After watching the similarities between your video and mine and verifying that the deceased was a female, I am definitely thinking that this was mating again. The fact that by the end of it he released from his position and didn't appear to inflict any further damage would seem to indicate that there was no outright territoriality or aggression going on, although there certainly was some aggression during the courtship itself.
That said, I do think that the interaction was simply too rough. The struggles when I first came down could have been going on for hours and in an already weakened state, could have easily resulted in the death of the female if she was resisting the overtures enough, which it appeared she was. I do believe that the arm was probably removed by the male and wasn't chewed off by the female. I did see them both out and looking very good previously without any signs of missing arms to the extent that I saw post-copulation. The forearm was certainly intact prior to this and my recollection of seeing an arm with a bit of regrowth on the 3rd to the right is probably correct. I surmise that he bit them off during their interactions but I am wondering where they are... the forearm is pretty darned big and to simply lose sight of it... I wonder if he ventured into her den and that's what started this whole thing.
I do believe that if I attempt to get another one while this male continues to live (hopefully with only one there he will start eating since I saw no signs that he was successful in transferring any spermatophores) I will look at how I can put them into separate tanks. I still continue to wonder if the lack of any eating is simply the aftermath of the stress they have already gone through prior to getting to my tank or if they were truly bothered by being in the same system as another octopus.
Well, the male passed away sometime last night and I believe that this could possibly be from the trauma surrounding attempting to deposit spermatophores in the female. It seems like the decline was fairly sharp after mating (or attempting to since I did not find any spermatophores in the female or anywhere else for that matter).
My conclusions after this latest round are that a temperature of between 60-62 degrees is probably ideal for this species.
They seemed to engage in mating activities at around this temperature and then both declined rapidly - the female expiring within less than 24 hours of mating and the male within about a week of mating. I cannot chalk this up to just the fact that they mated and the male died naturally thereafter but rather believe that the stress of attempted mating caused them to die when coupled with the fact that they were in such poor shape to begin with.
They do eat when the right conditions exist... I was successful in feeding the male a grass shrimp and a piece of table shrimp. Neither of these constituted normal healthy eating as I had to slowly offer and hold it and he essentially gummed the shrimp down over the course of about 20 minutes of slowly moving it towards his mouth, but he ate and that's an achievement.
My next trial will include separating a male and female and keeping the temperature around 60 degrees. If this is in fact the lower end of their acceptable temperature, then it won't be too stressful for them. I'll continue to offer foods until they eat and then, if all goes well, I'll introduce them to each other, but not until I witness aggressive eating.
By the way, the eggs lasted for two days and then they all disappeared. It's possible that the male went over and ate them, but I didn't witness this so can't say for sure. Not a single egg remained anywhere in the system, hence my suspicion that he may eaten the eggs.
Cassy's eggs started disappearing in the last two weeks and I was never sure who ate them. Do you have anything else in the system (serpent star, live crabs that did not get eaten)? Clean-up of most any eggs is often pretty fast.
Since the females have both had eggs it is quite likely that you are seeing very mature animals (since mature animals would be the largest, this makes sense for food import). Many articles will mention that the male dies shortly after mating and has a shorter lifespan than the female. This is NOT true of any of the two species I have had that mated (O. mercatoris and O. briareus) and @Neogonodactylus has mentioned a similar observation (with the blue rings and I think aculeatus) so it is unclear where the statement comes from but could be possible for species we don't observe in the states.
Size is not a particularly good indicator for age but it may be worth trying for the smallest active one next time. As much as this is frustrating, I wish I could be experimenting along with you
Oh, and only periwinkles that could reach the place where the eggs are. They were in a homemade nori clip in an area of good flow so possible that when the egg sac ripped open they scattered, but it the egg sac itself was pretty tough in terms of the membrane and too a razor blade to cut open when I dissected the first one.
Oddly, I don't think they rotted because I kept a batch of infertile vulgaris eggs in saltwater just to see how long it took. I will say that the water evaporated several times and the salt may have preserved them but I gave up on waiting after over a month.
Purchased 3 males today with the intention of separating them into different tanks linked into the main tank and then the bag floated under the return and instant acclimation... There is one that is very small compared to any I have gotten in the past, may pull that one if the opportunity presents itself and put it into a separate tank and then work on dividing the tank itself into two sides...
Unfortunately, no, the ghetto chiller set up is on to of the tank and when the bag drifted too close to the return it got caught in it and poured a bunch of water Into it. They are all still in hiding, which is a good sign I suppose, but I also cannot see them to judge their appearance and make conclusions on health.
By all appearances, the smaller one is the same species. Has the same overall look to it and the pattern of little yellow dots on the mantle is the same, just a much smaller mantle and shorter arms.
Any chance you know how many dozen fiddler crabs fit into a shipping container for Marine Bait Fish orders?