European green crabs are faster, more dextrous and aggressive hunters than native crabs giving them the advantage and outcompeting other species. This species native range is the Atlantic coast of Europe and northern Africa, from Norway and the British Isles south to Mauritania. Their non-native Range: South Africa, Australia, Japan, and both coasts of North America. These are easy to identify if you are able to get a good look at the carapace and count the spines. Typically, invasive crab species have fewer than 5 (sometimes 6) spines, whereas native species in the US have more than 6.
Photo from: Coastal SOS app