Invertebrates in zoos are increasingly recognized as animals with potential welfare needs, though uncertainty about their sentience makes welfare assessment challenging. The precautionary approach is gaining ground.
Invertebrate welfare in zoos sits at a fascinating ethical frontier where scientific uncertainty about sentience meets growing evidence of complex behavior and potential pain experience. The precautionary welfare principle argues that uncertainty about whether an animal can suffer is not permission to ignore that possibility, particularly when the probability is non-trivial and interventions to improve welfare are available. For cephalopods especially, the evidence of complex cognition, sophisticated problem-solving, and behavioral indicators consistent with stress and pain is substantial enough to warrant serious welfare consideration. Octopuses in inappropriate housing - inadequate space, no hiding areas, cohabitation - show behavioral indicators of chronic stress that should not be dismissed simply because we cannot be certain of their subjective experience.