How growing evidence for invertebrate sentience is expanding the moral circle and changing welfare practice.
The expanding moral circle — the progressive inclusion of more taxa in our ethical concern — has reached invertebrates with new urgency as scientific evidence accumulates. The case for octopus and crab sentience is now strong enough to have influenced law in multiple jurisdictions. For insects and other smaller invertebrates, the evidence is more uncertain but the precautionary principle combined with the enormous scale of invertebrate farming and killing suggests that even modest probability of sentience demands attention. Welfare science must engage with invertebrate welfare proactively rather than waiting for certainty that may never fully arrive.