Seanet Mid Intertidal

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Mytilus californianusConrad, 1837
Phylum Mollusca, Class Bivalvia, Subcl. Pteriomorpha, Order Mytiloida, Family Mytilidae

California mussel; shell bluish-black, heavy; anterior end pointed, posterior rounded; prominent radial ribs (often eroded). Attached with tough, proteinaceous byssal threads. Filter feeder.

Very abundant, exposed outer coast, forms multilayer beds in upper-mid intertidal zone. Dominant space competitor, preyed on by sea stars (Pisaster ochraceus), sea otters, whelks, crabs & birds.

Geogr. Range: Aleutian Islands, Alaska to Baja
Similar species: bay mussels, Mytilus trosselus & the introduced M. galloprovincialis have thinner smoother shells usually lacking radiating ridges; both occur in more wave-protected locations.
Image: alga is Endocladia muricata