01817nas a2200241   4500000000100000000000100001008004100002260001500043653002700058653002600085653002700111653002300138653002800161100001600189700001900205700001900224700002500243700001400268245004700282856004700329520118500376022001401561       2026                            d  c2026-08-3110aAnimal research ethics10aAnimal welfare policy10aInvertebrate sentience10aLaboratory animals10aPrecautionary principle1 aBob Fischer1 aMeghan Barrett1 aBrendan Parent1 aAlexandra K. Schnell1 aJeff Sebo00aEthical guidance for invertebrate research  uhttps://doi.org/10.1186/s13062-026-00963-53 aEthical oversight for animal research extends to vertebrates in most jurisdictions but excludes the vast majority of invertebrates—a taxonomic boundary that is increasingly difficult to justify given accumulating evidence of sentience in several invertebrate groups. This paper argues that researchers, institutions, and governments should develop voluntary best-practice guidance for invertebrate welfare as a practical and proportionate precautionary response, rather than waiting either for definitive proof of sentience or for formal regulatory solutions. We first review neurobiological and behavioral evidence for sentience in cephalopod mollusks, decapod crustaceans, and insects, concluding that a realistic possibility of sentience exists across all three groups. We then argue that a realistic possibility of sentience—rather than confirmation of sentience—is sufficient to warrant precaution, and show that this standard aligns with existing ethical frameworks in the UK, EU, and US. We further demonstrate that invertebrate use in research is substantial, with estimates ranging from tens of thousands of cephalopods and decapods to billions of insects annually.  a1745-6150