Invertebrates make up the vast majority of animal species and are increasingly featured in zoos - while their sentience is uncertain, welfare-conscious exhibit design reflects scientific uncertainty appropriately.
Zoo invertebrate welfare operates under significant scientific uncertainty about sentience, but precautionary approaches recommend providing appropriate environments regardless. The precautionary principle suggests that where we cannot rule out suffering, we should minimise potential harm. For cephalopods like octopuses, welfare evidence is substantial enough to warrant specific enrichment requirements in many jurisdictions. Exhibit design should prioritise species-appropriate conditions - temperature, humidity, substrate, space and enrichment - based on natural ecology. Conservation breeding programs for threatened invertebrates like the Partula snail and Lord Howe Island stick insect demonstrate the zoo sector's valuable contribution.