Mariano, M.C., Louro, F., Pinto, P., Grave, J., Callais, V., Collazo, N., Pereira, B., Gouveia, D., Tavares, L., Almeida, L., Oliveira, R., Carmo, A.S., Sheppard, C.E., Marquês, T., Gentili, A., Barros, C., & Paula, J.R. (2026). The ocean as a laboratory for animal intelligence. Acta Ethologica, 29,(33).
Abstract
The ocean’s physical properties and ecological complexity shape a unique selective environment for the evolution of cog-nition and behaviour in marine life. This review explores how marine organisms sense, interpret, and act upon informationin a three-dimensional space that shifts constantly, influenced by light attenuation, sound transmission, and hydrodynamicflow. We combine information across taxa to show how social and environmental pressures have influenced both domain-specific specialisation and domain-general flexibility. From the diffuse nerve nets of cnidarians to the complex brains ofcephalopods and cetaceans, marine cognition displays multiple evolutionary pathways to abilities like problem-solving,learning, and innovation. In ectothermic fish, modular brain systems seem to manage specialised tasks such as social nego-tiation or spatial learning. Meanwhile, endothermic marine mammals exhibit domain-general intelligence characterisedby behavioural flexibility and cultural transmission. It is also discussed individual and social learning behaviours, includ-ing cooperation, imitation and teaching, and their ecological significance in marine ecosystems. Unknown insights intocognition under natural conditions are now possible thanks to recent technological developments, including biologging,autonomous vehicles, acoustic monitoring, and neurogenomic tools. Finally, we discuss how anthropogenic stressors suchas pollution, artificial noise and light disrupt behavioural plasticity, with implications for adaptation and species resilience.This review combines evolutionary, behavioural, and technical perspectives to present the ocean as a testing ground forcognitive evolution. Furthermore, we also advocate for the broader inclusion of marine ecosystems in ethological andcomparative cognitive studies.
Keywords
Marine cognition; Cognitive evolution; Anthropogenic impacts; Behavioural flexibility
