Crab with white claw.

jtumbleweed · 11-28-2007, 01:03 AM

I seem to have a crab in my tank that has gotten big enough, or bold enough, to start eating hermit crabs. I have a 30 gallon reef that has been up for almost four months now. About a month ago I noticed a hermit body laying on the sand, and didn't know what to think since it had never happened before, and then nothing happened for a long time, so I just figured the hermit died while trying to find a new shell or something. Then, last week, I noticed another dead hermit body, just legs basically. As I was looking into my tank I noticed a white claw hanging out under the rocks. I could barely see into the crevice but I could see the face of a crab for sure. I can see into his little hideout just barley but I can't get a good look at it at all. I searched all over these forums, and on some sites other people have suggested, but I can't seem to find any info on the particular crab that I have. I know it needs to be removed, obviously, because it is killing hermits, but I would like to know what it is, and if I don't get it out soon, if it is capable of more damage, i.e. killing fish or hurting coral or other inverts. The crabs body looks to be about the size of a silver dollar, and it looks black, but it could be purple possibly. It is not hairy I don't think, and it seems to have one big white claw, that is very pointed and sharp. I don't know if it has one big claw and one small one, or two big claws, but I have only ever seen one big claw from the angle I can see into his crevice. I know without a picture its hard, but I was thinking that the one big white claw might be a tip off. Thanks --

Fly Guy · 11-28-2007, 02:05 AM

I bet your crabs arent really dying, but just molting.

have you done an actual head count??

Most likely your white legged crab IS still bad though.

jtumbleweed · 11-28-2007, 02:08 AM

Yeah, they are dead, the only thing left is red legs and eyes, the rest has been eaten. I know three are dead, and the other three that are left are huddling together in the front of the tank all day, which they never did before...

Twitterbait · 11-28-2007, 04:50 PM

can you get us a picture of the bad crab?

jtumbleweed · 11-28-2007, 09:55 PM

OK sorry guys, due to the fact that I can barely see the crab I mistakenly thought that it had one big white claw. I was moving some rock around today, and I must have disturbed it, because I saw it run from one side of the tank to the other and dive into its lair. When I saw it before it must have been sitting on its molt or right next to it. I am pretty sure I can ID it now if I go look really fast at some sites before I forget what it looked like. It is dark, like a dark green, or black, and it has white eyes. It looks like something I can easily ID, sorry if I wasted your time, but thanks for the input. I'll delete this post soon.

schmidt01 · 11-28-2007, 10:58 PM

Please don't delete the post. It would be helpful for us to see the crab and figure out what it is so that if some one else ends up with that same crab in their tank, they'll be able to use this thread as a resource to help them ID the crab. We all learn from eachother here!

Fly Guy · 11-29-2007, 02:58 AM

Quote:

Originally Posted by jtumbleweed

I am pretty sure I can ID it now if I go look really fast at some sites before I forget what it looked like. .

http://home2.pacific.net.ph/~sweetyu...itchcrabs.html

Loverotties · 11-29-2007, 07:02 AM

That's a good site Fly Guy!

jtumbleweed · 11-29-2007, 11:14 AM

Yeah, that is a good site fly guy, I looked at it yesterday, someone had posted it on another crab pest thread, probably you. Since I am having trouble remembering what it looked like from the fleeting glimpse I got of it, I think it looks a lot like the very first picture of the Xanthid crab, but I could be wrong. I tried the glass trap last night, but all I got was a rotting piece of shrimp I had to pull out before I went to work in the morning. Does anyone have a better way to trap a crab? For some reason I think that this one is smarter than your average crab, or maybe its just smarter than me.

--- I was going to delete this post because I got the description so hopelessly wrong the beginning, but like schmidt01 said, I guess we can all learn from this.

jtumbleweed · 11-29-2007, 11:30 AM

Has anyone ever used a retail crab trap?

http://cgi.ebay.com/X-Terminator-Man...QQcmdZViewItem

jtumbleweed · 11-29-2007, 06:34 PM

So I tore up the tank trying to get the crab out because i noticed it clipped one of the brittle stars arms, and I was adding some more rock anyway, so I went for it. Of course, and I figured this would happen, he was hiding in the last piece of rock I looked in. Here are some pictures of it as it sits now in a bowl in my kitchen awaiting its justified death in my friend mantis tank later tonight. I haven't ID'd it yet before I post this, so if anyone knows what it is it will save me a search.

Photo Sharing and Video Hosting at Photobucket

jtumbleweed · 11-30-2007, 01:35 AM

It looks to be an Atergatis Floridus. I don't think I could find a better match. http://www.flmnh.ufl.edu/reefs/guami...es/Image2.html

ChrisPrusha · 12-01-2007, 11:02 PM

Hermits don't huddle in fear of anything.

And hermits molts look exactly...exactly...like dead hermits.

The crab might be the problem, but I think it's far from a sure thing.

jtumbleweed · 12-08-2007, 11:55 PM

Susan the mantis shrimp had fun smashing the crab to bits. Got what he deserved. Since the crab has been out everything seems to be back to normal.