Carcinus maenas is a common littoral crab, and an important invasive species. Carl Linnaeus (Latinized as Carolus Linnaeus, also known after his ennoblement as, May 23 new style (13 May old style 1707 who laid the foundations for The book Systema Naturae was one of the major works of the Swedish doctor of medicine Carolus Linnaeus. Littoral refers to the coast of an ocean or sea or to the banks of a river lake or estuary Crabs are decapod Crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (βραχύ / brachy Introduced species|Weed Invasive species is a phrase with several definitions It is listed among the 100 "world's worst invasive alien species" . 
C. maenas is known by different names around the world. In the British Isles, it is generally referred to simply as the shore crab. The British Isles (Irish variously Na hOileáin Bhriotanacha, Oileáin Iarthair Eorpa, Éire agus an Bhreatain Mhór; Ellanyn Goaldagh Eileanan In North America and South Africa, it bears the name green crab or European green crab. The Republic of South Africa (also known by other official names) is a country located at the southern tip of the continent of Africa In Australia and New Zealand, it is referred to as either the European green crab or European shore crab. For a topic outline on this subject see List of basic Australia topics. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island
C. The Eemian interglacial era, now known as the Eemian Stage is temporally equivalent to the Sangamon Stage in North America, the Ipswichian Stage in The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands maenas has a carapace up to 60 mm long and 90 mm wide , with five short teeth along the rim behind each eye, and three undulations between the eyes. A carapace is a dorsal section of an Exoskeleton or shell in a number of animal groups The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to The undulations, which protrude beyond the eyes are the simplest means of distinguishing C. maenas from the closely-related C. aestuarii, which can also be an invasive species. Carcinus aestuarii is a Littoral Crab, native to the Mediterranean Sea. In C. aestuarii, the carapace lacks any bumps and extends forward beyond the eyes. Another character for distinguishing the two species is the form of the first and second pleopods (collectively the gonopods), which are straight and parallel in C. The decapod Crustacean such as a crab lobster shrimp or prawn is made up of nineteen Body segments grouped into two main body parts the Cephalothorax The decapod Crustacean such as a crab lobster shrimp or prawn is made up of nineteen Body segments grouped into two main body parts the Cephalothorax aestuarii, but curve outwards in C. maenas . 
The colour of C. maenas varies greatly, from green to brown, grey or red. This variation has a genetic component but is largely due to local environmental factors .  In particular, individuals which delay moulting become red–coloured rather than green. Ecdysis is the Molting of the Cuticula in Arthropods and related groups ( Ecdysozoa) Red individuals are stronger and more aggressive, but are less tolerant of environmental stresses, such as low salinity or hypoxia . In Psychology and other social and Behavioral sciences aggression refers to behavior that is intended to cause harm Salinity is the Saltiness or dissolved salt content of a body of Water. For other uses of the term "hypoxia" see Hypoxia. Hypoxia or oxygen depletion is a phenomenon that occurs in aquatic environments 
C. maenas is native to European and North France coasts as far as the Baltic Sea in the east, and Iceland and central Norway in the north, and is one of the most common crabs throughout much of its range. The Baltic Sea is a Brackish inland sea located in Northern Europe, from 53°N to 66°N Latitude and from 20°E to 26°E Longitude. Iceland, officially the Republic of Iceland ( ( Ísland or Lýðveldið Ísland ( Norway ( Norwegian: Norge ( Bokmål) or Noreg ( Nynorsk) officially the Kingdom of Norway, is a Constitutional In the Mediterranean Sea, it is replaced by the closely-related species Carcinus aestuarii.
C. maenas was first observed on the east coast of North America in Massachusetts in 1817, and may now be found from Nova Scotia to Virginia. The Commonwealth of Massachusetts ( is a state located in the New England region of the northeastern United States. Nova Scotia (ˌnəʊvəˈskəʊʃə ( Latin for New Scotland; Alba Nuadh Nouvelle-Écosse is a Canadian province located on Canada 's The Commonwealth of Virginia ( is an American state
In Australia, C. For a topic outline on this subject see List of basic Australia topics. maenas was first reported in the late 18th century, in Port Phillip Bay, Victoria. "Port Phillip" may also refer to a Local Government Area called the City of Port Phillip. It has since spread along the coast of Victoria, reaching New South Wales in 1971, South Australia in 1976 and Tasmania in 1993. South Australia is a state of Australia in the southern central part of the country Tasmania is an Australian island and state of the same name It is located south of the eastern side of the Continent, being separated from it by Bass One specimen was found in Western Australia in 1965, but C. Western Australia is a state occupying the entire western third of the Australian continent. maenas has not been seen in the area since . 
