The welfare of aquatic invertebrates is a growing area of scientific and ethical inquiry, with evidence suggesting that many species have more complex experiences than previously assumed.
Aquatic invertebrate welfare exists on a spectrum of moral uncertainty, with strong evidence for sentience in cephalopods and growing evidence in decapod crustaceans, while the case for bivalves remains genuinely uncertain. A welfare-conscious approach applies precautionary principles proportional to the probability of sentience — treating cephalopods with high welfare consideration, extending meaningful consideration to lobsters and crabs, and remaining open to evidence as it develops for bivalves. The enormous numbers of invertebrates consumed globally means that even low probabilities of sentience translate to potentially enormous welfare impacts. Research investment in invertebrate sentience remains far below its ethical importance.