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European Green Crab

 

Common Name
European Green Crab/Shore Crab

Scientific Name

Carcinus maenas (Linnaeus, 1758)

 

Description

  • varies in color from green, reddish orange or tan, with a darker mottling color on the carapace (shell).
  • the carapace has been found to be up to 10cm wide with 5 distinct triangular teeth on each side (between the widest part of the shell and the eyes)
  • 3 rounded lobes between the eyes
  • the claws of the green crab are both the same size
  • last pair of walking legs are somewhat flattened.

Habitat C. maenas occupies a variety of habitats including protected rocky and cobble shores, sandflats and tidal marshes. They have been known to tolerate a wide variety of environmental conditions including varying temperatures and salinities. They are found in salinities of 4-52 ppt (parts per thousand) and temperatures down to freezing.

Invasion History
The European green crab, Carcinus maenas, has become one of the most successful marine invaders, with an invasion record spanning for two centuries over four continents (according to the Global Invasive Species Database, the green crab has been named in the top 100 of the "World's Worst" invaders!). It is native to Europe from Norway to western Africa but has now invaded and become established in many parts of the world. Since its arrival in New York and New Jersey in 1817, it has expanded northward into Canada and successful colonization has now occurred in Australia, Tasmania, South Africa, Japan and both coasts of North America .

Regional Sightings
On the east coast of Canada, C. maenas has been confirmed in Nova Scotia, New Brunswick, Prince Edward Island and most recently, Newfoundland (click here for a CBC news article on green crabs invading Newfoundland). In Nova Scotia, it is present along the coast of the Bay of Fundy, including Cape Breton and the southern Gulf of St. Lawrence. On Cape Breton Island, green crabs are present in the Bras d’Or Lakes and as far north as Ingonish, as well as estuaries throughout Cape Breton Regional Municipality.

Potential Impacts
Green crabs are omnivorous, meaning they will eat animal or plant material. They are also predators and scavengers, consuming the widest array of marine animals and plants known for any crab in the world. Thus, one of the biggest concerns is that green crabs will displace native species through competition and predation. Furthermore, green crabs have been found to play an important role in the structure of rocky shore communities because they have the ability to greatly alter surrounding habitats (eg. predation on mussels in lower water flow areas alters the whole community in that area) and in Nova Scotia, concerns are growing about the potential impact on commercially important bivalve aquaculture operations.

Additional websites related to the green crab