How a Cold-Blooded Antarctic Octopus Survives Frigid Temperatures

Octopopds are cold-blooded, so how can one survive the frigid temperatures found in the Antarctic? Scientists have taken a closer look at an Antarctic octopus that thrives in ice-cold water and have found that it uses a unique strategy to transport oxygen in its blood.

The Antarctic Ocean hosts rich and diverse fauna, despite the harsh and inhospitable temperatures that can be found there. The cold temperatures, which can be close to freezing, can make it hard to deliver oxygen to tissues due to low oxygen diffusion and increased blood viscosity. However, this also means that ice-cold waters contain large amounts of dissolved oxygen. This means that in Antarctic fish, this reduces the need for active oxygen transport by blood pigments.

"This is the  first study providing clear evidence that the octopods' blue blood pigment, haemocyanin, undergoes functional changes to improve the supply of oxygen to tissue at sub-zero temperatures," said Michael Oellermann, the lead author of the new study, in a news release. "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 haemocyanin at higher temperatures, this octopod may be physiologically better equipped than Antarctic fishes to cope with global warming."

This octopus has three hearts and contractile veins that pump "haemolymph," which is highly enriched with the blue oxygen transport protein haemocyanin. The researchers analyzed haemolymph from the Antarctic octopus and two species collected from warmer climates. In the end, the scientists found that the Antarctic octopus had the highest concentration of haemocyanin in its blood-about 40 percent more compared to the other species. These high blood pigment concentrations could be compensation for the haemocyanin's poor ability to release oxygen in tissues in cold environments.

The findings reveal how the blood pigment is able to support oxygen supply in both cold and warm environments. This, in turn, may explain why these animals range so widely across the globe.

The findings are published in the journal Frontiers in Zoology.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).