Surprise! It's a Mimic!

[davelin315]

Also, besides crabs I have definitive proof that she is eating snails. This is a red banded trochus snail or rather the shell of one. There is nothing else in the tank or system that could chew holes through the shell like that other than her. This marks the second animal occupying a snail shell that I have proof of her eating, the first being either a hermit crab or cerith snail that she chewed through part of the shell to get to. The damage to this shell is far more obvious and is something completely new to me as I have never seen another octopus in my possession that has done this.

The shell is to the top right of her and a close-up of it is below.

 

[davelin315]

Last, a couple of shots from "below" while she is a bit spread out on the glass.

 

[DWhatley]

I've never had one bite through a shell either! Even when they opened live clams, the shells did not show holes.

 

[tonmo]

Cool! Years ago, D posted a link to a paper on cephalopod drill-holes:

Trends in Cephalopod Populations

A number of new studies citing climate change and fishing as making changes to the abundance and location of cephalopod populations are beginning show up in current publications. This thread is an attempt to collect the articles for review.

tonmo.com

 

[davelin315]

Recognizing cephalopod boreholes in shells and the northward spread of Octopus vulgaris Cuvier, 1797 (Cephalopoda, Octopodoidea)
Auke-Florian HIEMSTRA 2015 full article.

Very different pattern for the borehole, this one almost suggests a chemical weakening of the shell as it is rasped away along the spirals. Never heard of this happening before...

 

[sedna]

Super interesting- I’ve never had an octopus chew through a shell, either! Your kids can start a home jewelry business- shell jewelry with octopus drilled holes!

 

[DWhatley]

Very different pattern for the borehole, this one almost suggests a chemical weakening of the shell as it is rasped away along the spirals. Never heard of this happening before...

Thanks! I will read the PDF tonight and link it to one of our research topics. UPDATE -- looks like I found, read and posted this in 2015 so I won't repost but will reread.

I knew that octos were SUPPOSED to bore with their radula but have never seen it. I know there was a study that showed they (vulgaris as I recall) work on the muscle attachment first and only bored into the clams when the researchers altered the clams so that they could not use toxin to dissolve the hinge muscles.

I suggest that you not let this one bite you!

 

[davelin315]

I suggest that you not let this one bite you!

Lol, I will do my best! I would hate to have my bones dissolve at their thinnest portions so she can suck my marrow from the bone!

 

[davelin315]

So today she absolutely pounced on the crab that I added (a group of 4 fiddler crabs, one of which she immediately went after and flared her mantle out). I was not expecting this so did it film. She is also actively trying to bury herself as evidenced by this photo which confirms my suspicion that she has been digging to bury herself.

I also got some peppermint shrimp and will do on when I add one tonight to see her reaction.

 

[davelin315]

Gratuitous glamor shot.

 

[davelin315]

Tried the shrimp in a jar challenge tonight but I am pretty sure from the carnage in the tank that she is not hungry as of the moment. Not only ate the other 3 fiddler crabs but looks like she also ate 2 more that were in there and a couple of emerald crabs. There are exoskeletons and legs and claws everywhere.

 

[davelin315]

Well, she definitely does NOT like the crab in a jar yet. I opted for a crab that I could leave overnight without her pulling it out versus a shrimp which she might be able to pull right through the hole or might even escape on its own. I filmed for about 30 minutes but she didn't do anything until I dropped another crab near it which she pounced on. Will post that video when it uploads.

 

[DWhatley]

I hope this ravenous activity is not a sign that she is about to brood.

 

[davelin315]

Day 2 of the crab in a jar and she still ignores it. I wonder how much of this has to do with a potentially distorted view? Clear plastic in a uniform medium on the inside and outside should not refract light at all and should disappear from sight, which it does for me, but I wonder if the eyesight on the octopus is such that this affects their ability to see through a jar? I would think not but she hasn’t even made an attempt to touch the jar despite sitting only a couple of inches from her.

Will post a video of her lack of interaction over a couple of days now and also the odd sight of her not reacting to a shrimp that literally walks over her. She did take a crab when I was not filming that I dropped in and did so pretty aggressively and she clearly has good enough vision to sight these immediately. A that said, I am puzzled by why she doesn’t bother with the jar at all despite being hungry (even after consuming probably 4-5 crabs overnight).

 

[davelin315]

I hope this ravenous activity is not a sign that she is about to brood.

I don’t know enough about them to hazard a guess. In fact, the only accounts I have found about their eggs and offspring are that they are a smallish egg octopus (Jay Hemdal) with eggs being 3mm.

Still hoping that I can find more information on them!