C. maenas first reached South Africa in 1983, in the Table Docks area near Cape Town . The Republic of South Africa (also known by other official names) is a country located at the southern tip of the continent of Africa Cape Town (Kaapstad Xhosa: Ikapa) is the second most populous city in South Africa, forming part of the metropolitan municipality of the  Since then, it has spread at least as far as Saldanha Bay in the north and Camps Bay in the south, over 100 km apart. Saldanha Bay is a Natural harbour on the south-western coast of South Africa, north west of Cape Town. Camps Bay is an affluent Suburb of Cape Town, South Africa. In the European winter it
In 1989, C. maenas was found in San Francisco Bay, California, on the Pacific coast of the United States. San Francisco Bay is a shallow productive Estuary through which water draining from approximately forty percent of California, flowing in the Sacramento California ( is a US state on the West Coast of the United States, along the Pacific Ocean. The Pacific Ocean is the largest of the Earth 's Oceanic divisions The United States of America —commonly referred to as the Until 1993, it was not able to extend its range, but reached Oregon in 1997, the state of Washington in 1998 and British Columbia in 1999 . Oregon ( is a state in the Pacific Northwest region of the United States. Washington ( is a state in the Pacific Northwest region of the United States. British Columbia (ˌbrɪtɨʃ kəˈlʌmbiə ( BC) ( (la Colombie-Britannique C 
Other appearances that have not, however, led to invasions have been recorded in Brazil, Panama, Hawaii, Madagascar, the Red Sea, Pakistan, Sri Lanka and Myanmar; Japan has been invaded by a related crab, either C. aestuarii or a hybrid of C. |utc_offset = -2 to -4 |time_zone_DST = BRST |utc_offset_DST = -2 to -5 |cctld Panama, officially the Republic of Panama (República de Panamá) is the southernmost country of Central America. The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the Madagascar, or Republic of Madagascar (older name Malagasy Republic) is an Island nation in the Indian Ocean off the southeastern The Red Sea is a Salt water Inlet of the Indian Ocean between Africa and Asia. Pakistan () officially the Islamic Republic of Pakistan, is a country located in South Asia, Southwest Asia, Middle East and Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka ( Sinhalese:, இலங்கை known as Ceylon before 1972 is an Island Burma, officially the Union of Myanmar ( pjìdàunzṵ mjàmmà nàinŋàndɔ̀ is the largest country by geographical area in mainland Southeast Asia. For a topic outline on this subject see List of basic Japan topics. Carcinus aestuarii is a Littoral Crab, native to the Mediterranean Sea. In Biology, hybrid has two meanings The first meaning is the result of interbreeding between two animals or plants of different taxa. aestuarii and C. maenas . 
It is believed, based on the ecological conditions, that C. maenas could eventually extend its range to colonise the Pacific coast of North America from Baja California to Alaska . Baja California (pronounced ˈbɑːhɑː kælɨˈfɔrnjə in English is the northernmost state of Mexico. Alaska ( Аляска Alyaska) is a state in the United States of America, in the northwest of the North American continent  Similar ecological conditions are to be found on many of the world's coasts, with the only large potential area not to have been invaded yet being New Zealand; the New Zealand government has taken action, including the release of a Marine Pest Guide  in an effort to prevent colonisation by C. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island maenas.
