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You might PM mucktopus for an opinion as she has observed both in the wild. I'll offer a guess but I have no observation of fighting and no interaction observation in the wild so your thoughts are better than mine. I did noticed that at least one was male and that his hectocotylus was curled (starting at about 39 seconds and again at 53 seconds), not reaching as if to mate (as observed in other videos of different species and not always in situ) so I would guess territorial fighting. I watched and rewatched but could not see the third right arm on the second one to try to determine sex. You might rerun you full originals to see if you can tell from the full observation. That being suggested, I have seen as well as read of males attempting to mate with other males but in my observation (aquarium born dwarfs) the approached male was not yet sexually mature and the behavior of the approaching male changed once the other's sex was visually obvious.
Welcome to TONMO. Hopefully you will favor us with more in situ cephy video!
Thanks for sharing this- it's hard to know for sure.
The first octopus is definitely a male- you can tell by the way it carries its third arm, all curled up (visible at about 56 seconds). The other individual appears to be a female (no Hc groove that I can see). But male-female aggression can take place outside of a mating context, so it's hard to interpret the interaction. If the camera people had stayed back and the octopuses hadn't reacted to diver presence there's a good chance the interaction would have lasted long enough that we could evaluate it better. Either way, nice to see the video!
I have updated the original post with the finished, edited video, which also features an Octopus cyanea under attack from a damselfish. In the first scene, there was never really a consensus on whether they were courting or fighting, and the commentary reflects this.
Thanks Nick, always a pleasure to get a notice that you have added a video on YouTube. I still could not tell the sex of the octopus in the hole, and I think everyone notice that the aggressor was definitely male.
I need to mark the video for another thing too. We often have questions about keeping fish (often damsels) with octos and I don't often have something to reference to convince new keepers this is a bad idea.
So a producer licensed the footage in my video shown in the first post, along with a load of my other footage of Octopus cyanea, to make an episode of "Animal Fight Night/Animal Fight Club" for the NatGeo Wild channel.
I directed them to this thread, and told them of the doubt over whether the octopuses were courting or fighting. Beyond that I had no directorial input. I did suspect that they would sensationalize the encounter, as is the norm for these sort of shows, but I didn't think they'd go quite as far as constructing a whole fairytale out of the event. Someone has posted an unauthorized copy of the show on YouTube for us all to enjoy. What a load of nonsense!
LOL, not as bad as I expected but did make me grin. @mucktopus has seen and photographed cannibalism in O. cyanea but it was the case of a female deciding her mate made a good meal. How much octopus on octopus snacking goes on in different species is still much of a mystery. We do know of several species that live in close proximity and one newly described that appears to live in social groups.