''Perna perna'', the brown mussel, is an economically important

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

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Mytilidae The Mytilidae are a family (biology), family of small to large Marine life, marine and Brackish water, brackish-water bivalve molluscs in the order (biology), order Mytilida. One of the genera, ''Limnoperna fortunei, Limnoperna'', even inhabits f ...

. It is harvested as a food source but is also known to harbor toxins and cause damage to marine structures. It is native to the waters of

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

, and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

and was introduced in the waters of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

Description

''Perna perna'' is usually 90 mm long although it can reach sizes of up to 120 mm. The mussel is easily recognized by its brown color but its identifying characteristic is the "divided posterior retractor mussel scar". Its pitted resillal ridge also differentiates the mussel from other bivalves. Similar species include the European mussel, '' Mytilus galloprovincialis'', and the black mussel, '' Choromytilus meridionalis''. The European mussel is similar in shape and color to the brown mussel and shares its native habitat on the south-western coast of Africa. The European mussel is also more resistant to human disturbance such as use for baits and consumption. It is out-competing the brown mussel as it is more resistant to certain

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

s. The black mussel has similar shape and size although it lacks the distinguishable pitted resillal ridge. The brown mussel can also be mistaken for the more famous greenish-brown species ''

Perna viridis ''Perna viridis'', known as the Asian green mussel, is an economically important species of mussel, a bivalve belonging to the family (biology), family Mytilidae, or the "true mussels". It is harvested for food but is also known to harbor toxins ...

'', as their color and shell shape can change depending on environmental conditions.

Right and left valve of the same specimen: File:Perna perna 03.jpg, Right valve File:Perna perna 04.jpg, Left valve

''Perna perna'' var. ''picta''
Right and left valve of the same specimen: File:Perna perna 05.jpg, Right valve File:Perna perna 06.jpg, Left valve

''Perna perna'' var. ''elongata''
Right and left valve of the same specimen: File:Perna perna 01.jpg, Right valve File:Perna perna 02.jpg, Left valve

Habitat and distribution

The brown mussel is native to the

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

and

sub-tropical The subtropical zones or subtropics are geographical and climate zones immediately to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 3 ...

regions of the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

and Western Indian Ocean . It is found in waters off the west coast of Africa and the coast of South America up to the

Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...

, as well in the East Coast of Africa and Madagascar. It is accidentally introduced as an

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

to the coast of

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

via the

boat hulls A hull is the watertight body of a ship, boat, submarine, or flying boat. The hull may open at the top (such as a dinghy), or it may be fully or partially covered with a deck. Atop the deck may be a deckhouse and other superstructures, such as a ...

and water ballasts of ships from

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

. Its distribution include:

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. The brown mussel naturally colonizes rocky shores but can also attach to submerged man-made objects such as navigation buoys, petroleum platforms and shipwrecks. The adult brown mussel can tolerate a temperature range of 10 to 30 °C and a

salinity Salinity () is the saltiness or amount of salt (chemistry), 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 dimensio ...

range of about 15 to 50 ppt. Its colonization of the hard strata improves that surface's marine ecology. The colonization increases surface area, encouraging other marine organisms such as

limpet Limpets are a group of aquatic snails with a conical gastropod shell, shell shape (patelliform) and a strong, muscular foot. This general category of conical shell is known as "patelliform" (dish-shaped). Existing within the class Gastropoda, ...

polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...

barnacle Barnacles are arthropods of the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea. They are related to crabs and lobsters, with similar Nauplius (larva), nauplius larvae. Barnacles are exclusively marine invertebra ...

snail A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial molluscs, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gas ...

s and

alga Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, suc ...

e to settle there as well.

Ecology and life history

The mussel utilizes

external fertilization External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. It is contrasted with internal fertilization, in which sperm are introduced via insemination and then ...

during the spawning season between May and October although this is also reported to occur in December. The two sexes release eggs and sperm to the water during spawning to produce

veliger A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod taxono ...

larvae. Fifteen hours after fertilization the larvae have well-developed hinge teeth. Ten to twelve days after fertilization the larvae undergo

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

where byssal threads are secreted. The larvae then settle on rocky surfaces. The brown mussel is a

filter feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

and feeds on

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

and suspended organic materials. It is plagued by the parasite ''Proctoeces maculatus'' and an unidentified bucephalid sporocyst which castrates both sexes. On the African coastline it is preyed upon by the whelk '' Nucella cingulata'',

lobster Lobsters are Malacostraca, malacostracans Decapoda, decapod crustaceans of the family (biology), family Nephropidae or its Synonym (taxonomy), synonym Homaridae. They have long bodies with muscular tails and live in crevices or burrows on th ...

octopus An octopus (: octopuses or octopodes) is a soft-bodied, eight-limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like oth ...

es, gulls and the African black oystercatcher. On the South American coastline, it provides food for '' Callinectes danae'', '' Cymatium parthenopeum'', ''

Chicoreus brevifrons ''Chicoreus brevifrons'', common name the West Indian murex, is a species of predatory sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails.Houart, R. (2011). Chicoreus brevifrons (Lamarck, 1822). Accessed through: Wo ...

