What iv always wanted someone to do..even if it's very difficult would be to take a photo of their mouth. Iv never seen one yet in captivity with its mouth captured. But, of course it would be hard because their beaks are more internal than Squids and are surrounded by their arms and hidden inside a ring of skin. However...it would be hella awesome. I would like to see one one day if anyone manages to get a good shot.
At the aquarium though, the giant octopus they had their continousely kept sticking to the glass were its mouth was facing us the whole time. But, it's mouth wasn't visible so...people their had a big question mark on their faces and just assumed that their mantle cavity (gill) opening was their mouth...their breathing. It was hilarious cuz I remember a little kids show on TV that stated the same exact thing. But yea, only the suction cups were bared on the arms were they met...and the mouth was hidden as usual. Glad I explained it to them correcly though.