If the blood (called haemolymph in invertebrates) becomes deoxygenated – when the animal dies, for example – it loses its blue colour and turns clear instead. An octopus’s three hearts have slightly ...

While our blood is red because it consists of a protein called hemoglobin, octopus blood consists of ... They also have the special ability to colour and texture to blend in with their ...

Octopuses can change colour and pattern. When an aggressive male is about to attack another octopus, he will often turn dark, rise out of the seabed, and stretch his arms out in a way that ...