Pelagic Red Crab, Pleuronocodes planipes

Pelagic Red Crab, Pleuroncodes planipes. Crab collected off the surface with a bait net in coastal waters of the greater Los Cabos area, Baja California Sur,  April 2012. Size: 2.6 cm 1.0 inch) x 1.0 cm (0.4 inches).

The Pelagic Red Crab, Pleuroncodes planipes (Stimpson, 1860), is a member of the Munidae Family of Squat Lobsters that is also known as the Pelagic Red Crab, Red Crab, Tuna Crab and Lobster Krill, and in Mexico as langostilla and langosta pelagica.

The Pelagic Red Crab are small in stature with a long, sharp rostrum. Their clawed legs are long and slender and their carapace lacks spines. Their legs have short, dense hair. Overall they are orange to reddish-brown color with darker lines on the carapace. They reach a maximum of 10.0 cm (3.9 inches) in body length.

The Pelagic Red Crab is normally found over sand and mud substrates at depths between 50 m (165 feet) and 365 m (1,800 feet), however they can occasionally be found on the surface. They feed on copepods, detritus and diatoms utilizing the hairs on their legs to filter food from the water. They are very abundant and a critical food source for a wide variety of fish, pinnipeds, squid, sea turtles, baleen whales, and sea birds. At times, they comprise 85% of the diet of Yellowfin Tuna. There is even an endemic species, the Fish-eating Bat, Myotis vivesi, that feeds on these animals. Pelagic Red Crabs spend their larval phase and the first year of their life as plankton. They ride the California Current far out to sea and then return to the continental shelf by riding a deeper counter current. They swim well enough to be able to vertically migrate to feed, swarm, and mate at shallow depths. They are known to be “beached” and become stranded in groups numbering hundreds of thousands during high wind episodes.

The Pelagic Red Crab is a resident of all Mexican waters of the Pacific with the exception that they are absent from Guerrero Negro, Baja California, northward along the central and northwest coasts of Baja.

From a conservation perspective the Pelagic Red Crab has not been formally evaluated. On rare occasions they can be collected off the ocean surface with a bait net. Also on rare occasions they are sold by the commercial bait salesmen, sourced from the greater Magdalena Bay area, of the greater Los Cabos area as a live bait. They are utilized as a premier live bait targeting bottom fish and specifically the Pacific Red Snapper. On one or two occasions I have seen them herded into surface balls and literally all hell has broken loose with with a wide range of predators engaging in massive feeding frenzies.