130 | Behavioural taxonomy of the common octopus: a framework for understanding individual variation through complex task navigation

Emanuela Cirillo^1|2, Tania Russo³, Mariangela Norcia¹, Valeria Maselli¹, Salvatore Valiante¹, Michael Kuba¹, Marco Gamba⁴, Gianluca Polese^1|2, Anna Di Cosmo^1|2 | ¹Dipartimento di Biologia, Università di Napoli Federico II, Napoli, Italy; ²MNESYS - PNRR partenariato esteso; ³Dipartimento di Biologia, Ecologia e Scienze della Terra, Università della Calabria, Rende (CS), Italy; ⁴Dipartimento di Scienze della Vita e Biologia dei Sistemi, Università di Torino, Italy.

Behavioural taxonomy provides a powerful framework for understanding how the diverse behavioural repertoires of animal species expressed through strategies of foraging, mating, and social interaction drive adaptation to environmental change and are fundamental to conservation and animal welfare. Octopus vulgaris, with its centralized brain, jointless arms, and highly distributed peripheral nervous system, represents a unique biological model for investigating behavioural variation across individuals, populations, and species within their ecosystem. In this study, we investigate behavioural biodiversity (etho-diversity) in octopus problem-solving tasks. For this purpose a device designed for a multisensory task, reassembling the natural exploration, decision-making, and arm-based control was built. It consists in three-choice device that provides visual access to multiple targets while restricting physical interaction to narrow access ports, thereby requiring active arm exploration and manipulation. Eight wild-caught adult males were tested in agreement with the animal welfare regulation. The experimental protocol included a pre-training phase to establish the device reward contingency, followed by a discrimination task involving a real prey item and visually identical, non-edible 3D-printed replicas presented in randomized spatial configurations. Behaviour was recorded and analysed using high-resolution, frame-by-frame ethological coding, allowing the extraction of detailed temporal and categorical descriptors of arm movements, exploration strategies, decision sequences, and limb-specific involvement. We developed an experimental setup that allows us to identify the animals' strategies, preventing reliance on simple spatial memory and enforcing sensory-driven decision-making under conditions of uncertainty. This approach enabled the assessment of individual differences in problem-solving behaviour, highlighting intraspecific behavioural variation in O. vulgaris.