Marine invertebrates including corals, sea urchins, and starfish face growing threats from climate change and fishing. Their welfare status is uncertain but conservation interventions benefit their populations.
Marine invertebrate welfare occupies the most uncertain territory in welfare science. Most marine invertebrates lack the neural complexity that neuroscientists associate with conscious experience — they have no centralised brain and limited learning capacity. The welfare case for their protection is therefore primarily conservation-based rather than individual sentience-based: protecting coral reef ecosystems protects the millions of fish and crustaceans that depend on them and whose welfare is less uncertain. However, for marine invertebrates with more complex nervous systems — some cephalopods and possibly some echinoderms — more uncertainty exists, and the precautionary principle applies.