Ghost Crab (Ocypode quadrata)

A large Ghost Crab, seen at sunset at Myrtle Beach, South Carolina. This example is about 2 inches across.

Ghost Crab (Ocypode quadrata)

This small Ghost Crab is well-camouflaged.

Ghost Crab:
Hungry Nocturnal Ghosties

By Patricia B. Mitchell.

Ghost crabs are rather cute crustaceans which are difficult to spot because they are sand-colored and somewhat diaphanuous. Their stalked black eyes give them an extraterrestrial appearance, and they scurry about in a rather purposeful manner — but you will probably only see them at dusk or at night. Ghost Crabs scavenge the beach, looking for tasty things to eat. Once a year, when baby sea turtles are hatching out, they enjoy special feasts. They drag the three-inch-long hatchlings down into their underground burrows, and devour them.

You might notice the golfball-sized entrance holes of the Ghost Crab burrows in the dry sand of the upper beach, or in the sand dunes. The burrows extend down 3-4 feet. To watch some species of Ghost Crabs built (or repair) their homes is particularly fascinating. The “Ghostie” brings up clawfuls of sand and tosses them 6-12 inches away from the burrow opening. Later on, the Ghost Crab tromps down the strewn-about sand, and, using its claws, smooths out the surface. (In contrast, other species bring up the sand in the form of little balls and leave them scattered about the entrance.) Crab tracks also clearly mark the burrow entrance. Yet another entrance style is represented by a dome of sand which covers the burrow hole. Obviously some Ghosties are more inclined than others to camouflage their home.

The burrow may slant down at a 45° angle, and has a “turn-about” chamber at the end. The tunnel home is constructed with wet grains of sand so that it will not collapse. In the winter Ghost Crabs hibernate in their burrows, “holding their breath” for six weeks by storing oxygen in specialized sacs near their gills.

When not hibernating, the Ghost Crab has to wet its gills periodically for purposes of both respiration and reproduction. The creature maintains a little seawater in the bronchial chambers. When this supply of water needs to be replenished, the Ghost Crab approaches the shoreline sideways, standing there until a wave washes in far enough to wet him. Then he scampers back to the upper beach. (On occasion a Ghost Crab can wick up enough water from damp sand to serve this purpose.)

Females with egg masses, however, need to frequently enter the water to keep the eggs wet. Although Ghost Crabs cannot swim, the females may turn upside down in the water to ventilate the egg mass which is carried under her tail. The babies begin life in the water, and then become amphibious temporially.

A third reason to sometimes visit the sea is to escape from predators — birds and raccoons, for example.

Besides eating baby sea turtles, the Ghost Crab likes beach fleas, coquina clams, mole crabs, lizards, and carrion. He feeds at night.

When the moon is full, the almost invisible Ghost Crab scuttles across the sand, facing the moon. His large eyestalks are club-shaped and capable of 360° vision, although he can't see straight overhead. (He can retract his periscope-like eyes into grooves on the front of his shell when he senses the need to protect them.) His vision is so acute that he can spot and grab insects in mid-air.

The Ghost Crab's carapace (shell) is rectangular in shape, with nearly vertical sides. His off-white to tan carapace is 1½-2 inches across. He has six strong, hairy legs which can carry him along at speeds up to 10 miles per hour, making him the fastest of all crustaceans. He can run sideways, forward, and backward. He has strong pincers of unequal size. And don't stick your hand down his burrow — he doesn't mind pinching you very hard. (He crushes his victims before gobbling them up.)

On some of the Caribbean Islands, Ghost Crabs are a human food source.


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