Baja Elbow Crab, Mesorhoea belli

Baja Elbow Crab, Mesorhoea belli. Provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, February 2011. Size: 4.0 cm (1.6 inches) x 2.9 cm (1.1 inches). Identification courtesy of Don Cadien, Marine Biology Laboratory, Carson, California.

General information: The Baja Elbow Crab, Mesorhoea belli, is an uncommon member of the Parthenopidae Family of Elbow Crabs. They are also known as the Baja cangrejo del codoin and the table top elbow crab and in Mexico as Baja cangrejo del codo.

Identification: The Baja Elbow Crab has a pentagonal shaped body and are normally colored to blend into their substrate within which they live. They have small eyes and are characterized by a pair of highly disproportionately elongated chelipeds (entire claws) that stick out from the sides of the body. The claws have an upper movable finger (dactyl) that is curved inwards toward the immovable lower finger and the inner surfaces have rows of colored bumps and spots that are believed to be used to startle prey. They are sexually dimorphic with the males being larger in overall size and with larger claws (chela) than the females. Their walking legs are thin and small and have pointed tips. The Baja Elbow Crab carapace reach a maximum of 15 cm (5.9 inches) in width and 11 cm (4.5 inches) in  length. The Baja Elbow Crab is very similar to and easily confused with the Slender Elbow Crab, Parthenope exilipes (longer arms; shell triangular, less ovate).

Habitat and Range:  The Baja Elbow Crab is  found within sandy, mud and rock bottoms at depths between 18 m (60 feet) and 73 m (240 feet).  In Mexican waters the Baja Elbow Crab is found at Magdalena Bay, Baja California Sur, southward along the southwest coast of Baja, throughout the Sea of Cortez and along the coast of the mainland south to Guatemala.

Diet:  They are slow moving and thus their prey is limited to small invertebrates including clams, snails and small worms. The Baja Elbow Crab is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

Conservation Status: From a conservation perspective the Baja Elbow Crab is currently considered as Data Deficient. They are small in stature, seldom seen by humans, and is of limited interest to most.

Synonyms:  Mesorhea gilli and Solenolambros belli.