Filter-feeding bivalves like oysters and clams are farmed at enormous scale. Their sentience is considered unlikely but the precautionary principle and ecological role of their farming practice shape welfare considerations.
Bivalves lack a centralized brain; their nervous system consists of ganglia that coordinate reflexes and feeding. The Cambridge Declaration on Consciousness did not include bivalves in its list of likely sentient animals. The primary welfare-relevant consideration for farmed bivalves is the ecological health of their farming environment. Bivalve farming generally improves water quality through filter-feeding; it is one of the most environmentally positive animal protein sources. Consumer interest in bivalves as a low-welfare-impact animal protein source is growing among environmentally conscious eaters.