David Fleetham / Day / Big blue octopus (Octopus cyanea) with diver in background. Hawaii. September 2012.

Alex Mustard / Reef octopus (Octopus cyanea) portrait near wreck. Gubal Island, Egypt. Red Sea.

Georgette Douwma / Common reef / Day octopus hunting for crustaceans and fish, enclosing coral head with arms and webs, using the arm tips to flush out prey into waiting suckers {Octopus cyaneus} Andaman Sea, Thailand

Georgette Douwma / Common reef / Day octopus {Octopus cyaneus} at rest on coral reef Sipadan, Malaysia

David Hall / Day octopus (Octopus cyanea) jetting over coral reef. Komodo, Indonesia.

Magnus Lundgren / Wild Wonders of China / Big blue octopus (Octopus cyanea) , Xiaoliuqiu Island, Taiwan

Magnus Lundgren / Wild Wonders of China / Big blue octopus (Octopus cyanea) close up of eye Xiaoliuqiu Island, Taiwan

Gary Bell/ Oceanwide / Reef Octopus (Octopus cyanea) pair, Milne bay, Papua New Guinea

Gary Bell/ Oceanwide / Reef Octopus (Octopus cyanea), Milne Bay, Papua New Guinea

Shane Gross / Day octopus (Octopus cyanea) hunting along a pristine coral reef off Alor, Indonesia.

David Fleetham / Divers looking at Day octopus (Octopus cyanea). Hawaii. October 2017. Model released.

David Fleetham / Day octopus (Octopus cyanea) jetting in mid-water over a sand bottom, Hawaii.