Green Crab

Green Crab

Carcinus maenas

Color: From dark to light green with yellowish mottling. Females have an orange green back and a red abdomen.

Size: Up to 2 1/2 inches from head to tail. Carapace is 3 inches wide.

Habitat: Rocky shores and jetties on mud banks, salt marshes, and in tidal pools.

Seasonal Appearance: All year; move to deeper waters in winter.

Sensitivity to Human Action 

 LOW

 

 

 

Distinguishing Features and Behaviors:

     The green crab is one of the most common intertidal crabs found in New England. Green crabs have four pairs of legs which they use to scurry sideways. Their front pinchers are almost equal, but one claw is slightly larger and blunt.

     Green crabs are distinguishable from other intertidal crabs by their color and the shape of their carapaces, although they are often mistaken for the white-fingered mud crab when young. They are shaped like a fan, but their carapace is usually square. Between the eye sockets are three sharp points or teeth, and five points run along the side of the carapace, curved toward the side of each eye socket.

     These crabs are predators and scavengers, feeding mostly on and around mussel beds. Green crabs also prey upon small worms, mollusks, and crustaceans. In turn they are a favorite food for many other intertidal inhabitants, including gulls, herons, and bottom fish such as the tautog.

     Juvenile green crabs are found in and around the rocks and seaweeds of the intertidal zone and are frequently exposed with receding tides. Adult crabs forage in the subtidal shore, following the tide, staying submerged much of the time. During the winter months, adults and large juveniles migrate into deeper waters in the bay, while juveniles remain in the harsh intertidal zone, burrowing under rocks and marsh grasses throughout the year.

     The green crab is a voracious crab and is often called the “angry crab.” It is an aggressive fighter and moves quickly, which helps it escape many confrontations. The green crab can tolerate a wide range of environmental extremes in intertidal zones, including low salinity levels, cold temperatures, and drying out. They can withstand brackish conditions and are able to live in salinities as low as 6 parts per thousand.

Relationship to People:

     Introduced to Narragansett Bay from Europe, green crabs have become one of the most common crabs along New England shores, including Narragansett Bay. Until a few decades ago, they were uncommon in Maine, but now they thrive there in the coastal rocky regions.

     They are major predators on soft-shelled clams and are believed to be destructive to the population. They are also used extensively as bait, particularly in the recreational tautog fishery.