Mating Behavior in the Spider Crab, Chionoecetes opilio

During the week-long precopulatory embrace, the male spider crab, Chionoecetes opilio, held the female, even when attacking intruding males. Before a 45-min copulation period the male assisted female ecdysis. During the postcopulatory embrace spermatophores flowed onto the pleopods of the female. Polygamous males as small as 60 mm width mated with larger females. More than one fertile egg batch was frequently produced from one mating. Females mated successfully up to 95 hr after molting. Hard-shelled females seemed incapable of mating. The probable mating season is February through April and continued recruitment seems assured.