So remember to plan for this in your cooking time. Shellfish should be cooked until it becomes opaque throughout - it will not flake. Additional cooking will give you a tough product with a less desirable taste and texture. Shucked oysters and clams are done when their edges curl. Shrimp and lobster turn red and the flesh becomes purely opaque.
Scallops turn opaque and firm.
Discard those that stay closed. A photograph is available on our web site by Clicking Here.