Sentinel Crab

Macrophthalmus latifrons

Systematics: Brachyura Family Ocypodidae

Distinguishing Characters:
The yellowish-brown carapace is up to 20 mm wide, 1.5 times as long as wide with two teeth on each side behind the corner of the carapace. The eyestalks are long, lying either protected along the front of the carapace or held erect. The chelipeds of the male are stronger than those of the female.

Habitat and Distribution:
The sentinel crab builds a deep burrow among weeds on mudflats in sheltered bays like Western Port. It ranges only from Victoria to South Australia.

General Biology:
Sentinel crabs live in burrows which they excavate in soft mud, and feed on rotting seagrass. Although they can commonly be seen walking and exploring when the tide is out they quickly retreat to their burrows when danger appears. Wading birds prey on sentinel crabs. All members of the Ocypodidae have long eyestalks. The semaphore crabs, whose males have one huge coloured claw, are spectacular tropical representatives.