The Asian Shore Crab – Hemigrapsus
sanguineus - was first identified on American shores in New Jersey in 1988.
It's since made its way as far north as
Schoodic Point, Maine, and as far
south as North Carolina. It is expected to continue moving northward along
the Maine coast. The crab is indigenous to waters from southern
Russia to Hong Kong The Japanese
shore crab is invading Long Island Sound and crowding out native species,
according to marine biologists.
Japanese
shore crabs grow to about the size of a silver dollar. The crab’s
identifiable features are a small hard bubble at the crux of its claws;
three spines along each side of its shell (carapace), as opposed the
similar-looking green crab which has five; and a light-and-dark banding
pattern on its legs.
The
crabs inhabit the rocky intertidal zone — between the high tide line and
about one or two feet below low
tide. They are omnivorous, eating macroalgae, salt marsh grass, and
small invertebrates such as amphipods, gastropods, bivalves, barnacles and
polychaetes. To the south, the
crabs’ diet consists of mussels, clams, periwinkles and the European Green
Crab (the latter two are also non-native species). The Asian crab is able to
reproduce several times a year. Whether the crab will have similar dietary
preferences or be able to reproduce as frequently in Maine’s colder
climate remains to be seen.
If
you see the Asian Shore Crab, we would be interested in knowing about it.
Please respond to Peter Thayer at
with the date, location, and number of crabs you have seen. Or Please use this
Questionnaire
Form Page.
Below
are some photographs that might assist to distinguish the Asian Shore Crab
from our native species such as the Rock Crab and the more abundant European
Green Crab.
Green Crab with unusual coloring
