On your next visit to the beach, be on the lookout for evidence of ghost crabs (Ocypode quadrata). If you arrive early in the morning before beach-goers arrive, look closely at the sand to see the crisscross tracks left by the crabs from their late night excursions out onto the beach to scour for food. While they are out, even though they can’t swim, they will periodically enter the shallows of the water to wet their gills before running up the beach to find something else to eat. You’ll also notice holes of varying sizes along the beach—these are the entrances to burrows in which the crabs reside throughout most of the day. After a night away from their burrows, the crabs spend the early hours of the new day making repairs to these burrows. Mainly, this involves removing heaps of sand that managed to slide into the hole during the night. By afternoon, the crabs scuttle into the burrow tunnel where they plug the entrance hole. The ghost crabs retreat into the cool, moist depths of the sand until dusk. Generally, they do not need to leave the burrow during the day to moisten their gills because the hairs on the base of their legs are able to extract water from the damp sand within their burrows to wet their gills. (Text: Student Conservation Association [SCA] Intern Laura Elder) (Photos: IAN/Alexandra Fries and Carol Denson Emory)
Posted on: Mon, 21 Jul 2014 10:10:00 +0000
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