Panamic Spider Crab, Maiopsis panamensis

Panamic Spider Crab, Maiopsis panamensis. Provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, March 2011. Size: 15.5 cm (6.1 inches) x 15.5 cm (6.1 inches); Wing Span: 60 cm (23.6 inch). Identification reconfirmed by Dr. Greg Jensen, Seattle, Washington. The claw was collected off the beach at Punta Lobo, Baja California Sur. Leg size: approximately 30 cm (12 inches) indicative that this specific individual had a wing span of approximately 93.5 cm (3 feet 1 inch).

General information:  The Panamic Spider Crab, Maiopsis panamensis, is a brachyuran crab and a member of the Majidae Family, which includes the spider crabs that are known in Mexico as cangrejos. It is known locally as cangrejo araña de Panama. They are not well known and rarely studied. Although first reported off the coast of Panama in 1893, the Panamic Spider Crab was not reported in Mexican waters until 1979. Reproduction occurs during November and December with the eggs being incubated via attachment to the female abdomen from spawning to hatching.

Identification:  The Panamic Spider Crab is a bright red decapod with very long legs and an oval-shaped body. They have eyes on short stalks, a broad flattened carapace (shell), a small abdomen folded under the thorax, and long arms with big pincers. The Panamic Spider Crab is the largest of the brachyuran crabs with a shell a 25 cm (10 inches) and “wing spans” that approach 1.4 meters (4 feet 6 inches)! The larger males, that can weigh up to 3.9 kg (8 lbs 8 oz) are more abundant and much larger than the females, to 1.4 kg (3 lbs 0 oz). The Panamic Spider Crab can be confused with the much smaller Velvet Spider Crab, Stenocionops ovata (about one-third of the size).

Habitat and Range:  The Panamic Spider Crabs are found at depths between 15 m (50 feet) and 305 m (1,000 feet), over a variety of substrate.  The Panamic Spider Crab range from Topolobampo, Sinaloa, Mexico, to Caleta La Cruz, Peru. The collection of photographs above document a range extension for this species into the Pacific ocean along the southwest coast of Baja. Spider crabs are caught frequently as a by-catch by shrimp trawlers.

Diet:  Panamic Spider Crabs are omnivorous scavengers that feed on decaying fish, other invertebrates and algae.

Conservation Status:  From a conservation perspective the Panamic Spider  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.