A Quick Guide to Marine Bioinvasions

If you see a Japanese shore crab, you can help out by contacting one of the following:
  • the Sea Grant Program in your state
  • the local natural history museum
  • a university field station
  • a local U.S. Fish & Wildlife Office
  • Also known as Hemigrapsus sanguineus, this Japanese import was released from ballast water in New Jersey around 1987 and has since pushed its way north into Massachusetts and south into North Carolina. An omnivore with an appetite for young clams, scallops, oysters, algae, fish larvae, and many other species, these crabs may well pose a threat to New England ecosystems and aquaculture operations.

    The Japanese shore crab measures 2 to 3 inches across and has a square-shaped shell with three spines on each side. Its claws have red spots, and its legs have alternating light and dark bands. Depending on its location, this crab can range from a mottled, deep brown to purple, orange, green, and pink.