Halloween Crab, Gecarcinus quadratus

Halloween Crab, Gecarcinus quandratus, Female. Crab collected by the commercial fishermen of the greater Los Cabos area, Baja California Sur, November 2009. Size: 10 cm (3.9 inches). Identification courtesy of Richard Brusca, Tucson, Arizona. Dr. Brusca indicated the that claws are normally equal in size but the pictured crab must have lost a claw and is in the generation process.

General information: The Halloween Crab, Gecarcinus quadratus, is a very colorful decapod and member of the Gecarcinidae or Land Crab Family. In Mexico they are known as Moro de Manchas Blancas. These crabs are nocturnal and are known to dig burrows. They have life spans of ten to fifteen years.

Identification: The Halloween Crab has large purple claws, reddish-orange legs and an almost entirely black shell, a pair of yellow, orange or maroon spots behind the eyes and an additional white spot on the lower central portion of the shell. The shells are very smooth and have a central depression. The eyes are on short stalks, near the center of the anterior margin of the carapace. They are known for their burrows that are dug at night that can extend up to 1.5 m (5.0 feet) in length and are known for being highly territorial. They spend much of their time on land but return to the ocean to breed. They are sexually dimorphic with the male Halloween Crab having a maximum shell width of 6.4 cm (2.5 inches) and and the females 5.7 cm (2.2 inches).

Habitat and Range: The Halloween Crab is found primarily on land within mangroves, sand dunes and rainforests along the Pacific coast of Mexico. They are found along the West coast of the mainland from the extreme northern portion of the Sea of Cortez, south along the coast of the mainland to Guatemala. As adults they may spend part of their life living in the rainforests of south and Central America but travel back to the ocean in order to breed. This collection photographed above represents both a size and range extension (to the southwest coast of the Baja) for this species.

Diet:  The Halloween Crabs are considered to be omnivores that feed on algae, fruits, plant materials, small invertebrates and fish, scavenging off anything they can get their claws on. However their primary herbivorous mainly consuming leaf litter and seedlings.

Conservation Status:  From a conservation perspective the Halloween 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. They are utilized by the pet trade at a nominal level.