Coldwater Mole Crab

Coldwater Mole Crab, Emerita analoga

The Coldwater Mole, Emerita analoga, is one of four Mole Crabs found in Mexican waters, all belonging to the Hippidae Family known in Mexico as muy-muy cochitos. In Mexico they are known at muy-muy limanche. The Hippidae family is comprised of Emerita Genus and the Hippa Genus. Members of the Emerita Genus have a strongly convex oval shell or carapace that covers the legs, front legs without claws (nonchelated) and back legs (telson) that resemble paddles, long slender antenna and long slender eye stalks. Members of the Hippa Genus have a similar carapace, but front (nonchelated) and back legs that are slender and pointed, short stubby antenna and short stubby eye stalks. The Mole Crabs reside buried in sifting sand on wave-swept beaches in areas washed by waves. They bury themselves near the surface, facing seaward, with only their antennae and eyes out of the sand. They collect floating debris from wave draining off the beach with their first pair of legs, then transferring food to their mouths. They adapt to conditions of heavy surf and strong currents. In some places they are fairly abundant but difficult to observe because they blend into the background extremely well. Interestingly they reproduce based on food availability and not on tidal or water temperature changes. Although can be difficult to catch they are a favorite live bait of the Southern California surf fisherman but not utilized often as bait in Mexico.

The Coldwater Mole Crab are characterized by striations that run across the back half of their shells, their short paddle-like feet and short antennae and eyestalks. They reach a maximum length of 2.5 cm (1.0 inch) with females being about 30% larger than males. They can be easily confused with the Pacific Mole Crab, Hippa pacifica (differently shaped feet), the Striated Mole Crab, Hippa strigillata (different shaped feet and lines along the margins of the carapace) and the Tropical Mole Crab, Emerita rathbunae (lines covering the carapace completely). The Coldwater Mole Crab is a very common species that is found along the northwest coast of Baja southward to Guerrero Negro and in the middle third of the Sea of Cortez.

Coldwater Mole Crab, Emerita analoga. Collected by hand off the beach in the greater San Diego, CA area, August 2004. Size: 3.1 cm (1.2 inches) x 2.1 cm (0.8 inches).