The blue mussel (Mytilus edulis), also known as the common mussel, is a medium-sized edible marine bivalve mollusk in the family Mytilidae, the mussels. Blue mussels are subject to commercial use and intensive aquaculture. Systematically blue mussels consist of a group of (at least) three closely related taxa of mussels, known as the Mytilus edulis complex. Collectively they occupy both coasts of the North Atlantic (including the Mediterranean) and of the North Pacific in temperate to polar waters, as well as coasts of similar nature in the Southern Hemisphere. Mytilus edulis is commonly harvested for food throughout the world, from both wild and farmed sources. Undated, no illustrator credited.