Mytilus trossulus

The Bay Mussel

Phylum Mollusca
Class Bivalvia
Subclass Pteriomorphia
Order Mytiloida
Family Mytilidae
Genus Mytilus
Species trossulus

Description: 6 to 10 cm long, 3 to 5 high; shiny blue-black to black or brownish; shell has a long rounded triangular shape.

Habitat: Can be found growing in large clumps attached to rocks, docks, pilings, floats and gravel.

Natural History: It attaches to the substrate with its many fine, tough, byssal threads. It is a filter feeder, and the tangled mass of mussels and byssus forms homes for numerous small creatures. Mytilus edulis is very similar to M. trossulus and was thought to be our native bay mussel. Recently it was determined that M. edulis is almost exclusively found on the Atlantic Coast. Some introduced M. edulis have been reported in Puget Sound.