• First recorded in the United States at Townsend Inlet, Cape May County, New Jersey in 1988
• May have been introduced via discharge of ship ballast water transported from the western North Pacific Ocean

• Commonly orange-brown, also green and maroon
• Light and dark bands on legs with red spots on the claws
• Square-shaped carapace (shell) with 3 spines on each side
• Can grow up to 2-3 in (5-7.6 cm) wide

• Prefers rocks and cobble, but may be found in soft sediments and other habitats
• Primarily in mid to low intertidal zones; sometimes below the low-tide line
• Tolerant of a wide range of salinity and temperature
• Tends to aggregate in large numbers under rocks

• Maine to North Carolina
• Native to Russia, Korea, China, and Japan

• Eats young clams, mussels, oysters, larval and juvenile fish, algae, salt marsh grass, and many other species
• May threaten aquaculture