How Antarctic octopus survives in the cold

An Antarctic octopus that lives in ice-cold water uses a unique strategy to transport oxygen in its blood, revealed a research.

The study suggests that the octopus's specialised blood pigment could help to make it more resilient to climate change than Antarctic fish and other species of octopus.

"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."

This is important because it highlights a very different response compared to Antarctic fish, said lead author Michael Oellermann from the Alfred Wegener Institute in Germany.

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, but little is known about the adaptations employed by blue-blooded octopods to sustain oxygen supply in the cold.

"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," Oellermann added.

Octopods have three hearts and contractile veins that pump 'haemolymph', which is highly enriched with the blue oxygen transport protein haemocyanin (analogous to haemoglobin in vertebrates).

The Antarctic octopus Pareledone Charcoti has the highest concentration of haemocyanin in its blood - at least 40 percent more compared to other species, the researchers found.

The researchers say that these high blood pigment concentrations may be compensating for the haemocyanin's poor ability to release oxygen to tissues while in cold environments, and could help to ensure sufficient oxygen supply.

The study was published in the journal Frontiers in Zoology.