what are these HITCHHICKERS IN MY ROCK!

[ElkhornSea]

Can anyone tell exactly what I have here. After 1.5 years of this reef up and running I just noticed two of these actually chilling out on a rock and breeding in my tank with the night-time LED's on. Looks like they have dug several holes out in my rocks. Should I never mind them, or get rid of them?? I have lots of soft corals and cleaner shrimp too, should I be worried? I couldnt find them on any crab identification sites.

[DustyReefer]

Kind of looks like an emerald crab but too red, I say remove immediately. He looks a bit hairy and angry and rule of thumb, hairy crabs are NOT reef safe. Especially if they're a hairy hitchhiker .

[91Atrac]

Does look evil. Ah


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[rssjsb]

Have you noticed any losses in the 1.5 years you've had them? Hairy and angry really aren't good indicators of anything, but almost any crab can cause problems.

I would probably leave them alone unless I started noticing problems in the tank. Even then, I would probably just move them to my refugium. But I tend to have more of a live-and-let live attitude toward hitchhikers than most.

[SushiGirl]

It does look a lot like an emerald. The body doesn't look hairy, just the legs, which emeralds have. Ours always turned white before they molted.

[DustyReefer]

It does look a lot like an emerald. The body doesn't look hairy, just the legs, which emeralds have. Ours always turned white before they molted.

It was my first impression that it looked like an emerald, can't tell by photo quality if it is just his legs that are hairy as well, so was just saying to er on the side of caution. Also I've seen red emerald crabs for sale in stores, which the particular crab in the picture does look to have a more reddish hue to it. As per these "red emeralds" Iv'e also heard they were not reef safe compared to the regulars, but never really looked into it, so who knows the validity to that.

As to just containing him to the sump that would probably be a good idea, that way he couldn't hurt anything and you wouldn't have to feel bad about killing the poor little guy.

[SushiGirl]

Red mithrax (emeralds), are no less reef safe than any other color "emeralds." We had 2 green and a large red & none of them were an issue.
http://farm6.staticflickr.com/5208/5380834155_31b9e72073_o.jpg

[DustyReefer]

Good to know for future references, emeralds are a very interesting addition if not just for some algae control.

[BANDIT ANGEL]

Despite some crabs feed on algae mostly, if they got a chance they'll always harass fish and corals. Remove crabs as soon as possible because I lost a lot of valuable ricordeas due to crab damage.

[ElkhornSea]

Thanks everyone. I didnt have a refugium to banish him into (I've built one and waiting for the return pump to arrive in the mail) so I did in fact end his friend's hairy life. To answer your questions, yes I have lost several of my soft corals, several mushrooms(eaten) since I have had the tank which I figure has been these guys. I hope I have eliminated the issue.

[SantaMonica]

I have one red and two big greens. Only see the green now; he eats some coralline, and an occasional polyp.