For humane purposes, a crab must be killed before cooking. Dropping a crab into boiling water alive causes the crab to suffer and its body to fall apart. In addition to the suffering, dropping a live crab into boiling water will make the meat tough and watery. If killed, then cooked, you will have a succulent meal to serve to your family or guests. The process to kill a crab requires minimal effort and there are two options available to maintain your comfort level during the process.
Place the live crab in enough fresh water to cover and leave it for approximately 30 minutes. The crab will essentially drown as it cannot survive in fresh water. This is not the most humane method of killing the crab; however, it is the least invasive method.
Turn the crab over on his back. You may wish to wear a glove while doing this to avoid being pinched by the crab.
Lift the triangular-shaped tail that points up to the crab's head. Continue lifting the tail away from the claws until it will not lift any further.
Insert a sharp chopstick or screwdriver into the small cone-shaped hole that is located under the tail.
Tap the end of the chopstick or screwdriver sharply with a rolling pin or other blunt object. This will kill the crab instantly.
Turn the crab over and allow it to drain completely. Once drained, the crab is ready to clean and then cook.