The European green crab (Carcinus maenas) is a small marine crustacean native to European and North African coasts, extending as far as the Baltic Sea in the east, and Iceland and Central Norway in the north. It is one of the most common crabs throughout much of its range. European green crabs are one of the most widespread invasive marine species, having reached Washington in 1996. When their populations grow too large, they compete with other shellfish, disturb the sediment, and destroy eelgrass, which is an important habitat for Dungeness crab and salmon. They have also invaded North America and threaten coastal ecosystems and fisheries.