While visiting New York last week, I flipped a few rocks along the East Coast and encountered quite a few of these small crustaceans; they were often found in dense aggregations.
Adults are small, measuring about an inch and a half in shell width. They have a squarish shell and light and dark bands on their legs.
Though native to the western Pacific Ocean from Russia to Hong Japan, it is likely that Asian Shore Crabs were discharged at harbors in the United States as larvae from the ballast water of a cargo ship.
This creature is not a picky eater, and feeds on a wide range of plants and animals. It can tolerate a wide range of environmental conditions. These characteristics help to make it successful in areas where it is not native.
Although undeniably cute, Asian Shore Crabs have displaced both large and small native crabs along the East Coast.