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How Can I Recognize the Asian Shore Crab?

Asian shore crabs are native to the western Pacific ocean. Since the late 1980s, Asian shore crabs have spread to the Atlantic coast of North America from Maine to North Carolina. Authorities in the United States consider this crab an invasive species, because it may interfere with the food supplies of native species of fish and other shellfish. These crabs also reproduce rapidly; female Asian shore crabs can lay up to 50,000 eggs three to four times in each breeding season. Check the crab's color, size and shape to identify an Asian shore crab.

Instructions

- 1
  Examine the crab's environment. Asian shore crabs prefer to inhabit rocky areas and crevices. They often hide underneath debris or in mussel beds and oyster reefs.
- 2
  Estimate the size of the crab. Asian shore crabs are small. The carapace, or upper shell, ranges from 35 to 42 mm wide -- about 1 1/2 inches to 2 inches.
- 3
  Check the shape of the carapace; the bodies of these crabs are square. You should notice three spiny growths on each side of the carapace.
- 4
  Examine the crab's color. Asian shore crabs range in color from red to orange-brown. They can also have shades of green and purple. The claws sport red spots, while the legs will have both light and dark bands.
- 5
  Check the base of the claws. Male Asian shore crabs have a bulb-like knob in this area. Female Asian shore crabs do not have this knob, but they do tend to have a wider abdomen than the males.

Animals & Science