Red rock crabs live in a very diverse environment and it's either eat or get eaten. They are a fairly aggressive species and will look for pretty much anything to eat when given the chance. They are often hidden under rocks but have sensitive chemoreceptors as well as compound eyes on elevated stalks and several light sensitive eye spots to spot predators and prey. Predators include sand and kelp bass, among other fish, seabirds such as gulls and pigeons. They are a main food source of the endangered sea otter Enhydra lutris.



Prey include barnacles and smaller crabs, amphipods, sea cucumbers, polychaetes, many other intertidal invertebrates, as well as dead fish. Red rock crabs often feed on the invasive green crab (Carcinus maenas).They are also a threat to commercial oyster beds if safety precautions such as laying a predator exclusion netting are not used. Larva will feed on plankton and other microscopic organisms.



To learn about what they do after they catch their food click here.


Other Interactions

They share a symbiotic relationship with several species of barnacles as well as sponges. The barnacle is able to filter-feed as the crab moves around. The crab receives protection from the barnacle as camouflage and sometimes they will crush the barnacles to eat.

They may host parasitic nematodes of the genus Carcinomertes found under the legs. These worms appear as small reddish spots and can be a threat to the eggs if a female is carrying. They may also have a relationship with tube-dwelling polychaetes on the ventral surfaces, hydrozoans on ventral surfaces and limbs, and bryozoans on any region of the carapace.




To learn some interesting facts about the red rock crab click here!

To go back to the home page click here!