Crab ID please

[tkrause9899]

http://img217.imageshack.us/img217/1884/img0176kt6.jpg http://img217.imageshack.us/img217/5233/img0181ur9.jpg

I was wondering if you guys could tell me what kind of crab this is. I found him hidden in a rock and just recently was able to get him out.

[tkrause9899]

Any ideas?

[crpeck]

Your picture doesn't give a close enough shot to ID it. The claws are the key. The worst predator crabs have the very sharp tipped claws where the primarily algae eaters have rounder tips.

This crab is small enough that he may not have developed the claws he will have when more fully grown. Right now he looks pretty harmless, but if he's the crab I think they get REALLY large. Is that Florida rock he came out of?

Here is the wetweb media pages with a lot of info on crabs.

http://www.wetwebmedia.com/swcrabidfaqs.htm

[tkrause9899]

Do you happen to have any examples of the different types of claws?

[Whys]

Ahh yes... the fabled Blurry Crab. Some say it's just a hokes, as no one has ever produced a clear photo.

Sorry, no idea, just bored. :]

Probably best you got him out tho. Those claws look sharp and pointed. He still moving, or did he give his life to science?

[crpeck]

Okay ... here is one guy I trapped out of my tank. Note that the claws are blunt and similar sized. This guy is more likely a scavenger/algae eater. But I trapped him out anyway because safest rule of thumb is that no hitch hiker crab is a good crab. many of the crabs not sold in the hobby get too big and they're all oportunists.
<table style="width:auto;"><tr><td><a href="http://picasaweb.google.com/lh/photo/RiFntjUvRQM_8gcHEbgvMw?authkey=Re9c9DNemtA&feat=embedwebsite"><img src="http://lh6.ggpht.com/_2NsBbDJyUzs/SXwOwZAIw_I/AAAAAAAAC6U/Za2RiIeqWjM/s800/DSC00232.JPG" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="http://picasaweb.google.com/cathyrpeck/Fishpics?authkey=Re9c9DNemtA&feat=embedwebsite">Fishpics</a></td></tr></table>


As a contrast, do an image search for "gorilla crab" and check out the claws. One is bigger and they're very sharp. That's a clue that it's a predator crab.

[crpeck]

Not the best picture, but check out this guy's claws ... and he is a small specimen. See how much sharper they are?

http://www.tbsaltwater.com/thepackage/images/gorillacrab.jpg

[crpeck]

If you read through the wetweb media pages on the link I posted and do some Google searches you can find a lot of good info. There are so many species of crab it's tough to get a sure ID.

But in general, seek out pictures of Xanthid crabs. If your little hitch hiker looks anything like those, then he will be a fish killer when he grows up.

That said, I had a Xanthid in my tank for over 3 years that I just couldn't trap. They're very crafty. I made a point of feeding him and finally managed to catch him before he killed anything.

But another, who managed to stay undetected grew large enough that I found out he was there when I started to have fish disappear. It's the rock and sand sleepers they get first, like wrasses and sand gobies. He's the one who I'm trying to find the picture for you .... I was really happy to get him trapped out.

[Whys]

<a href=showthread.php?s=&postid=14235516#post14235516 target=_blank>Originally posted</a> by crpeck
<img src="http://lh6.ggpht.com/_2NsBbDJyUzs/SXwOwZAIw_I/AAAAAAAAC6U/Za2RiIeqWjM/s800/DSC00232.JPG" />

Neat... you found a red emerald. Seriously, nearly everything about that crab is identical to an emerald.

[crpeck]

Yes ... he is a type of Mithrax crab as Emeralds are, too.

Only difference is that his type gets much larger. I probably could have left him in for quite a while before he started making trouble and he might have been a good scavenger.

[tkrause9899]

Thanks for the info. I'd try and get a better picture but I spilled saltwater all over my camera and ruined it so I'm stuck my iPhone. The claws definitely aren't as rounded as those of the mithrax but they also aren't black like the gorilla crabs.

[crpeck]

Ooh ... sorry about the camera.

This crab is really small and it is going to be hard to ID him. They can look really different between the juvenile and adult stage.

Really, the chances of him turning into a gorilla or stone crab as he grows up are really strong. For as little as an emerald or other reef safe crab costs, you're really best off to not take a chance on your hitchhiker.

Do you have a sump or anything you can throw him in while you decide?

If you want to try and get a better picture, it would be fun to have a look and see if we can match him up.

[returnofsid]

Emerald Crabs are Green Mithrax. Mithrax also come in red. I've yet to see them purple with yellow pokeadots or rainbow patterned....but I'm still searching.