Midnight - A. aculeatus?


Blue Ring
Apr 11, 2016
new york
Hi this octopus which we called Midnight because he turns black like the background of the tank so much so you can hardly tell he is there. Anyway any input identifying would be appreciated. Thank you in advance


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More photos will be helpful, especially if it shows horns over the eyes or, is always smooth or shows small/large bumps over parts or all of the body or regular spots on the arms or under the eyes. How much information do you have on the area of origination? Knowing something about the area of capture also helps with "what we normally see" from an area. Can you give a good guess on mantle (the sack that contains the organs, often mistaken for the head) length and arm length or proportion to the mantle. Look at the tips of the suckers. Are they rimmed in purple or orange (they may not always show color, most will be a purpleish blue). Does it hunt late at night or do you often see it during the day?

It is a bit odd that it is so dark sitting on the sand. Generally, most will turn much lighter against a white surface.
Hi sorry, hard to get pics of midnight, she is from indonesia. Her mantle is about 1 1/2, tentacles about 5 -6 inches. There is webbing between them. No horns. Comes out alot. Sometimes with main lighting. Pretty active.


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The arm to mantle ratio and coloring highly suggest an octopus in the Abdopus genus. There are several that have been named and likely more that have not been fully studied. The two most common we see are a dwarf that is typically nocturnal and aculeatus, a diurnal species. At an inch and a half, it could be either and time will tell. If Midnight's arms grow to be about a foot in length, then very likely aculeatus. If it stays small and stops coming out in the light, then an adult of one of the others in the genus.

Often newly acclimated animals will be more active during the day than if they were in the ocean. Once it is well accustomed to the tank (about a month) its most natural hunting time should return. With some animals, we can alter this for a short period with a regular feeding schedule.
Hi i was able to get more pics seems like he grew. He is out with lights on most of time especially when he is hungry. I am having trouble feeding him with feeding stick because he grabs stick, drops the food and plays tug of war which ends with me letting go of stick and witing for him to let go LOL. Then he gets food. Anyway here are pics. Any input would be appreciated. Thanks
Steal the feeding stick is a common game, not at all sure why but we see it often. Usually, they will get tired of the new acquisition and it is easily retrieved but occasionally a treasure is captured over a long period of time. In one journal, the animal stole a turkey baster, disassembled it and kept the bulb for several days.

Have you named it? May I move the thread to the Cephalopod Journals forum in hopes you will continue recording your experience?
I'm pretty sure this is A. aculeatus and have changed the title for Midnight's journal to reflect name and expected species. Age, however, is not often an easy guess since the size range is quite diverse for all species. Observed growth would suggest a juvenile but they continue to grow (albeit more slowly) throughout their lives.
Hi it looks like Midnight built a den out of everything in tank. I dont know if she is male or female but i have seen her in a few days which usually means she might have laid eggs. If i am not mistaken but A. aculeatus are a small egg species. Is that correct? I cant see inside den to see. Thanks Tom
Sadly, yes, aculeatus (and most of the Abdopus genus) lay very small eggs. As far as I know, no one has ever raised any of this species to settlement.:frown:

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