Pacific Sand (Mole) Crab

Emerita analoga

Order: 

Decapoda

Family: 

Hippidae

The Emerita analoga is commonly referred to as the sand crab or mole crab.  While the geographic distribution ranges from Alaska to Baja California, the general habitat remains the rocky intertidal zone.  Carapace length within adults get up to 35mm while the body size of larvae ranges from 0.7-3.5mm.  As larvae, the E. analoga are filter feeders while as adults, the crabs feed on various plankton.  In contrast, predators include birds, fishes, and other mammals.  Fun facts include that many neurological studies utilize the adults because the crab tail has the largest sensory neurons found in any animals.  Another fact is that the adult crabs lack claws or spines but have antennae that permit the crabs to gather food in addition to oxygen (1).  The particular species is one of the most common within the rocky intertidal zone with approximately 79,000 individuals per meter of shoreline.  As larvae, the mole crabs have large dispersal capacities because of the 3-4 month long planktonic larvae stage.  After the planktonic phase, recruitment occurs from April to November throughout California.  Variation in respect to size and age at maturity vary substantially with latitude (2).

 

(1) Johnson, M.W., and Weldon, M.L. (1942) Pelagic larval stages of the sand crabs Emerita analoga (Stimpson), Blepharipoda occidentalis Randall, and Lepidopa myops Stimpson. Biological Bulletin 83: 67-87.

(2) Dawson, M. N., J. L. Staton, and D. K. Jacobs. 2001. Phylogeography of the tidewater goby, Eucyclogobius newberryi (Teleostei, Gobiidae), in coastal California. Evolution 55:1167–1179.

Habitat:

  • Rocky Intertidal Zone