An Antarctic octopus that lives in ice-cold water uses an unique strategy to transport oxygen in its blood, according to research published in Frontiers in Zoology. The study suggests that the octopus's specialized blood pigments could help to make it more resilient to climate change than Antarctic fish and other species of octopus. The Antarctic Ocean hosts rich and diverse fauna despite inhospitable temperatures close to freezing. While it can be hard to deliver oxygen to tissues in the cold due to lower oxygen diffusion and increased blood viscosity, ice-cold waters already contain large amounts of dissolved oxygen. In Antarctic fish, this reduces the need for active oxygen transport by blood pigments (e.g., haemoglobin), but little is known about the adaptations employed by blue-blooded octopods to sustain oxygen supply in the cold. Lead author Dr. Michael Oellermann from the Alfred-Wegener-Institute, in Germany, said: "This is the first study providing clear evidence that the octopods' blue blood pigment, hemocyanin, undergoes functional changes to improve the supply of oxygen to tissue at sub-zero temperatures. This is important because it highlights a very different response compared to Antarctic fish to the cold conditions in the Southern Ocean. The results also imply that due to improved oxygen supply by hemocyanin at higher temperatures, this octopod may be physiologically better equipped than Antarctic fishes to cope with global warming." Octopods have three hearts and contractile veins that pump “hemolymph,” which is highly enriched with the blue oxygen transport protein hemocyanin (analogous to hemoglobin in vertebrates).
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