Species Information

Green crab (Carcinus maenas) Green crab (Carcinus maenas)
P. Erickson for MIT Sea Grant College Program
Green crab (Carcinus maenas)
P. Erickson for MIT Sea Grant College Program
Green crab
Carcinus maenas

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History

• Believed to have first arrived in eastern North America around 1817, most likely in the dry ballast of cargo ships
• Negative impacts on soft-shell clams and other bivalves have been documented since 1950s


Characteristics

• Green to dark brown, sometimes with yellow, orange, or red, with darker mottling
• Walking legs green, speckled with black
• Carapace (shell) has 5 spines on each side
• Can grow up to 3.9 in (10 cm) wide


Habitat

• Salt marshes, sandy beaches, and rocky shores
• Usually on mud, sand, or pebbles
• Prefers sheltered areas
• Usually near the low-tide line
• Tolerates wide range of salinities (as low as 6 ppt)


Known Distribution in the Northeast

• Newfoundland to Delaware; has become the most common crab in many locations throughout this range
• Native to North Atlantic coast of Europe and the North African coast
 


Impacts

• Has become a dominant predator, feeding on clams, oysters, crabs, and mollusks
• Often blamed for collapse of soft-shell clam industry and reduction of other commercially important bivalves, including scallop and northern quahog