| Has two migrations, mating-molting and feeding migration (Ref. 78813). This is the most valuable commercial crab on the Pacific coast of North America (Ref. 865). Maximum depth from Ref. 121573. This is a benthic species. The crab is confined mainly to sand-and-pebble bottom. It prefers areas of hard bottom and thickets of macrophytes (Ref. 121573). At summer time, adult and juvenile distribute in mostly shallow shelf less 100 m. Non-migratory juveniles stay in one area throughout the year. Adults overwinter at depths of 150-300 m. Their cyclic migrations are from shallow waters to deep waters and vice versa. At each season they choose the most favorable feeding conditions, shelters for molting and suitable hydrological conditions for life. At spring, adults migrate from depths to shallow waters of 2 to 9 m for spawning: larvae hatching from mature external eggs, females molting in the presence of males and then mating (Ref. 121574). The molting process lasts 4-10 minutes. Curing of the shell lasts about 2-3 days, during which two missing layers of the shell are formed. Contamination degree of the shell allows to determine whether the crab has molted in the present or last year. Particularly, the ventral view of the shell is contaminated and erased intensely (Refs. 121580, 121581). After spawning or molting, the crabs spend the remainder of summer and whole autumn to feed. Usually the crabs move zigzag between forage places at an average speed of 1.4-2.3 km per day (Refs. 121582, 121583). Feeding migrations are dependent on two factors: distribution of forage places and the water temperature (Ref. 121584). Both an opportunistic and a generalist predator. A number of studies revealed that,, when introduced to new virgin areas, the species prefers preying on large specimens of benthic animal groups such as bivalves, echinoderms, and sipunculids (Ref. 113901). Adults mainly feed on mollusks, crustaceans and polychaetes. In addition, its regular prey are echinoderms, sponges, rhizopods, bryozoans and algae. The average daily diet of adult over 150 mm in size is 0.8% of its body weight. No differences in food preference were found between male and female crabs. Juveniles feed on ophiuroids, sponges, bivalves, as well as polychaetes and barnacles. The diet of juveniles with a carapace width of 2-20 mm is poorer than that of an adult's, and it is characterized by a large abundance of sponges and hydroids (Ref. 121579). These crabs exhibit cannibalism (Ref. 101157). |