Rock & Red Crabs: The Pacific's Other Crab:
When you think of crabs on North America's West Coast, you think of Dungeness crab, the giant, meaty crustacean that is the vital ingredient in cioppino and several other Western classics. But the Dungeness lives with two other crabs: The Pacific red crab and its cousin the rock crab.
All live in and around rocky places -- thus the name "rock crab" -- and all are walking crabs, meaning their last set of legs is pretty much like the rest. In Eastern blue and calico crabs, the final set of legs have flippers; these are swimming crabs.
Of the two, red crabs are the most, well, crabby. They are mean and will pinch you. Rock crabs are more docile. As with all crabs, you can tell the male from the female by the plate underneath the body: it is narrow in the male, wide in the female. The roe, bright orange stuff inside the female, is delicious and is a critical ingredient in she-crab soup. Some people also eat the green "mustard" inside the body; this is the liver.
In both species, most of the meat is in the giant crusher claws these critters are armed with. They are virtually identical to the famed Florida stone crabs, so you can substitute red or rock crabs in any stone crab claw recipe you find.
These crabs will grow to more than 10 inches across, but 4-6 inches is more common. You will most often find them in Asian markets: Commercial catches of these crabs are minor compared to those of the Dungeness. But, if you catch your own crabs, know that they are every bit as tasty as Dungeness.
The main reason for their second-fiddle role is because they are smaller than Dungeness. The body meat in rock and red crabs is also more difficult to extract than that in Dungeness crabs -- they do not give up their treasures lightly.
My advice if you come across a mess of red and rock crabs is to cook the claws like stone crabs -- boiled in a seasoned broth and eaten with butter or mayo -- then use the bodies of all but the largest crabs to make stock or sauces.
Cracking the legs and the cleaned bodies of these crabs will give you the fixings for an outstanding tomato-based spaghetti sauce. This sauce doesn't reheat well (like many seafood dishes), so if you have lots of crabs at once, store the cooked bits in a bag and freeze until you want to make the sauce again.
If you are fortunate enough to get a hold of large red and rock crabs, meaning the shell is wider than 6 inches, treat them as Dungeness and pick out all the meat for any crab recipe that suits your fancy.