Metacarcinus magister  (Dana, 1852) Schweitzer and Feldmann, 2000 Common Name:  Dungeness Crab, Market Crab, Common Edible Crab
Synonyms:  Cancer magister
Phylum Arthropoda   Subphylum Crustacea    Class Malacostraca     Subclass Eumalacostraca      Superorder Eucarida       Order Decapoda        Suborder Pleocyemata         Infraorder Brachyura         Superfamily Cancroidea           Family Cancridae
	Figure 1.  Top and bottom view of Metacarcinus magister.  Approximately 20 cm carapace width.  Collected at Padilla Bay, WA.
	Photo by:  Janisse Maxwell, taken 6-02.

How to Distinguish from Similar Species:  A similar, somewhat larger crab is the Furrowed Rock Crab (Romaleon branneri).  This species is not common in the intertidal region, unlike M. magister, and differs in that the dactyls of its chelae have black tips and spines that  line the upper margin of the movable finger of the claws.  Cancer productus, often found in the intertidal in the Pacific Northwest, also has black tips to the dactyls of the chelae.  Metacarcinus gracilis has a distinct tooth behind the widest point of the carapace and has no spiny ridges on the carpus, propodus, and dactyl of the chelae.

Geographical Range:  Occurs from Alaska to Santa Barbara, California.

Depth Range:  Lives intertidally to a depth of 230 m.

Habitat:  Most common in sand or muddy-sand bottoms in subtidal regions, but are often found in or near eelgrass beds.

Biology/Natural History:  This crab is the largest edible crab from Alaska to California, making this species important for fisheries commercially and economically.  There appears to be five subspecies in California alone.  The female Dungeness crab can lay up to 2.5 million eggs and can live up to at least 6 years.  Females can store sperm received during one mating season and use it during the next season.  This species is a carnivore that feeds on more than 40 different species including small clams, oysters, fish, shrimp, worms and according to recent studies even feeds on Velella nematocysts.  The larvae of this species is often attached to the bells of jelly fishes and to their tentacles; these larvae feed on the gonozooids, and by doing so gain protection from pelagic fish predators and are transported to juvenile crab habitats nearshore as long as associated with the cnidarian.  Dungeness crab larvae feed primarily on zooplankton, however phytoplankton are also eaten.  The larvae are crepuscular migrators, being found near the surface at dawn and dusk but deeper in midday and midnight.  The stage 1 zoeae are nearest the surface with later zoeal stages in deeper water.  In spring, larvae of this species may be advected north along the coast as far as Alaska (Park et al., 2007).  In springtime, adults of this crab can be found buried in sand or in tidepools, where it can hide and wait for its new shell to harden.  On average, males will cover more ground in an hour than females, and ovigerous females move less than nonovigerous females or males.  Near Vancouver Island, adults have more epibionts than do juveniles (McGraw, 2006).  Common epibionts include barnacles (especially Balanus crenatus) on the dorsal surface, green, red, and brown algae (especially on the antennae), tube-dwelling polychaetes (mainly on the ventral surfaces), hydrozoans (mainly on ventral surfaces and limbs), bryozoans (especially Membranipora membranacea) on any region of the carapace.  A few had sponge, tunicate, or mollusk epibionts.

General References:
  Kozloff, 1993.
  Morris et al., 1992.
  Sept, 1999.

Scientific Articles:

Airriess, C., and McMahon, B., 1994.  Cardiovascular Adaptations Enhance Tolerance of Environmental Hypoxia in the crab Cancer magister. Journal of Experimental Biology 190:  23-41

Bernatis, J., Gerstenberger, S., McGaw, I., 2007.  Behavioural responses of the Dungeness crab, Cancer magister, during feeding and digestion in hypoxic conditions. Marine Biology, Vol. 150, pp. 941-951

Graham, R., 1985.  A model for L-lactate binding to Cancer magister hemocyanin. Comp .  Biochem. Phys., Vol. 81, pp. 885-887

Hankin, D.G., N. Diamond, M.S. Mohr, and J. Ianelli, 1989.  Growth and reproductive dynamics of adult female Dungeness crabs, Cancer magister in northern California.  Journal du Conseil Permanent International pour l'Exploration de la Mer 46: 94-108

Hobbs, R.C. and L.W. Botsford, 1992.  Diel vertical migration and timing of metamorphosis of larvae of the Dungeness crab, Cancer magister.  Marine Biology 112: 417-428

Jensen, P.C., J.M. Orensanz, and D. Armstrong, 1996.  Structure of the female reproductive tract in the Dungeness crab (Cancer magister) and implications for the mating system.  Biological Bulletin 190: 336-349

Lough, R.G., 1976.  Larval dynamics of the Dungeness crab, Cancer magister off the central Oregon coast, 1970-71.  Fish. Bull. 74: 353-375

McConnaughey, R.A., D.A. Armstrong, B.M. Hickey, and D.R. Gunderson, 1994.  Interannual variability in coastal Washington Dungeness crab (Cancer magister) populations:  Larval advection and the coastal landing strip.  Fish. Oceanogr. 3: 22-38

McGaw, I., 2005.   Burying behavior of two sympatric crab species: Cancer magister and Cancer  productus. Scientia Marina, Vol 69, pp. 375-381

McGraw, Iain J., 2006.  Epibionts of sympatric species of Cancer crabs in Barkley Sound, British Columbia.  J. Crustacean Biology 26:1 85-93

Park, Wongyu, David C. Douglas, and Thomas C. Shirley, 2007.  North to Alaska:  Evidence for conveyor belt transport of Dungeness crab larvae along the west coast of the United States and Canada.  Limnology and Oceanography 52:1 248-256

Shirley, T.C. and L. McNutt, 1989.  Precocious molting and trans-molt sperm retention by female Dungeness crabs.  American Zoologist 29: 131A

Stillman, Jonathon H., John K. Colbourne, Carol E. Lee, Nipam H. Patel, Michelle R. Phillips, David W. Towle, Brian D. Eads, Greg W. Gelembuik, Raymond P. Henry, Eric A. Johnson, Michael E. Pfrender, and Nora B. Terwilliger, 2008.  Advances in crustacean genomics.  Integrative and Comparative Biology 48:6 pp 852-868

Thomton, Jamie D., Sherry L. Tamone, and Shannon Atkinson, 2006.  Circulating ecdysteroid concentrations in Alaskan dungeness crab (Cancer magister).  Journal of Crustacean Biology 26:2 pp 176-181

Sulkin, S. and G.L. McKeen, 1989.  Laboratory study of survival and duration of individual zoeal stages as a function of temperature in the brachyuran crab Cancer magister.  Marine Biology 103: 31-37

Another photo of Metacarcinus magister, by Dave Cowles

The many barnacles encrusting this individual, found in a tidepool at Kalaloch in 2009, implies that it has been some time since the animal has molted.  These crabs spend a significant amount of time buried in the sand with only their face projecting.  This fact can be seen in this individual by noting that the barnacles do not encrust the back end, which is usually buried and without access to oxygen or food, but do encrust the front end which projects from the sand.  Photo by Dave Cowles, July 2009