Invertebrates such as octopuses, crabs, and crayfish are increasingly recognized as sentient beings capable of experiencing pain. Laboratory welfare standards are slowly expanding to include these animals.
The exclusion of invertebrates from mainstream animal welfare regulation reflects historical assumptions about their sentience rather than scientific evidence. Mounting research on pain processing in crustaceans and cephalopods challenges the idea that these animals do not suffer. Laboratory environments for invertebrates often lack enrichment, appropriate social conditions, or space — even when these factors are known to affect behavior and physiology. Expanding regulatory protection and developing welfare assessment tools for invertebrates is one of the emerging frontiers in laboratory animal ethics.