Spiders and other invertebrates are rarely considered in welfare discussions, but growing evidence of their behavioral complexity raises questions about their capacity for relevant experiences.
Welfare consideration for spiders and other invertebrates sits at the frontier of welfare science. Current evidence does not definitively establish sentience in spiders, but behavioral complexity and learning capacity suggest they are not simply stimulus-response machines. The precautionary approach suggests treating animals with uncertain sentience with reasonable consideration rather than assuming the absence of welfare significance. For most practical purposes this means avoiding unnecessary harm where alternatives exist.