Invasive Species: Green crab

The European green crab (Carcinus maenas) is also known as the shore crab.

Blue = native range, red = current invasive range, green = at risk

This species is native to the waters off the coast of North Western Europe on down to parts of Northern Africa. It has now become invasive in waters off the coast of Australia, South Africa, Canada, Argentina, and Japan. Many other areas of the world are at risk of invasion. Introduction was through the shipping industry, either through ballast water or fouling organisms.

Many of this species' characteristics makes it an incredibly infective invader. It tolerates a wide range of temperatures, salt levels, and types of habitat. It is an omnivore that will eat just about anything it gets its claws on, including known species from 158 genera at least. It is directly linked to falling numbers of several other species of crab as well as some mollusks. It is even linked to the collapse of the soft-shell crab industry in Nova Scotia and New England. $22 million in damages can be linked to this species in the United States alone. Overall, it has caused decreases in biomass and biodiversity of estuaries where it is found.

This species is currently on the list of 100 World's Worst Invasives at #18.

Images are from Wikimedia Commons under Creative Commons licenses: one, two.