Atlantic Ghost Crab, Ocypode quadrata

Atlantic Ghost Crab, Ocypode quadrata. Crab found strolling down a beach at sunrise in Longboat Key, Florida, January 2017. Size: 5.0 cm (2.0 inches) x 4.5 cm (1.8 inches). Photograph courtesy of Carol Snow, Del Mar, California.

General Information: The Atlantic Ghost Crab, Ocypode quandrata, is a member of the Ocypodidae family of ghost and fiddler crabs. They are one of twenty known species of global ghost crabs. The name ghost crab comes from their pale coloration and being a nocturnal species. The Atlantic Ghost  being described in historic literature as an “occult, secretive alien from the ancient depths of the sea” and also has been named The Fleet-footed One of White. The Atlantic Ghost Crabs date to the Pleistocene Period, approximately two million years ago. At present their populations are being heavily impacted by human development that include sediment compression, food supply reduction and light pollution. They are now less common on beaches that are frequented by humans.

Identification: Adult Atlantic Ghost Crabs have a gray shell with yellowish tan legs, With the ability to change their color, juveniles colored to match their background. They have rectangular shells that reach a maximum width of 5.0 cm (2.0 inches) with stalked eyes that are on a swivel that affords 360-degree vision. They are capable of generating sound, which is a type of “growl” they make by grinding the teeth in their stomach together. During mating season the males compete in a heavily ritualized manner that does not include physical contact.

Habitat and Range: The Atlantic Ghost Crab resides in 1.2-meter (4-foot) long burrows within the sand during daylight hours while during cold periods can be found well above the tidal line and can be up to a quarter mile from the sea. Typically juveniles are found closer to the ocean than adults. They are a semi-terrestrial species spending the majority of their time as terrestrial animals. However, they require access to the ocean for survival, requiring water for their gills, and homes for the larva released as apart of the reproduction cycle. They have the ability to close these burrows with sand during periods with excessive heat. The females release their eggs at the oceans edge and the larvae develop in the ocean. The Atlantic Ghost Crabs are common along the Atlantic coast of North America and the only ghost crab found along the Atlantic seaboard. The are found on all Mexican beaches of the Atlantic Ocean. They are difficult to catch by hand as they are quite speedy and have strong pinchers that can inflict instant pain. The report than they can dig faster than an hombre with a shovel has not been proven conclusively.

Diet: The Atlantic Ghost Crabs are nocturnal omnivores that feed on clams, other crabs, detritus, insects, loggerhead turtle eggs and plant materials, However they are capable of surviving long periods without food. The Atlantic Ghost Crabs have very few terrestrial predators or competitors, especially at night.

Conservation Status:  From a conservation perspective the Atlantic Ghost Crab has not been formally evaluated. However, they are common and of limited interest to most and should be considered to be of Least Concern.

Synonyms:  Cancer quadratus, Monolepis inermis, Ocypode arenaria, Ocypode rhombea, Ocypode albicans, Ocypode arenarius, and Sesarma quadrata.