Photos by cottonmanifesto. Location: Castle Island beach, South Boston.

Urban species #188: European green crab Carcinus maenas

The most common crab along the New England shore is a creature with the telling name of the European green crab. It's thought that the green crab was introduced in the 1700's, either in ballast water or in seaweed (marine algae can be used as a kind of living packing material for shipping edible mollusks and the like). The green crab is so well established in New England that its full ecological impact is lost to history. It is thought that this predator of bivalves helped cause the collapse of softshell clam industries in Maine and other places, in the mid 20th century, however.

In the 1990's green crabs (which actually range in color from greenish to reddish) were found in San Francisco Bay. Shellfishing industries and ecologists all along the Pacific coast are bracing for the impact of this invader, and scrambling to prevent its spread. Green crabs are also established on the Gulf coast, as well as in Japan, South Africa, Australia, etc. etc.

The green crab has a great tolerance for different salinity levels, and can live in almost every coastal environment, from pristine salt marshes to the city wharves. While it has a reputation as a voracious predator that feeds on native crabs and other animals, it is opportunistic, happily eating even barnacles and periwinkles. As a boy I had great success catching them using blue mussels as bait, though Sugar Babies worked nearly as well.

Interestingly, in New England, the green crab is starting to suffer competition from a new invader. The Asian shore crab Hemigrapsus sanguineus was found in New Jersey in 1988, and has spread up and down the east coast. It is established in Boston, and is currently found as far north as Maine south to the Carolinas.



This tiny individual (dwarfed by my wedding ring) may grow to be about 4 inches wide, and may live up to 3 years.


I perceive an air of menace, as this small green crab stares down the camera.


This Asian shore crab was able to cling to my arm and hang upside-down.