Shell Crab, Hypoconcha lowei

Shell Crab, Hypoconcha lowei. Crab collected by the commercial fishermen of the greater Los Cabos area, Baja California Sur, August 2009. Size: 6.0 cm (2.3 inches) x 4.8 cm (1.9 inches). Identification courtesy of Dr. Richard Brusca, Tucson, Arizona.

General information: The Shell Crab, Hypoconcha lowei, is fairly common and a member of the Dromiidae Family which are known as Decorator and Sponge Crabs. In Mexico it is known as congrejo caracol. The Shell Crab is given its name due to the fact that their 4th and 5th walking legs are modified to secure bivalve shells onto their carapace. The Shell Crab is a frequent by-catch of deep water shrimp trawlers.

Identification: The Shell Crabs last pair of legs of these crabs has been modified to allow them to attach themselves either to a living sponge, or in the case of Hypoconcha lowei empty clam shells. The Shell Crab’s shell and legs are covered with fine brown hair. Their claws are covered with numerous large white oval denticles (as pictured above). The Shell Crab range from 2.5 cm (1.0 inch) to 6.25 cm (2.5 inches) in width.

Habitat and Range: Shell Crabs are found amongst rubble and on patch reefs from the low intertidal zone to depths up to 90 m (300 feet). They are found throughout the Sea of Cortez and southward along the coast of the mainland down to Guatemala.

Diet: Shell Crabs consume small invertebrates that the collect off the ocean floor.

Conservation Status:  From a conservation perspective the Shell 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.