Marine invertebrates including sea urchins, sea stars, corals, and molluscs face welfare considerations from collection, habitat degradation, and ocean acidification that deserve precautionary attention given scientific uncertainty about their sentience.
Marine invertebrate welfare occupies the most uncertain frontier in animal welfare science. For most species, the question of whether they have subjective experiences of pain or suffering is genuinely unresolved. The precautionary principle suggests that where evidence is uncertain and scales of impact are enormous, welfare consideration is warranted even without certainty. Sea urchins, sea stars, molluscs, and corals are exposed to a range of human-caused stressors — collection pressure, habitat degradation, acidification, temperature stress — that cause physiological harm regardless of subjective experience. Supporting marine conservation that reduces these stressors serves both clear ecological goals and precautionary welfare goals simultaneously.