About Metacarcinus gracilis (Dana, 1852)
Like other members of the family Cancridae, the slender crab (Metacarcinus gracilis) has a very broad, oval carapace with dull tooth-like protrusions on the front portion of the carapace. Females can be told apart from males by their broad tail flap on the underside, which protects eggs when the crab is gravid. The carapace of M. gracilis is most often olive brown, while its legs range in color from yellowish brown to purple. M. gracilis only grows to a carapace width of about 3.5 inches (9 cm) and resembles juvenile Metacarcinus magister, the Dungeness crab. The two species are often confused due to this strong similarity, but they can be easily distinguished. M. gracilis has a notch behind the widest point of its carapace that M. magister does not have, and the top joint of its pincers lacks the serrations seen on M. magister's pincers. A less obvious distinguishing trait is that M. magister has hair on its posterior three legs, while M. gracilis is almost always hairless on these legs. Another clear identifying characteristic is that the last segment of M. gracilis's tail flap is pointed, while the corresponding segment in M. magister is curved.
