Mytilus galloprovincialis is one of the three principal, closely related species in the Mytilus edulis complex of blue mussels, which collectively are widely distributed on the temperate to subarctic coasts of both the Northern and Southern Hemispheres, and often are dominant inhabitants on hard substrates of the intertidal and nearshore habitats. M. galloprovincialis will often hybridize with its sister taxa, the closely related Mytilus edulis and Mytilus trossulus, when they are found in the same locality. M. galloprovincialis is considered the most warm-water-tolerant species of the three, and has the most southerly distribution in Europe and North America.
Distribution
In Europe, Mytilus galloprovincialis is found in the Mediterranean Sea and the Black Sea, and on the Atlantic coasts, in Portugal, north to France and the British Isles and Norway. Recently this species has also been found in the European Arctic including northern Norway and Svalbard In the northern Pacific the species is found along the coast of California, where it was introduced from Europe by human activity in the early 20th century, and also in the Puget Sound region of Washington state, where it has been subject to aquaculture. It is also present as an invasive species on the Asian coast throughout Japan, including Ryukyu Islands, as well as in North Korea and around Vladivostok in Russia. Mytilus galloprovincialis is also present as a native lineage in parts of the Southern Hemisphere. In addition there are populations introduced from the north recently with human activity. These lineages are distinguished by genetic characters. No original Mytilus populations lived in southern Africa, but the Mediterranean mussel was introduced from Europe in 1984 and is now the dominant low intertidal mussel on the West Coast. The distribution spans an area from the Namibian border to Port Alfred, intertidally to just below the low tide border. M. galloprovincialis is also found in New Zealand, Australia and South America.
Description
This animal grows up to 140 mm in length. It is a smooth-shelled mussel with a slightly broader base than that of the black mussel, with which it is often confused in South Africa. Its shell is blue-violet or black, but may shade to light brown.
