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Rocky Mountain Ridged Mussel

Gonidea angulata



Endangered (Federal)
Red List (Provincial)


The Rocky Mountain Ridged Mussel is a large freshwater mussel. Its shell is trapezoidal and up to 12.5 cm long. The surface of the shell is marked by well-defined growth rings with a prominent ridge at the beak. The colour of the shell ranges from greenish in juveniles to bluish-black in adults. The inside of the shell is white tinged with coppery blue.

Highly invasive and destructive Zebra and Quagga Mussels are substantially smaller - about 3 cm long

This mussel can be found in fresh water in various sizes of lakes and streams. It prefers shallow water where the flow is constant and where the bottom is composed of fine material. This species avoids murky, nutrient loaded water and can commonly be found partly or completely buried.

Within Canada, the Rocky Mountain Ridged Mussel is only found in the Okanagan Valley.


-Destruction and degradation of lakeshore and riparian habitat
-Changes in the aquatic environment due to pollution
-Changes in water temperature due to climate change
-Excessive nutrient-loading of lakes and streams from fertilizer runoff
-Invasive species (such as zebra mussels)

You Can Help!

-Reduce the use of fertilizers near water bodies as much as possible
-Dispose of chemicals and other pollutants properly and never pour them down the drain
-Avoid disturbing riparian and lakeshore areas where these mussels are known to live
-Prevent bank erosion by planting native trees and shrubs along river and lake shores
-Report all sightings of this species and invasive mussels

Public domain photo courtesy of the Akimi King/US Fish and Wildlife Service


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