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Surprise! It's a Mimic!

Hi Dave,
I haven't seen the shell-chewing/dissolving thing you mentioned, sorry. I fed mine mostly live grass shrimp and the occasional hermit crab. They typically went for the grass shrimps immediately by enveloping them in the web. It's beautiful behavior - the whole body goes transparent and the mantle become extremely elongate and narrow, presumably to minimise the shadowing over the prey as the web comes over. As soon as the shrimp would tail-flip into the web the octopus would immediately flash its dark stripes. It was very cool to watch.
The other question you asked was about their vision - is this in relation to your animal's lack of interest in the confined crab? My impression is that their eyesight is comparable to any other species', but I also recall that most successful crab-in-jar trainings involve smearing the entire outer jar surface with fish or shrimp paste, which encourages exploration and often leads to incidental lid opening, and the animal learns the task by continued exploration driven by olfactory and not visual cues. I don't doubt the animal can see into the jar, but I suspect the correct combination of cues to prompt exploration are not there.
Hmmm... I will have to try this with a lid although I'm a bit averse to smearing it with anything that will pollute my already kind of dirty water.

On a side note, did you ever attempt to trigger mimicking behaviors by showing photos of different predators?
 
Your biofilter should be easily capable of handling some food smear if it's handling the octopus itself, I would guess.

I did not try to evoke any mimicking behavior, no. I'd be surprised to see much response to still images of predators.
 
Your biofilter should be easily capable of handling some food smear if it's handling the octopus itself, I would guess.

I did not try to evoke any mimicking behavior, no. I'd be surprised to see much response to still images of predators.
My octo tank is actually hooked up to a shark system so it's already a pretty high nutrient load tank. I can barely keep factors in check but they aren't horrible as I feed my sharks every other or every 3rd day only, they are just really messy. I see a phosphate spike a day or two after I feed but have a ton of GFO on the system to remedy this.

Ever try anything with a mirror in the tank?
 
So for the past 2 nights I have let her hunt what is in the tank. She has continued to eat snails at a snails pace (sorry, had to do it, it's now the bad pun that can't be unsaid) and I found a cerith and nassarius in addition to a couple more ninja star astreas in her "den" which I have not seen her in since her second day with me. Tonight I gave her some more crabs and decided to see just how hungry she was as the peppermint shrimp and a single emerald crab I gave her are still there but the crab in the plastic jar is finally, after a week or so, gone (I opened it up and left it in there).

I was a bit shocked to see the behavior I saw tonight as I've never seen this before in my years of octopus keeping. Typically when I have fed it essentially goes like this - put a few crustaceans in or offer a single piece of food and the octopus grabs it and then settles in to eat, ignoring whatever else is around it. Tonight was exactly the opposite with her - I dumped 4 fiddler crabs in at the same time and they landed near or on her. She proceeded to grab 3 of the 4 and wrestle with them, seemingly injecting toxins into them one at a time to subdue them and then ended up grabbing the 4th one about 10 minutes later. The video is not yet uploaded but I took a lot of photos after filming and they are.
 
Sorry, didn't realize that my phone started filming vertically instead of horizontally. I bet there's an app to turn the video 90° but I also bet that I don't know what it is. Anyone know of one that will turn it without degrading the quality? I wonder if I can even do that in Google itself.
 
I have had a number of peppermint shrimp do just fine in octo tanks BUT the oddity is, no matter how many I have put in, ONLY one survives and the others are eaten. I am not sure if they kill each other and then the octo eats them or one gets an assigned territory too close to the octopus.
 
I have had a number of peppermint shrimp do just fine in octo tanks BUT the oddity is, no matter how many I have put in, ONLY one survives and the others are eaten. I am not sure if they kill each other and then the octo eats them or one gets an assigned territory too close to the octopus.
The one in the video practically crawled across her. She has two in there that I added and they are actually looking quite pretty in there - they are turning really red and I know that at least one has eggs so we'll see if they do any better in a system without anything that eats them! :smile:

Seriously, though, it seems really odd to me that she shows no interest unless she recognizes them as cleaners, although I'm not sure that I've ever seen anything on octopuses visiting cleaning stations. She has eaten Nassarius, Astrea, Ninja Star Astrea, Trochus, Cerith, and Nerite snails now but still not a shrimp? Hermit crabs, fiddler crabs, emerald crabs, but again, puzzled by this lack of interest in shrimp. If this keeps up perhaps I'll add a coral banded shrimp to take care of some of the bristle worms. She grabbed 2 or 3 crabs again tonight despite not being all that hungry. She didn't really pay them much attention (she had 4-6 crabs last night as well as a snail) until one decided her arm looked like a nice meal or a pinching post. She then grabbed it, bit it, and then grabbed another one and held it until she was done killing off the first crab before taking care of it as well.

On a cool note, sorry, no photos yet, her arm that came in injured continues to grow and the arm that had the tip bitten off by the molly has begun to grow back.
 
I have taken to feeding her 4 crabs at a time and tonight was one of the cooler feedings as I saw her doing a behavior I had witnessed only sporadically and wasn't sure that it was an actual behavior or just from her touching the aquarium wall as she moved about. Anyway, she was "tenting" and standing up on her arms almost like an "octopod" (ha ha, play on tripod despite it actually being correct). I have seen this behavior before but tonight she was actively doing this across the rock and I saw her picking up shells so I take it as a hunting behavior. I wasn't able to capture this on video but when I fed her she "tented" again and when I fed her she stayed propped up against the glass. I was able video from a low angle as she moved one crab she grabbed into position to bite it and then moved the other into position to bite it as well before settling down for her meal. It only takes about 15 seconds or so to start immobilizing each crab but she definitely waited for a few minutes before starting to eat. I will post video when it is downloaded, again, about 15 minutes of video capture which is huge in size.
 
Tonight's feeding was a bit different than the normal ones as I decided to see how many crabs she could handle at once. Turns out she is limited by how many arms she can dedicate to each crab without getting pinched. Check it out. So many crabs, not enough arms...

Interestingly when she abandoned one of the immobilized crabs (aka dead) I examined it and did not find any evidence puncture or bite wounds. Looks like as she is enveloping the crab she is not injecting the toxins but perhaps spraying them. She did take the crab she dropped when I offered it to her afterwards so no wasted crabs tonight. 😁
 
No interest in peppermint shrimp still.

In this one she yet again shows that she has zero interest in eating a peppermint shrimp. They never touch her but they certainly go very near her and she shows zero reaction. I wonder if perhaps she recognizes them as a cleaner species? I would doubt it as I have never heard of octopuses visiting cleaning stations in the wild or in captivity but I suppose anything is possible.

By the way, she also much prefers fiddler crabs to emerald crabs as you can see from the video.
 
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