[5] This octopus was described initially by the British zoologist John Edward Gray in 1849; the type specimen was collected off Australia and is at the Natural History Museum in London.

Its range extends from the Red Sea, the East African coast, and Madagascar, to southeastern Asia, Oceania, and as far as Hawaii.

[7] While most species of octopus are nocturnal, O. cyanea is diurnal,[4][10] although mostly crepuscular, being active at dawn and dusk.

Crabs may be killed by a bite and given an injection of toxic saliva, then chewed up in the beak of the octopus, while molluscs may have their shells drilled and the animal inside being predigested to ease extraction.

[15] However Octopus cyanea will socially tolerate other individuals by sharing tanks and dens and with typically no loss to cannibalism or escape.

They also exhibit significant levels of social repulsion, and individuals often chose a solitary den when given the option.