The California mussel (''Mytilus californianus'') is a large edible

mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and Freshwater bivalve, freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other ...

, a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusk in the family Mytilidae. This species is native to the west coast of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

, occurring from northern Mexico to the Aleutian Islands of Alaska. California mussels are found clustered together, often in very large aggregations, on rocks in the upper

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

on the open coast, where they are exposed to the strong action of the surf.

Shell description

The shell of this species is thick and is often in length, sometimes larger still. The shell is blue on the outside with a heavy brown

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods and ...

which is usually worn off except near the growing edge of the shell. The beaks of the shell are often eroded. The shell has coarse radial ribbing and irregular growth lines on the outer surface. The inner surface of the shell is blue and faintly pearly. Like other mytilids, the animal is attached to the substrate with a very strong and elastic byssus. The shell is primarily made of carbonates. In the 1950s that was mostly aragonite with some

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

, but by 2017/2018 the proportions had reversed. This was surprising given that previously ''some'' increase in aragonite was observed in ''warmer'' waters, and the ocean temperature has risen since then, making researchers expect an increase in aragonite. However it was the opposite - showing that the deciding factor in ''M. californianus'' shell carbonate composition is ocean acidification - because calcite withstands acidity better.

Ecology

The California mussel prefers the high

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

, low sediment conditions found on open rocky coasts. However, they do not colonize bare rock easily, instead preferring the shelter of pre-existing mussels and their biological filaments. Mussels attach themselves to the hard surfaces using their thread-like byssus. Given the right circumstances, California mussels can grow up to 200 mm (8 inches) in length and may live for more than 20 years. However, mortality in intertidal open coastal environments is often high, resulting from battering from driftwood and other debris, wave pounding, predation,

desiccation Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

, and disease. Predators of California mussels include the ''

Pisaster ''Pisaster'' (from Greek ', "pea", and ', "star"Cleveland P. Hickman et al., ''Integrated Principles of Zoology'' (St. Louis: Times Mirror / Mosby College Pub., 1984),p. 469) is a genus of Pacific sea stars that includes three species, ''P. b ...

starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...

. They feed on plankton.

Human use

California mussels were an important food source for the Native Americans who lived on the Pacific Coast prior to European contact. On California's Northern Channel Islands, archaeological evidence shows that they were harvested continuously for almost 12,000 years.

Erlandson Erlandson is a Swedish patronymic surname, meaning "son of Erland", and may refer to: * Axel Erlandson (1884–1964), Swedish American horticulturist * Erland Erlandson (c. 1790–1875), Dano-Canadian trader and explorer * Eric Erlandson (born 19 ...

et al. (2008) documented a decline in the average size of harvested California mussels on San Miguel Island during the past 10,000 years, a pattern they attributed to growing human populations and increased predation pressure from human fishing. Hogan (2008) notes more specific archaeological recovery from the Chumash in the period 800 to 1300 AD. California mussels continue to be harvested as sources of both food and bait up and down the Pacific Coast of North America. The flesh of the California mussel tends to be orange in color. They can be baked, boiled, or fried like other

s, clams, and oysters. While these mussels are usually edible, care needs to be taken, because during times of red tide in any given locality, California mussels may contain harmful levels of the toxins which can cause paralytic shellfish poisoning.

In science

The

keystone species A keystone species is a species which has a disproportionately large effect on its natural environment relative to its abundance, a concept introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in maintaini ...

concept was coined, in 1969, by the zoologist Robert T. Paine, professor emeritus of the University of Washington, to explain the relationship between ''

Pisaster ochraceus ''Pisaster ochraceus'', generally known as the purple sea star, ochre sea star, or ochre starfish, is a common seastar found among the waters of the Pacific Ocean. Identified as a keystone species, ''P. ochraceus'' is considered an important indi ...

'', a species of

, and ''Mytilus californianus''.

References

Notes

Sources

* Erlandson, Jon M., T. C. Rick, T. J. Braje, A. Steinberg, & R.L.Vellanoweth. 2008. ''Human Impacts on Ancient Shellfish: A 10,000 Year Record from San Miguel Island, California.'' Journal of Archaeological Science 35:2144-2152.
C. Michael Hogan, ''Los Osos Back Bay'', Megalithic Portal, ed. Andy Burnham (2008)
* Schmidt, D.
A Review of California Mussel ("Mytilus californianus") Fisheries Biology and Fisheries Programs
Canadian Stock Assessment Secretariat Research Document 99/187 (PDF) * McLean, James. 1969. ''Marine Shells of Southern California'', Los Angeles County Museum of Natural History {{Taxonbar, from=Q3016358 Mytilus (bivalve) Marine molluscs of North America Molluscs of the Pacific Ocean Molluscs of the United States Molluscs of Canada Molluscs of Mexico Fauna of California Fauna of the Northwestern United States Western North American coastal fauna Natural history of the Channel Islands of California ~ Seafood in Native American cuisine Bivalves described in 1837 Taxa named by Timothy Abbott Conrad