It looks really great when you back off and only see the octopus surrounded by black. It looks like its just floating in the abyss. Beautiful. I'm not sure about cyanea. They eyes look really large, but I am by no means an expert. I'm so jealous. I wish I lived in an area like that where I can go out and catch such beautiful animals so easily. I used to live in Japan, but that was only for a year. I would love to go back.
A couple of things you might record to try for an id:
Arm to mantle ratio
actual size (use mantle is the size of a ... rather than trying to come up with a number)
Have you ever seen an eyespot (ocellus) just under the eyes on the webbing?
You will want to get a red light for night viewing. If this is a nocturnal, the white light will deter viewing where we have found most nocturnals accept red (I leave mine on 24/7 when I have a nocturnal) and you can see but not photograph the animal in a comfortable lighting.
I have been watching for the false eye spots but he hasn't displayed any signs of it yet. I took the video this morning and he seemed very active. I'll see what he's up to when I get home and try to post more pics. He displays a lot of different patterns and textures. When at rest he is usually a tan color with a spiked texture. I am leaning more towards crescent than cyanea. I will be happy with either since very little seems to be known about the crescent and he very well may be the only specimen in captivity. However, if he is a crescent he is probably near full grown and may not have much time left. Does anyone here have any knowledge/experience with crescents?
Just did some research and found that the crescent octopus yet unpublished scientific name may be "Abdopus menepus". Been looking at a lot of o. Cyanea pics and comparing them to the few crescent octopus pics I can find and my pics of Julian. Still can't tell for sure. I noticed that the o. Cyanea often has pronounced white spots on thier tentacles along with false eye spots. Julian hasn't displayed any of these patterns, but I guess I haven't had him long enough to be sure. Also the crescent and cyanea octopus look so similar, they were only recently realized to be different species.
Thank you :). He must have been in an epic battle before I abducted him because his two forward arms are little stubs! They seem to be healing nicely though, as he already has two mini tentacles growing in and no open wounds.
Explaining to new keepers that missing arms were not likely a part of capture or human handling is often a topic. I have even posted a hunting video with all 8 arms (tentacles are used and look differently than arms in cephs and octos only have arms ) stuck in crevices in the LR entitled something like, "You can see why these guys come to us with arms missing".
I looked up Crescent Octopus in my handy dandy Cephalopods A World Guide by Mark Norman (he gives the official name as Octopus hawaiiensis but the names are dated with several having been changed since the book was published) and this is what he has to say about IDing it:
It is recognised by the solid build, broad head and distinct triangle of large white patches on the arm bases in front of the eyes. The common names comes from the pair of crescent-shaped white markings on the upper centre of the body.
Norman also mentions that it crepuscular (hunting early AM and at twighlight) and "will often have one or more arms running along the water surface". He should be interesting to watch and a floating food might show the odd arm behavior.
Do you think he is a crescent or no? I did capture him near the surface, in the evening. I mean really near the surface. He was at the edge of the reef at low tide on top of a rock. He was like two inches under the surface. He is definitely not the night tako (O. Ornatus). I've seen them. Not at all similar. He would have to be O. Cyanea or a Crescent right? Unless there is another species native to Hawaii that is even more undocumented. Thoughts?
It sounds like their hunting behavior for sure. There is another section I meant to quote that fits:
"This species occurs on rocky reefs from tide pools to at least 10 meters. Animals in intertidal pools work the very edge of the water and land ..."
One of the things to look for are rectangularish patches just below the head (where the eyes are, not the mantle) that appear to make a necklace around the top of the webbing. There are two photos in the book but one does not give even a good look at the crescent.