Spiders are among the most numerous predatory animals on Earth, and growing evidence of nociception in arachnids raises questions about their moral status and how humans treat them.
Spider welfare occupies the furthest reaches of current welfare consideration — their neurology differs fundamentally from vertebrates, making confident claims about conscious experience very difficult. However, evidence of nociceptive responses, complex behaviour and sophisticated cognition in some species like jumping spiders warrants at least precautionary consideration. The practical welfare question for most people is simpler: spiders encountered in homes cause no harm and consume insect pests — killing them is both unnecessary and deprives a beneficial predator of its life. Relocating spiders outdoors rather than killing them is a low-cost welfare choice. As invertebrate welfare research develops, spider welfare will likely receive more formal attention.