Brown Emerald??

[rook]

Hello,
So a long time ago, maybe eight months, I purchased and emerald crab. Dark Green. After a month or so, I could no longer find him. I do have about 50lbs of liverock, so it was possible he was hiding, but for that long?
Then about a month ago I changed from cc to dsb, and in doing so, I removed everything from my tank, LR/corals/fish, and placed them in a 30 gallon tub for a few days. Then after the dsb was set up I placed everything back.
Last weekend, I purchased a hairy mushroom rock.
Last night I have found this crab crawling around
I have no Idea where it came from. It looks exactly like an emerald crab, claws/body/hairy legs/mouth, except it is brown.
Its claws are rather dark brown and its body is tan. Its legs and arms are sort of verigated(sp) brown and light tan.
So either this is a hitchhiker. Which is hard to beleave because the mushroom rock is not very big to hid him, and I inspected it quite well.
Or, this is my long lost emerald. But, could and emerald changed colors from green to brown/tan?????
I find it easier, still hard but easier to believe this is the emerald from before that was hiding in the rock somewhere.
Any thoughts? This is very mysterious.
Also if this is a different crab, and a different species of emerald, its it ok to be in my tank or should I find some way to remove it?
Thanks,

 

[krishj39]

While I suppose it may be possible that your emerald changed color, it seems that the color change is a bit too extreme for it to be the same crab. I keep finding new critters in my tank. Just yesterday I found a snail with a shell over 1 inch long that I had never seen before. So, I'd say it is more likely that the crab is a hitch-hiker. Emerald crabs DO come in different colors, I have one that is a rusty red color. A simple way to tell what a crab is SUPPOSED to eat is to look at the claws. If they have sharp points and look like they were designed to cut and shred then the crab probably eats meat and will probably cause you problems. However, if the crab eats algae, like the emerald, then the claws will have circular discs at the tips, designed to grab algae off of rocks. Basically, if the crab has discs instead of points on his claws, then he is probably reef safe. Of course, any crab may decide one day he wants to eat a fish or a coral. So, the SAFEST choice is not to have any crabs in your tank, in that they are always a gamble. But, I like crabs and have found them to be functional in the tank as well so I keep them, even with the risk of damage to other animals. HTH