Houdini: O.mercatoris - Itty bitty little fella

bagarius

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I got a new octopus today. I drove eight hours round trip to pick it up. It was being marketed as a merc, but the shop guy was fairly honest in that he wasn't sure if it was a merc or a baby of something else. It's not afraid of me; its a brave little guy. It's mantle is about 3/8ths of an inch long, and it's arms are about two inches long at best. The best part is that as far as I can tell, it has all eight arms. It may not be afraid of me, but at the same time it's not very social. It will sit there and look at me and fairly ignore me.

I acclimatized it for two hours with the turkey baster method.

I've also attached some pics. Hopefully you guys can help me ID this bugger!
 

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DWhatley

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I see nothing that would suggest something other than a merc (big eyes, three star like points on the eye, mantle to arm ratio all fit). Once it settles in you will have a better idea. I highly recommend finding a cluster of the large purple barnacles with multiple sized shells. All my mercs have taken these as dens (not always permenant for the males) at some point in their lives, the females have moved to them and not left (but will occassionally switch overnight for what I suspect is an invitation for the clean up crew to clean house as they return the next day). Once situated there is a classic merc pose that is hard to miss if you have a good view. You will see one arm (sometimes two) centered between the eyes and rolled back over the mantle. I have seen others do this once in awhile but mercs take this pose most of their awake den time.
 

bagarius

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Thanks! Will it get much bigger? I'll check the fish stores and see if there's any live rock with barnacles on it. One of my pieces of live rock does have some sort of bivalve stuck to it though lol. One final thing, should I take measures to keep this little guy separate from a roughly four inch Atlantic anemone and a coral banded shrimp that I have? My old aculeatus had no problems with them and (amazingly didn't eat the shrimp),but the aculeatus was a heck of a lot bigger; I'm worried this little guy could get hurt, killed or eaten.

Thanks!
 

DWhatley

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Wrong kind of barnacle. The barnacles I am referring to are not native for the mercs but they like them anyway. They can be found on eBay , many fish stores and in most novelty stores near the shore (in spite of the fact that they are not native to that beach area).

I would worry about the anemone but not the shrimp (even though they can be quite agressive about wanting to clean unwilling partrons - Harvey rules my 140 :smile: and scares the trigger half the time). I have seen my flower anemone start to digest my antler that just stumbled across its path (I was able to rescue the antler and moved it to another tank).

My tank born and tank bred mercs all ended up with mantles between an inch and an inch and a half. The wild caught mother/grandmother was much larger (maybe 2") so like many we see the size can vary considerably but I think you definitely have a baby at 3/8" (I suspect you are under guessing the length though or you have a good macro lens).
 

bagarius

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I do have a pretty good macro lens. As you can see, his mantle is a bit smaller than my index finger fingernail. The tupperware tub it's in is right against the outside glass of the tank so you can see it's size well. I see what you mean about the barnacles. That'll be much easier to get ahold of methinks. Good stuff. I just got the anemone from an LFS that I have an incredibly good rapport with, hopefully they'll be willing to take it back.

Thanks D! As I lurk, your posts are always useful reading. :smile:
 

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DWhatley

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My bad, with the finger comparison, you win the size argument hands down. It is very rare to find a WC merc that small.

I have often said that mercs will not take regular frozen shrimp but Sleazy has made a liar out of me and seems to really enjoy it. One trick, I think, is to cut a piece that is about the size of a shore shrimp in both length and thickness. I have also been very successful with freshly killed shore shrimp from a pipette and, as odd as it may seem, Cyclop-eeze. If you have not seen Gholand's Vary's or My Trapper threads, had a look at them and the photos of the young mercs we were able to bring to adulthood. Greg has the best photos but I compete well on volume. If you have trouble locating them, let me know and I will go link hunting.

Try to be sure the barnacles have not been coated. Fortunately, most (in not all) of this kind are not. I recomend placing the cluster about midway in the water column and surrounding it with LR. It took Sleazy about a week to move in but I can see her even in the daytime now. Trapper and Miss Broody also stayed visible the rest of their lives after they took the barnacles. My males would move in and out of them but in often enough to make them high on my recommendation list for enjoying a merc.

If you have not done so, I also recommend setting up a red light and leaving it on 24/7. Mercs seem particularly well adapted to accept even relatively bright red lighting if it never goes completely dark (no so with my experiences with briareus).

Glad my octo ramblings are helpful.
 

bagarius

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Update!

Before I went to bed last night, I put a hermit in the enclosure with this little guy. When I came out this morning, all I had was an empty shell!
 

bagarius

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Update!

I actually fed this guy today, and it vigorously and aggressively killed and ate an entire ghost shrimp. It's eating really good, and is quite curious. I'm leaning towards it's being a female, but I have no way to know for sure yet.


edit- it just ate another ghost shrimp. Voracious little thing!

also, added some pics...
 

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