Crab Id -- Please Help

[sothoth]

Any ideas on this crab species? I know the image quality stinks but the little bugger is very shy.

It's a very clever and industrious crab. It appeared as a stow-away a few months ago and has gotten much bigger since I first saw it. At first it dug tunnels through the live sand, under the live rock. It would only show itself if it was very quiet but if I so much as twitched it would hide. It's recently relocated its house to a hole in a rock. The hole had a front and back door. The crap dragged an empty clam shell from one side of the tank to the other so it could stuff the back door of its hole with the clam shell. It found a snail shell and further blocked the back door of the hole.

As much as I like it, I'm paranoid that it's predatory. I've never seen it eat, so I don't know if he be carnivorous or herbivorous. I've had zoa's disappear FAST and I'm quite sure I have a zoa predator in there. Could this be it? I've suspected zoa spiders and zoa nudibranchs but since I've never seen a spider or slug, I must be open to the possibility that it's been this clever critter.

You may be tempted to guess this is a porcelain crab, but it's really not. This crab has a much more compact body and claw compared to the porcelain crab which has a small body size relative to the claw size, and the arms/legs of the porcelain crab are much lankier than this fellow. This one has pretty stubby legs and a stubby claw. In addition, this crab is has larger spots than the porcelain crab, who has smaller spots and more of them. The only ID I can make of this crab is that it's a "possibly-soon-to-be-killed-for-eating-100s-of-beautiful-zoanthids-over-the-last-month-or-two crab." That's just the common name, I don't know the latin version of the name.

But I would hate to rid myself of a cool looking crab, esp if he's being falsely accused of eating zoanthids.

I could also just plop him in my refugium, provided he's not going to be a menace in there.

Again, sorry these images stink so bad. Any suggestions are greatly appreciated. I'll try to snap a better photo or two and post more if/when I can get any. I've been trying for a while to just get these so I'm not too optimistic of getting a better picture.

 

[Mr Miagi]

I could also just plop him in my refugium, provided he's not going to be a menace in there.

Its probably a little harsh, but assume any crab is a harmful crab until you've gotten a good ID. And that in itself is a very hard thing to get. As you could imagine, there isn't a tremendous amount of literature dedicated to the identification of crabs. If you refugium is for macro-algae, just whack it in there. Im pro-crab life, so I support anyone willing to save there crab from the Porcelain train. He might serve a useful purpose in the scheme of things. If he hasn't eaten copious amounts of the Macro algae visible in your display id say he'd be fine in the Fuge.

 

[sothoth]

Any guesses on whether this guy could POSSIBLY be a zoa eater??

Alas, I guess I need to take the attitude that he needs to go into the 'fuge as soon as I can net him out of the main tank. I've never seen him eat anything however he occasionally seems excited when I put brine or mysis in the tank so I assume he's an omnivore or a carnivore. Either that, or he thinks frozen shrimp smell as bad as I think they smell and the excitement is really a protest.

I had 5 rocks with at least 45-50 zoas on each rock. One rock at a time, all zoa's have been decimated. They're there one day, ALL GONE the next. If this is him, I'd say a transfer to the 'fuge (exile) is being really generous, given the loss of over $200 of zoas over a month.

Thanks for the feedback.

 

[wflash3]

I recently had to take a hermit out my tank too. He was knocking over rocks and even killed my turbo snail for his shell And when one of my fishes was almost dead, but still alive, he grabed him and finished the job! If u think this hermit is doing anything wrong you should take him out fast!

good luck

 

[sothoth]

Very interesting.

I've never seen one of the hermits wreaking that level of havoc, but that's something I'll keep my eye on. I looked closer at my crab's lair and noticed he's making use of a nassarius snail shell now, but I don't know if he killed the snail or what. I think it's time for a relocation. This will be great fun trying to get him out of my tank.

This morning (monday) one of my cool ricordia rocks was knocked off it's regular spot and the ricordia were dead. It must have been like that most of the weekend. Very sad. I suspect the crab still, but obviously I can't prove his guilt so I'll transfer him to the 'fuge as soon as I can get him in a net.

 

[sianeds]

Oh good luck I don't envy you that task

 

[sothoth]

Got a couple of good images today. Well, one is quite nice, the others slightly blurry, but I won't complain, you can get a better sense of what he looks like with these pics. I also got a picture of my fanworm with a wrasse swimming by and added that just because I like 6-line wrasses.

I'm still naively holding out hope that one of you knows what kind of crab this is, and that it's the bugger that's been eating my zoas.

On another note, I must say that this crab isn't real attractive when you get a close look at it's face. I think only its mother could love it. Haha.

 

[wflash3]

nice wrasse =]

im waiting for my LFS to get some in so i can get one myself! how is yours doing in your tank? sorry for changing the subject by the way

 

[sothoth]

nice wrasse =]
im waiting for my LFS to get some in so i can get one myself! how is yours doing in your tank?

The wrasse is a very cool addition to my tank. It's a very happy-go-lucky fish. It swims all the time, checks out every nook and cranny of the tank. It seems like a very busy beaver. It's always hungry. It's very curious about anything new I put in there.

I've heard they can become nasty with really peaceful fish but I see no signs on that with mine. He's been in there for almost a year.

 

[Mr Miagi]

If you have a sump why not remove him to their, and see if a smaller colonies of Zoanthid thrive? If they dont, you know he isnt the issue, and he can go back in. It beats waiting for an ID which may never come. Try some basic Google searches for Zoanthid predators?

 

[sothoth]

If you have a sump why not remove him to their, and see if a smaller colonies of Zoanthid thrive? If they dont, you know he isnt the issue, and he can go back in. It beats waiting for an ID which may never come. Try some basic Google searches for Zoanthid predators?

Yeah, I'll move him, I know you're right about that. It's just going to take some time to get him out of there without tearing apart the tank. Today I experimented with suction to get him out of his hole.