Black spots on a Red Rock crab

Lets get one thing straight, the black spots on crab legs does not mean you have a diseased crab or a crab with cancer.

If you do a lot of crab fishing or cook with a lot of crabs you will sometimes notice that there are black spots, not just on the crab legs but on the larger main shell of the body as well. (It’s really noticeable on snow crab legs.)

We often get asked about black spots on crab legs and whether or not the meat inside is safe to eat.  Simply put, the answer is yes -ninety-nine percent of the time, the crab meat is perfectly safe to eat.

Here’s what happens:

Crabs are known fighters and stubborn as hell. They go to battle a lot. Some end up loosing a claw or leg, some end up with wounds. The wounds are similar to a bruise that we would get, only crabs don’t have skin they have an exoskeleton.

Also, crab shells get old. They don’t last the life of the crab.

Because crabs have an exoskeleton they shed (molt) their shell. Once they have molted they get a brand new shell, that is black spot free and ready for some fresh battles. 

If you find a crab that has black spots -it’s good news for you. It means that the crab hasn’t molted in a while and they are crammed full of meat. A shiny new shell might mean that there isn’e much meat on the inside.

Testing for a Soft Shell (recently molted)

On a Dungeness crab - check to see that the shell isn’t soft by pinching the bicep area of the crab claw. If the shell flexes you have a soft shell and should return it to the water.


What about the one percent that may not be safe?

Upon catching or before purchasing your crab make sure you do a full inspection of each spot. If there is a wound that made full penetration through the shell it’s a good idea to throw the crab back.

If you already have your crab at home before you noticed then you may want to cut the bruised meat away as it can a) look undesirable to eat and b) organisms may have entered the crab from this small hole.

Organisms gross!

Don’t fear, if an organism did find it’s way inside (even if you didn’t cut the bruised meat away) if you cooked your crab according to our cooking crab 101 guide then you don’t have any risk of anything terrible happening to you. Even if you already ate it and the said organism is…dare I say it…a worm. Blech!


What are the Black Spots on Crab Legs?
Crabs are known fighters and stubborn as hell. They go to battle a lot. Some end up loosing a claw or leg, some end up with wounds.
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Do you still have questions about black spots? Leave us your questions in the comments section below and we will be happy to answer them.

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