Cancridae Latreille, 1802

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 227

Family Cancridae Latreille, 1802

The rock crabs, among the largest species of crabs in California or Oregon, have broad, oval carapaces and strong chelae. The front has several teeth, including a median tooth. The antennules fold back longitudinally. The antennal flagella are short and bear setae, especially in small animals. The third maxillipeds overlap the endostome. In many species, the ventrolateral parts of the body bear dense setae.

Species of cancrids inhabit both rocky and sandy bottoms, or areas of rocks lying among sand. Metacarcinus magister ( Rathbun, 1897) and M. gracilis (Dana, 1852) , which usually live on open sand, have especially flattened appendages with long dactyls. Other species tend to have more rounded appendages with shorter dactyls, which often bear stiff setae or spines. Metacarcinus magister is the object of a commercial fishery, primarily from San Francisco, California northward. Natural predators of cancrids include octopuses, large fishes and the sea otter. See Garth & Abbott (1980) for a lengthy account of the natural history of these crabs.

Until recently, the most comprehensive recent work on species of cancrids was that of Nations (1975). New morphological and molecular work by Schweitzer & Feldmann (2000) elevated the subgenera used by Nations to distinct generic status.

The key follows those of Schmitt (1921) and Rathbun (1930), but incorporates the recent changes in generic nomenclature. A carapace is said to be areolated if it displays prominent elevated areas. The guide by Phillips (1939) is useful for identification of larger species.