Hemigrapsus sanguineus
Hemigrapsus sanguineus, also known as the Asian shore crab, has a square shaped carapace, unlike the usual triangular crab shape. This carapace exhibits a mottled color ranging from purple to brownish orange to green. Perhaps the most characteristic morphology trait of the Asian shore crab is the banding pattern on their legs. Alternating between light and dark bands, the legs of H. sanguineus make it easy to distinguish from other New England crabs. Adults can attain widths of 3 cm to 4 cm, but no observations were made above 2 cm at the study site.
H. sanguineus feeds on many organisms in the intertidal, including macroalgae, grass, juvenile fish, amphipods, gastropods, bivalves, barnacles, and polychaetes.
Hemigrapsus sanguineus is indigenous to the Western Pacific coast from Russia to Hong Kong, China and around Japan. In 1988, the crab was reported in Cape May, New Jersey, probably as a result from ballast water (http://cars.er.usgs.gov). H. sanguineus larvae are suspended in water for up to a month before developing, allowing them to live in ballast tanks for long trips. By 1996, the crab had established healthy populations across southern New England. Now, specimens can be found from Maine to as far south as North Carolina (O’Connor, 2001). Unlike Carcinus maenas populations which have more or less stabilized since its introduction, H. sanguineus has been spreading its range since it was first recorded on the Atlantic North American coast and may very well still be in the process of expansion.
All H. sanguineus photos from http://cars.er.usgs.gov/pics/nonindig_crustaceans/nonindig_crustaceans.html