Mytilidae

Family: Mytilidae

Group: Marine Invertebrate, Species

Scientific Name	Common Name	Summary
Modiolus modiolus	Northern Horsemussel	The Northern Horsemussel is quickly distinguished by the hairy brown periostracum (the tough skin covering the shell).
Mytilus californianus	California mussel	This is the common mussel of surf-beaten, exposed rocky areas. This species generally doesn't cover its habitat like Pacific Blue Mussel (Mytilus trossulus) sometimes does, and some specimens can be almost a foot in length. Small shells can be distinguished from M. trossulus by their ribs.
Mytilus trossulus	Pacific Blue Mussel	This species looks a lot like California mussel (Mytilus zonarius), but has a thinner shell, lives in calmer, more sedimentation-prone areas, and generally doesn't exceed finger length. As for distinction between this species and exotic species such as M. edulis and M. galloprovincialis, it is essentially impossible. Look out for Paralytic Shellfish Poisoning (PSP) when consuming this tasty bivalve. Especially in calm areas such as harbors and bays, this mussel tends to have threads running between individuals, and the shells may be quite thin and pale.