The European green crab (Carcinus
maenas) is a small shore crab (adults measure about 3" across) whose
native distribution is along the coasts of the North and Baltic Seas.
Although known by the common name of green crab, the shell (carapace)
color can vary from dark, mottled green to orange or red, with yellow
patches on the dorsal carapace. The crab is an able and effective forager—capable
of learning and improving upon its food-gathering skills. Studies have
shown that the green crab is quicker and more dexterous than most crabs,
and can open bivalve shells in more ways than other crabs. One adult crab
reportedly can eat 40 half-inch, clams each day and can devour crabs as
large as itself. Green crabs also prey on numerous other organisms--making
these crabs potential competitors for the food sources of native fish and
bird species.
The green crab has already
invaded numerous coastal communities outside of its native range,
including South Africa, Australia, and both coasts of North America. An
able colonizer and efficient predator, this small shore crab has the
potential to significantly alter any ecosystem it invades. It has been
blamed for the collapse of the soft-shell clam industry in Maine.
Text: http://www.wsg.washington.edu
