Scientific evidence on bivalve sentience is developing. Understanding what we know and do not know guides precautionary welfare standards for oysters, mussels, and clams.
The evidence for bivalve sentience remains genuinely uncertain. Behavioural responses to damaging stimuli are consistent with nociception but do not definitively demonstrate conscious pain experience. The lack of centralised brain structures associated with conscious experience in vertebrates makes extrapolation difficult. However, the precautionary principle applied in UK welfare legislation for decapods could reasonably extend to bivalves given uncertainty. Applying minimal welfare standards to handling and slaughter, such as minimising air exposure and transport stress, imposes low cost while hedging against uncertain welfare risk.