Marine invertebrates including crabs, lobsters, octopuses, sea urchins, and starfish occupy a wide spectrum of neural complexity. Growing evidence of pain-like states in some species is reshaping how we think about their welfare in fisheries and aquaculture.
Marine invertebrate welfare has moved from a fringe concern to mainstream policy debate as evidence of sentience accumulates. For decapod crustaceans, physiological and behavioural evidence suggests they experience a pain-like state when exposed to noxious stimuli, including wound guarding, avoidance learning, and analgesic responsiveness. Octopuses demonstrate sophisticated problem-solving, play behaviour, and individual personalities suggesting rich inner lives. The welfare implications extend across commercial fisheries, live transport, restaurant practices, and scientific research. Transitioning to humane kill methods is technically feasible and increasingly required by law in some jurisdictions. Greater recognition of marine invertebrate sentience requires parallel advances in understanding their welfare needs in captive research and aquaculture contexts.