Octopuses are the most cognitively sophisticated invertebrates known, with distributed intelligence across their arms and remarkable problem-solving abilities. Their inclusion in the UK Animal Welfare Act in 2022 represents a landmark recognition of invertebrate sentience.
Octopus welfare in captivity and research settings has received growing attention since their sentience recognition. Research octopuses are held in aquaria and subjected to experimental procedures — handling stress, novel environment exposure, and in some cases surgery — that carry welfare risks given their established cognitive complexity. Best practice guidelines for cephalopod welfare in research have been developed by the European Directive on cephalopod welfare. Octopuses in home aquariums face stress from small tanks, lack of environmental complexity, and inappropriate lighting conditions. Wild octopuses face threats from bycatch, habitat degradation, and climate-driven ocean acidification. The welfare recognition of octopuses represents an important step in extending the moral circle to invertebrates with demonstrated cognitive sophistication.