C. maenas can live in all types of protected and semi-protected marine and estuarine habitats, including habitats with mud, sand, or rock substrates, submerged aquatic vegetation, and emergent marsh, although soft bottoms are preferred. Marine is an Umbrella term. As an adjective it is usually applicable to things relating to the Sea or Ocean, such as Marine biology, Marine An estuary is a semi-enclosed Coastal body of Water with one or more Rivers or Streams flowing into it and with a free connection to the open In Geography, a marsh, or morass, is a type of Wetland which is subject C. maenas is euryhaline, meaning that it can tolerate a wide range of salinities (from 4 to 52 ‰)and survive in temperatures from 0 °C to 30°C . Euryhaline organisms are able to adapt to a wide range of salinities Salinity is the Saltiness or dissolved salt content of a body of Water. A per mil or per mille (also spelled permil, per mill or promille) ( Latin, literally meaning 'for (every thousand' is a tenth Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The Celsius Temperature scale was previously known as the centigrade scale.  The wide salinity range allows C. maenas to survive in the lower salinities found in estuaries. An estuary is a semi-enclosed Coastal body of Water with one or more Rivers or Streams flowing into it and with a free connection to the open
A molecular biological study using the COI gene found genetic differentiation between the North Sea and the Bay of Biscay, and even more strongly between the populations in Iceland and the Faroe Islands and those elsewhere. Molecular biology is the study of Biology at a molecular level The Enzyme cytochrome c oxidase or Complex IV () is a large Transmembrane protein complex found in Bacteria and the Mitochondrion History See also History of genetics The existence of genes was first suggested by Gregor Mendel (1822-1884 who in the 1860s studied inheritance Cantabrian Sea redirects here Not to be confused with Biscay Bay Newfoundland and Labrador or Biscayne Bay. Iceland, officially the Republic of Iceland ( ( Ísland or Lýðveldið Ísland ( The Faroe Islands or Faeroe Islands or simply Faroe(s or Faeroes (Føroyar meaning " Sheep Islands" Færøerne Old Norse This suggests that C. maenas is unable to cross deeper water . 
Females can produce up to 185,000 eggs and larvae develop offshore in several stages before their final moult to juvenile crabs in the intertidal zone . A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example  Young crabs live in meadows of kelp, for instance Posidonia oceanica, until they reach adulthood. Posidonia oceanica is a species of Seagrass that is endemic to the Mediterranean Sea. 
C. maenas is a predator and feeds on many organisms, particularly bivalve molluscs (such as clams, oysters, and mussels), polychaetes and small crustaceans . Bivalves are Molluscs belonging to the class Bivalvia. They have two-part shells and typically both valves are symmetrical along the hinge line Clam is a word which can be used for all some or only a few Species of Bivalve Mollusks the word is a Common name which has The common name oyster is used for a number of different groups of Bivalve Mollusks most of which live in marine habitats or Brackish water. The common name mussel is used for members of several different families of Clams or Bivalve Molluscs, from both saltwater and freshwater habitats The Polychaeta or polychaetes are a class of Annelid worms generally marine Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting  They are primarily nocturnal, although activity also depends on the tide, and crabs can be active at any time of day . 
C. maenas has the ability to disperse by a variety of mechanisms  including: ballast water, ships' hulls, packing materials (seaweeds) used to ship live marine organisms, bivalves moved for aquaculture, rafting, migration of crab larvae on ocean currents, and the movement of submerged aquatic vegetation for coastal zone management initiatives. Ballast is used in Sailboats to provide moment to resist the lateral forces on the Sail. Seaweed is a loose colloquial term encompassing macroscopic Multicellular, benthic marine Algae. Aquaculture is the farming of freshwater and saltwater organisms including Molluscs Crustaceans and aquatic plants A raft is any flat floating structure for travel over water It is the most basic of Boat design characterized by the absence of a hull. A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example An ocean current is continuous directed movement of Ocean water. Thresher et al.  found that in Australia C. maenas dispersed mainly by rare long-distance events, possibly caused by human actions.
