"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. The distribution of the component taxa has been recently modified as a result of human activity (invasive species). The taxa can hybridize with each other, if present at the same locality.
- Mytilus edulis sensu stricto: Native to the North Atlantic. Mytilus edulis platensis ( = Mytilus chilensis), the Chilean mussel: Temperate waters in the Southern Hemisphere.
- Mytilus galloprovincialis, the Mediterranean mussel: Native in the Mediterranean, the Black Sea and Western Europe. Introduced in the temperate North Pacific, South Africa and elsewhere in the Southern Hemisphere. A distinct lineage native to the Southern Hemisphere also exists.
- Mytilus trossulus: North Pacific, northern parts of the North Atlantic, Baltic Sea."