European shore crab
[Image: Michael Marmach]
Status in New Zealand
Not in New Zealand
Legal Status in New Zealand
Unwanted organism
Description
The European shore crab (also called the 'green crab') is native to the Atlantic Coast of Europe and northern Africa. It has been introduced to North America, Japan, South Africa and Australia. It is a habitat generalist that can tolerate a wide range of salinities and temperature, helping it to survive in a range of habitats from the intertidal zone of estuaries to the open ocean. It is also tolerant of low levels of dissolved oxygen and can persist in polluted water.
European shore crabs can live for up to 6 years. Females reproduce at 1-3 years old and are highly fecund, producing between 185,000 to 200,000 fertilised eggs at a time. The free swimming larvae remain in the plankton for up to 90 days, facilitating dispersal by water currents. It may have been spread intentionally for human consumption or through vessel ballast water or as hull fouling.They are nocturnal, feeding mostly at night.
Why is it a problem?
In some areas where it has been introduced, the European shore crab can reach densities of up to 200 per square metre. It consumes a wide range of species, including other crabs and shellfish. Because of this it can have large impacts on the native flora and fauna in estuarine and marine ecosystems. It has also had economic impacts on some shellfish industries.
Hear about the impacts of the European shore crab invasion on shell fisheries in Maine, USA.
Find links to other videos on the European shore crab in our Video catalogue.
What do they look like?
Key features
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European shore crabs are medium-sized with a body width (carapace) of up to 9 cm. The upper carapace of adult crabs is a mottled dark brown to green, with small yellow patches and the underside varies from green to orange to red. Juveniles are normally a light sandy colour. Five pointed spines are located on either side of the eyes, with three rounded lobes present between the eyes. Although relate to paddle crabs, the European shore crab does not have swimming paddles on its hind legs. Download an identification guide
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 [Image: A.M. Arias] |