Bivalves are harvested in massive quantities globally. Their uncertain sentience creates an ethical puzzle about whether welfare considerations apply and what they would require.
Bivalve welfare sits at the philosophical boundary of where moral consideration begins. If sentience requires some degree of central nervous system integration and conscious experience, bivalves likely lack it. If welfare-relevant responses to noxious stimuli define the threshold, the evidence is more ambiguous - bivalves close their shells in response to stimuli but may lack any subjective experience of this. The precautionary principle suggests that under genuine uncertainty, avoiding harm is preferable to risking it. Practically, bivalve farming has such relatively low welfare risk per calorie compared to other animal protein sources that shifting consumption from vertebrate animal products to bivalves represents a likely welfare improvement, whatever the resolution of the sentience question.