In California, preferential predation of C. California ( is a US state on the West Coast of the United States, along the Pacific Ocean. maenas on native clams (Nutricola spp. ) resulted in the decline of the native clams and an increase of a previously introduced clam (the amethyst gem clam, Gemma gemma) . The amethyst gem clam, Gemma gemma, is a small Species of marine Bivalve Mollusk.  C. maenas has been implicated in the destruction of the soft-shell clam (Mya arenaria) fisheries on the east coast of the United States and Canada and the reduction of populations of other commercially important bivalves (such as scallops, Argopecten irradians, and northern quahogs, Mercenaria mercenaria) . A scallop (ˈskɒləp or /ˈskæləp/ is a marine Bivalve Mollusk of the family Pectinidae. The hard clam ( Mercenaria mercenaria) or quahog, is an edible Marine Bivalve Mollusc which is native to the  The prey of C. maenas includes the young of bivalves  and fish, although the effect of its predation on winter flounder, Pseudopleuronectes americanus is minimal . The winter flounder, Pseudopleuronectes americanus, (also known as black back) is a Flatfish of the family Pleuronectidae.  C. maenas can, however, have substantial negative impacts on local commercial and recreational fisheries by preying on the young of species such as oysters and the Dungeness crab, or competing with them for resources . For the fishing industry and the practice of fishing see Fishing. The common name oyster is used for a number of different groups of Bivalve Mollusks most of which live in marine habitats or Brackish water. The Dungeness crab is a species of Crab that inhabits Eelgrass beds and water bottoms from the Aleutian Islands in Alaska to Santa 
Due to its potentially harmful effects on ecosystems, various efforts have been made to control introduced populations of C. maenas around the world. In Edgartown, Massachusetts, a bounty was levied in 1995 for catching C. Edgartown is a town located on Martha's Vineyard in Dukes County, Massachusetts, United States. maenas, in order to protect local shellfish, and 10 tons were caught . Shellfish is a Culinary and Fisheries term for those aquatic Invertebrate animals that are used as Food: various species of molluscs 
There is evidence that the native blue crab in eastern North America, Callinectes sapidus, is able to control populations of C. The blue crab ( Callinectes sapidus, from the Greek calli ="beautiful" nectes ="swimmer" and Latin maenas; numbers of the two species are negatively correlated, and C. In Probability theory and Statistics, correlation, (often measured as a correlation coefficient) indicates the strength and direction of a linear maenas is not found in Chesapeake Bay, where Callinectes sapidus is most frequent . The Chesapeake Bay is the largest Estuary in the United States.  On the west coast of North America, C. maenas appears to be limited to upper estuarine habitats in part by predation by native rock crabs (Cancer antennarius and Cancer productus) and competition for shelter with a native shore crab, Hemigrapsus oregonensis .  Host specificity testing has recently been conducted on Sacculina carcini, a parasitic barnacle, as a potential biological control agent of C. Sacculina is a Genus of Barnacles that parasitize Crabs The adults bear no resemblance to the barnacles that cover ships and piers Parasitism is a type of symbiotic relationship between Organisms of different Species. A barnacle is a type of Arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence distantly related to maenas .  In the laboratory, Sacculina settled on, infected, and killed native California crabs, including the Dungeness crab, Cancer magister, and the shore crabs Hemigrapsus nudus, Hemigrapsus oregonensis and Pachygrapsus crassipes. The Dungeness crab is a species of Crab that inhabits Eelgrass beds and water bottoms from the Aleutian Islands in Alaska to Santa Dungeness crabs were the most vulnerable of the tested native species to settlement and infection by the parasite. Although Sacculina did not mature in any of the native crabs, developing reproductive sacs were observed inside a few Cancer magister and Hemigrapsus oregonensis. Any potential benefits of using Sacculina to control C. maenas on the west coast of North America would need to be weighed against these potential non-target impacts . 
C. maenas has also caused significant problems in the Republic of Ireland where predation of bottom-cultured mussels has been recorded in several counties (Kerry, Wexford, Waterford), and a number of control programmes have been instigated by mussel producers. Ireland ( Irish: Éire, ˈeːrʲə is a country in north-western Europe. The common name mussel is used for members of several different families of Clams or Bivalve Molluscs, from both saltwater and freshwater habitats County Kerry ( Contae Chiarraí in Irish) is a southwestern county of Ireland. County Wexford (Contae Loch Garman is a maritime county in the southeast of Ireland, in the province of Leinster. County Waterford (Contae Phort Láirge is a County in the province of Munster on the south coast of Ireland. "Hard-eye" shrimp creels are typically used to fish C. maenas in Ireland; the creels are baited, deployed and fished in 24-hour cycles, being typically deployed in strings along the boundaries of mussel beds in order to lure the crabs out of the mussel beds. Some producers pay levies for the removal of crabs, but in most cases, C. maenas catches are sold for processing into food products. This is, however, a small market and the relatively low value of C. maenas (€500 per tonne) and high transport costs (refrigerated lorry €170 per tonne) means that fishing C. Please update other articles as well to avoid contradiction within Wikipedia e This article is about the tonne or metric ton For other tons see Ton. maenas is uneconomical unless it forms part of a control programme to protect more valuable shellfish beds .
C. maenas is fished on a small scale in the north-east Atlantic Ocean, with approximately 1200 tonnes being caught annually, mostly in France and the United Kingdom. For the fishing industry and the practice of fishing see Fishing. This article is about the tonne or metric ton For other tons see Ton. This article is about the country For a topic outline on this subject see List of basic France topics. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located In the north-west Atlantic, C. maenas was the subject of fishery in the 1960s, and again since 1996, with up to 86 tonnes being caught annually .