This crab, one of the 35 true crabs living in Canadian Pacific waters. A male crab can grow to a maximum width of 23 cm and weigh about 2 kg. The main colour of both sexes when alive is a blend of brown and tan. The Dungeness crab, however, is distinguished from the red crab by its slender, light-coloured fingers of the claw, and from the graceful crab by the normally 10 teeth along the lateral margin of the shell, and broad flat walking legs.
Sport fishermen catch the red rock crab.
During breeding, the male crab clasps the female so that the undersides of each are in close contact. Breeding actually lasts less than 30 minutes, but a male may transport his partner about for several days prior to her moulting. Eggs are not fertilized and spawned until autumn, the sperm remaining viable since the summer breeding. There is evidence that the sperm supply is sufficient to fertilize a second batch of eggs. After fertilization, eggs, estimated at half a million to a million, are extruded and are attached to the female's abdomen where they are brooded until spring.