'', '' Thais haemastoma'', and '' Menippe nodifrons''.

Importance to humans

''Perna perna'' is harvested as a food source in Africa and South America. The bivalve is considered for cultivation as it can grow quickly to the commercial size of 60 to 80 mm in just 6 or 7 months. It is also well-suited to tropical and subtropical regions. However, the mussel can harbor

saxitoxin Saxitoxin (STX) is a potent neurotoxin and the best-known paralytic shellfish toxin. Ingestion of saxitoxin by humans, usually by consumption of shellfish contaminated by toxic algal blooms, is responsible for the illness known as paralytic she ...

from consumed

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

s. Its consumption has caused outbreaks of

paralytic shellfish poisoning Paralytic shellfish poisoning (PSP) is one of the four recognized syndromes of shellfish poisoning, which share some common features and are primarily associated with bivalve mollusks (such as mussels, clams, oysters and scallops). These shellfi ...

. The brown mussel is known to aggregate in such large amounts that it is able to sink

navigational buoys Navigation is a field of study that focuses on the process of monitoring and controlling the motion, movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navig ...

. It also coexists with the Asian green mussel in fouling water pipes and marine equipment. It is less resistant to chlorination than ''

'' and thus easier to control. However, it is recommended that the concentration of chlorine used for chlorination be above the tolerance level of ''Perna viridis'', the tougher of the two biofouling mussels.

References

* Dautzenberg, Ph. (1929). ''Contribution à l'étude de la faune de Madagascar: Mollusca marina testacea. Faune des colonies françaises, III (fasc. 4)''. Société d'Editions géographiques, maritimes et coloniales: Paris. 321-636, plates IV-VII pp. * MacNae, W. & M. Kalk (eds) (1958). ''A natural history of Inhaca Island, Mozambique''. Witwatersrand Univ. Press, Johannesburg. I-iv, 163 pp.
''The sea shells of Dar es Salaam: Part 2: Pelecypoda (Bivalves)''. Tanganyika Notes and Records 63
* Richmond, M. (Ed.) (1997). ''A guide to the seashores of Eastern Africa and the Western Indian Ocean islands.'' Sida/Department for Research Cooperation, SAREC: Stockholm, Sweden. . 448 pp. * Steyn, D.G. & Lussi, M. (1998) ''Marine Shells of South Africa. An Illustrated Collector’s Guide to Beached Shells''. Ekogilde Publishers, Hartebeespoort, South Africa, ii + 264 pp. page(s): 202 * Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). ''European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification.'' Collection Patrimoines Naturels, 50: pp. 180–213 * Gofas, S.; Afonso, J.P.; Brandào, M. (Ed.). (S.a.). ''Conchas e Moluscos de Angola = Coquillages et Mollusques d'Angola. hells and molluscs of Angola'' Universidade Agostinho / Elf Aquitaine Angola: Angola. 140 pp.
Branch, G.M. et al. (2002). ''Two Oceans''. 5th impression. David Philip, Cate Town & Johannesburg
* Ardovini, R.; Cossignani, T. (2004). West African seashells (including Azores, Madeira and Canary Is.) = Conchiglie dell'Africa Occidentale (includes Azzorre, Madeira e Canarie). English-Italian edition. L'Informatore Piceno: Ancona, Italy. . 319 pp. * Streftaris, N.; Zenetos, A.; Papathanassiou, E. (2005). ''Globalisation in marine ecosystems: the story of non-indigenous marine species across European seas.'' Oceanogr. Mar. Biol. Annu. Rev. 43: 419-453 * Turgeon, D. D., W. G. Lyons, P. Mikkelsen, G. Rosenberg, and F. Moretzsohn. 2009. ''Bivalvia (Mollusca) of the Gulf of Mexico, Pp. 711–744'' in Felder, D.L. and D.K. Camp (eds.), Gulf of Mexico–Origins, Waters, and Biota. Biodiversity. Texas A&M Press, * Huber M. (2010) ''Compendium of bivalves. A full-color guide to 3,300 of the world’s marine bivalves. A status on Bivalvia after 250 years of research''. Hackenheim: ConchBooks. 901 pp., 1 CD-ROM

External links

{{Taxonbar, from=Q3017896 Mytilidae Molluscs of the Atlantic Ocean Marine molluscs of Africa Marine molluscs of Europe Molluscs of South America Molluscs of Chile Commercial molluscs Molluscs described in 1758 Taxa named by Carl Linnaeus