Native to Europe but present on the west coast of Vancouver Island since the late 1990s, green crabs are fairly easily distinguished from our common native crab species. Mature individuals can reach about 90 millimeters across its carapace (the large back shell), meaning a fully grown green crab never gets as large as a mature dungeness or red rock crab, but they are much larger than the common shore crabs found under cobbles and stones at many Vancouver Island beaches. Its common name, the green crab, is somewhat misleading — they can be yellow, green, orange or red depending on the crab’s age. But the most useful distinguishing feature is the ten teeth along the front rim of the carapace, five behind each eye.

As with many other plants and animals, the scientific name of the European green crab, Carcinus maenas, comes from the Greek language. In ancient Greek mythology, Carcinus (pronounced car-SYE-nus) was the crab that came to the rescue of the multi-headed serpent Hydra as she battled Heracles (a.k.a. Hercules). Carcinus bit Heracles in the foot, so Heracles crushed him under his heel. For his efforts, the goddess Hera placed Carcinus in the heavens as the star constellation Cancer. Maenas (pronounced MEAN-us) comes from the Maenads, the wild, raving female worshippers of the god Dionysus (god of mystery, wine and intoxication). Somehow, it seems fitting that the European green crab is named after a tenacious heel-biting crab and a bunch of ecstatic women who tended toward violent orgiastic outbursts.

The green crab has been named one of the Top 100 worst alien invaders in the world. Native to Europe and the North Sea, the green crab has been hitch-hiking around the globe since the early 1800s via ships’ ballast, aquaculture operations, transplanted aquatic vegetation, and ocean currents.

It is now established on the western and eastern coasts of North America, in South Africa, Argentina and Australia. The first sightings on Vancouver Island were on the west coast, in Barkley Sound and Clayoquot Sound in the late 1990s. Since then, the green crab has established populations throughout the west coast of Vancouver Island from Esquimalt to Winter Harbour (north of the Brooks Peninsula).

The green crab is fast, aggressive and voracious (sounds like a Greek Maenid). Dubbed the cockroach of the sea, a single crab can eat 40 small clams in a day — digging 15 centimeters into the beach substrate to get at them. It can also crack oysters up to 60 millimeters, threatening wild and cultured oyster populations.