Geukensia demissa, a species of bivalve mussel, is a native to the Atlantic coast of North America. The common names include ribbed mussel, Atlantic ribbed marsh mussel and ribbed horse mussel. Its ribbed shell usually grows to attain a 10 centimeter length.
Ribbed mussel can be found in coastal waters from the Gulf of St. Lawrence in eastern Canada south along the western Atlantic coast to Florida. In the Gulf of Mexico, is it replaced by the southern ribbed mussel Geukensia granosissima.
This mussel has been introduced to Texas, California, Mexico, and Venezuela.
These mussels reside in the intertidal zone attached to hard surfaces or embedded in sediment with the help of their byssal threads. They are frequently seen in saltwater and estuarine marshes.
Image Caption: Waquoit Bay National Estuarine Research Reserve. Ribbed mussel – Geukensia demissa. Massachusetts, Waquoit Bay. Credit: Joan Muller/Wikipedia (CC BY 2.0)