Biology/Natural History: This crab is the largest edible crab from Alaska to California, making this species important for fisheries commercially and economically. There appears to be five subspecies in California alone. The female Dungeness crab can lay up to 2.5 million eggs and can live up to at least 6 years. Females can store sperm received during one mating season and use it during the next season. This species is a carnivore that feeds on more than 40 different species including small clams, oysters, fish, shrimp, worms and according to recent studies even feeds on Velella nematocysts. The larvae of this species is often attached to the bells of jelly fishes and to their tentacles; these larvae feed on the gonozooids, and by doing so gain protection from pelagic fish predators and are transported to juvenile crab habitats nearshore as long as associated with the cnidarian. Dungeness crab larvae feed primarily on zooplankton, however phytoplankton are also eaten. The larvae are crepuscular migrators, being found near the surface at dawn and dusk but deeper in midday and midnight. The stage 1 zoeae are nearest the surface with later zoeal stages in deeper water. In spring, larvae of this species may be advected north along the coast as far as Alaska (Park et al., 2007). In springtime, adults of this crab can be found buried in sand or in tidepools, where it can hide and wait for its new shell to harden. On average, males will cover more ground in an hour than females, and ovigerous females move less than nonovigerous females or males. Near Vancouver Island, adults have more epibionts than do juveniles (McGraw, 2006). Common epibionts include barnacles (especially Balanus crenatus) on the dorsal surface, green, red, and brown algae (especially on the antennae), tube-dwelling polychaetes (mainly on the ventral surfaces), hydrozoans (mainly on ventral surfaces and limbs), bryozoans (especially Membranipora membranacea) on any region of the carapace. A few had sponge, tunicate, or mollusk epibionts.
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