Mysteries of Octopus Blood

In contrast to humans who have iron-rich, red hemoglobin flowing in our veins, octopuses have blue, copper-rich blood called hemocyanin.

This natural, biological antifreeze, allows octopuses to survive and thrive in sub-zero temperatures where lower oxygen levels exist.

As both oxygen and copper form a stable complex at low temperatures, this gives the blood of octopuses this unusual blue colouration.

Nevertheless, there is a trade-off.

Hemocyanin is less efficient in oxygen transport than hemoglobin, making octopuses less suited for warm environments with high oxygen content.

So, the octopus utilizes an intelligent workaround.

They have three hearts — two for pumping blood to the gills and the remaining one for circulating it to the rest of the body.

When at rest or in danger, octopuses can stop their systemic heart to conserve energy..