Cancer gracilis

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iCancer gracilis
Cancer gracilis caught in Southern California
Cancer gracilis caught in Southern California
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Family: Cancridae
Genus: Cancer
Species: C. gracilis
Binomial name
Cancer gracilis
Dana, 1852

Cancer gracilis or more commonly the graceful rock crab or slender crab is one of only two members of the genus Cancer whose chelae (claws) are white tipped, the other crab being C. magister (Dungeness crab). C. gracilis has been caught from Alaska to Vizcaino Bay, Baja California. Larvae and small juveniles of this species are often seen riding jellyfish, especially Phacellophora camtschatica. The juvenile crabs steal food from the jellyfish and also clean off parasitic amphipods.

[edit] Morphology

Like the other members of the family Cancridae, the slender crab has a very broad and oval carapace with dull tooth-like protrusions toward the front of the carapace. Female crabs can be distinguished from male by the broad tail flap on their undersides, which are used for protecting their eggs when they are gravid. The slender crab usually has a carapace that is olive brown and legs that vary from yellowish brown to purple. C. gracilis only grows to a width of about 3½ inches and so resembles a juvenile C. magister. Often the two species can be confused as C. gracilis looks very similar to a juvenile Dungeness crab. They can readily be distinguished from each other however by the appearance of hair on the posterior three legs of C. magister where C. gracilis is almost always hairless. Another telling characteristic of the slender crab is that the last segment of its tail flap is pointed, where C. magister is curved.