The red rock crab is a hunting species of crab that actively forages in the intertidal zone, often excavating to find its prey (Smith et al. 1999). Foraging occurs most often in shoreline areas protected from wave action (Robles et al. 1989). Males forage most often during the day, while females forage more commonly at night (Robles et al. 1989). Diet includes clams, barnacles, smaller crabs, amphipods, sea cucumbers, polychaetes, other intertidal invertebrates and dead fish (Cowles 2005). As with other species, males will guard females during the molt, protecting them until their exoskeleton hardens--mating occurs after the molt. (Cowles 2005). Predators include bass and sculpin (on juveniles) and seabirds--this species is reported to be a favourite prey item of the giant Pacific octopus (Cowles 2005, Wikipedia 2010). Recent research has shown that, while adults are fairly uniform in colour (primarily dark reddish with white spots), juveniles show a remarkable array of colours and shell patterns, which may reduce visibility to predators (Krause-Nehring et al.2010). There is no commercial fishery for this species in BC.
View a photo of the colour variation in juveniles of this species.