1, 20 minutes or so. Grape head sea crab can be cooked in about 20 minutes, but the kind of larger crabs should be cooked for a longer time.

2, not sure whether to cook can be observed whether the color of the crab crustacean red, if it is red that has been cooked. In order to prevent the loss of too much yellow paste when cooking sea crabs, steaming can be its abdomen upward.