: sensitive