Shellfish, like all proteins, have a shelf life and require proper refrigeration. Take precautions with your shellfish – as you do meats, fish, eggs and poultry – to reduce the risk of food-borne illness.
Live oysters, clams and mussels should close their shells when handled. Tap any open shells firmly a few times. If the shell closes, the shellfish is still alive. Discard animals with broken shells or shells that do not close when tapped.
Fresh Shellfish (Shucked)
Source: BC Centre for Disease Control