Temperature, pH and oxygen concentration are the three most important parameters that influence oxygen-binding capacities of the haemocyanin in cephalopod haemolymph. For survival at nearly -2°C, a cephalopod requires a highly specialised blood-gas exchange. In order to successfully compete with fish, which possess the more effective respiratory protein haemoglobin, cephalopods have developed a high level of haemocyanin adaptability. Despite their prominent position in Antarctic food webs and being highly abundant, very little is known about Antarctic octopod physiology in general and specifically of the role of haemocyanin as a mediator between the organism and an extreme environment.Applying an integrative physiological and molecular genetic approach, we studied the molecular structure of octopodid haemocyanins of polar, temperate and sub-tropical origin and investigated haemocyanin oxygen-binding parameters under different environmental conditions. We hereby aim to shed some light on the links between physiological adaptation and the phylogeny of octopodid haemocyanin during the adaptive radiation of these animals into Antarctic waters and to assist in explaining the recent biogeography of Antarctic octopods.DOI: 10.1016