help identify this crab

D

duck

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Nov 30, 2003
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I have a couple of crabs that came with my oyster rock from the Georgia Coast. These crabs are both kinda small oe is considerably larger then the other but still only around a quarter or 50 cent peice. The crabs are black or really dark brown and seem to have a couple of red spots on there arms.. not many.

Also I seem to see a little hair on there arms but not on there actualy body. The crab body is the size of a dime but the second to front arms are twice as long as the rest of them.. The first set closest to there mouth are really small and they are constantly using them toe at or filter things. They have wierd blue eyes. They seems to just be filtering anf eating stuff off the rock staying in the same place not really moveing around or causing any problems.

any guess.. good or bad.... ???
 
Sorry I haven't been of much help in identifying your critters. FInding an online crab ID guide isn't easy.

Here's a porcelain crab. I don't think it's what you have, but it's what I found first.
pcrab_1697_2.jpg


Otherwise, some photos would be a big help. Is that possible?
 
I hate to say anything absolute, but the only crabs I know of with those appendages are porcelain crabs. Porcelain crabs have a good reputation for being reef safe, but there is a lot of conflicting and useless information out there. Porcelain crabs are also quite diverse, although we mostly seem to see the anemone crabs, and little guys like the one in the picture that come in on live rock.

In the end, all I have is my own experience. My guys have lived in a group for years. They are territorial with each other, but have not bothered anything else. They will use their appendages to grab anything from flake food to bristleworms our of the water column (yeah, I know, bristleworms aren't normally in the water column, but stuff happens). They will also comb surfaces (like my big sarcophyton) with their appendages. I hear claims that they only use their claws for territorial disputes, but have seen the crabs manipulate food with them.

In my opinion, the wavy appendages are the sign of a "good" crab. It seems like any creature carries some risk, and "reef safe" just means the risk is acceptable.

How's that for a long winded non-answer.

Duck,
You might poke around wetwebmedia to see if any of the crabs photos look familiar.
 
How's that for a long winded non-answer.
Click to expand...

I give it an 8.5. :D

I have at least 5 of those same porcelain crabs and love to watch them. I just now saw one pick up small bits of substrate with a claw and "hand" it to the waving arms- fascinating!
 
hmmm

well it definatly not that crab but it is kind of simular. I have two a big and a little one... The problem is they hang upside down at the very bottom of a porturding oyster shell at the bottom of the rock near the sand level.. I have tried to take photos but it is very dark and even using a flashlight to illuminate them they kinda blend into the rock. I have tried to catch them witha net but they outrun me and just go deeper into the rock... I will do my best to get one.. probly will be the smaller one but I would like to catch the bigger one as it will be easier to see with my cheap digital camera ..
 
picture

here is a picture I took.. it is VERY hard for me to take tank pictures... I hope these give you some kind of idea.

detail


This guy hangs upside and looks like he has small baseball gloves on his little hand and he waves them in the current and brings them to his face like he is collecting stuff from the water to eat. you have to get mega close to see this... this crab is about dime size body shape but his arms stick out so wide he is about an inch and a quarter across
 
Really sounds (and kind of looks, maybe) a lot like a porcelain crab. The rocks in the tropics and subtropics usually are full of those guys.

How many rear legs has it got. True crabs have 4 pairs behind the claws, porcelain crabs have 3 (plus a tiny pair for grooming in the rear).
 
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