Personality dimensions in the common octopus(Octopus vulgaris)

Understanding the origin, universality, and maintenance of among-individual variation in behaviouris a current focus of behavioural ecology and comparative psychology. Research on animal person-ality emphasising the central role of the individual contributes to conservation efforts and animalwelfare by tailoring guidelines and interventions at the individual level. Cephalopods are under-studied in this respect, despite being the only invertebrate group currently included in internationaldirectives for the protection of animals used for scientific purposes. Here, we assessed among-individual variation in behavioural responses (i.e., animal personality) of 21 common octopuses(Octopus vulgaris) temporarily kept in captivity. We performed a battery of tests across threedifferent experimental contexts, namely a Startle test, a Foraging test, and a Disturbance test,each repeated for four consecutive days, adapting established protocols from other cephalopods.Behavioural variables were moderately repeatable. Results of a principal component analysisrevealed a three-component structure, with components we labelled Alertness, Exploration, andBoldness. The components were also moderately repeatable. The components Exploration andBoldness predicted each other across experimental contexts, suggesting a behavioural syndrome.Overall, findings indicate marked individual differences in common octopuses, and provide evi-dence of personality dimensions in a widely used animal model in neurophysiology and cognition.Our findings thus contribute to the study of the evolution of personality structure from a compara-tive perspective, and may help individual-level welfare refinement.