https://www.lse.ac.uk/News/Latest-news-from-LSE/2021/k-November-21/Octopuses-crabs-and-lobsters-welfare-protection

Led by researchers from the London School of Economics and Political Science (LSE), the review established eight criteria by which animal sentience can be established. Looking at over 300 scientific studies the report established a confidence level for each criteria, spanning from no confidence to very high confidence.

“On our scheme, high or very high confidence that an animal satisfies seven or more of the criteria amounts to very strong evidence of sentience,” the report states. “High or very high confidence that an animal satisfies five or more criteria amounts to strong evidence of sentience, and high or very high confidence that an animal satisfies three or more criteria amounts to substantial evidence of sentience.”

The highest estimation of sentience was seen in octopuses, with high or very high confidence in seven of the eight criteria. The lowest rating was measured in nautiloids (and penaeid prawn)…only fulfilling high confidence in one of the eight criteria…and thus, as such, can be considered substantial evidence of non sentience…