Please help ID this crab hitchhiker

[CruxOp]

i found this guy hitchhiking inside of a stylophora - i haven't been able to find any acro crabs that look like him and am stumped about whether he is good or bad. Can someone please help?

Huge thanks in advance

 

[Compliance]

literally 'inside' the coral?

So you snapped it and he was in there - or just inbetween the branches?

Either way - i don't recognize it specifically but it's TINY so it may be a case of a change of appearance as it gets older....

 

[cloak]

Gall crab?

 

[snorvich]

Blue eyes?

 

[CruxOp]

Wow - i think you nailed it. I researched gall crabs and found some info that points to him being bad. He was inside of a hollowed out section of the frag that looks exactly like the picture attached. That being said, it seems like they're considered a pest so I should get rid of him - correct?

 

[Fade2White12]

Based on the abdomen shape, I'd be inclined to think it was a Gall crab. They really will not damage corals. And I think they're pretty cool.

If you found the crab literally inside the coral, it is probably a female. They're pretty much limited to filter feeding and snacking on mucus and algae near the opening. Males are a lot more "free roaming" but have similar diets.

Personally, I'd put it back, assuming someone can give a definitive ID. Could you put it in a container in the water? It's a little hard to tell when it's out of water.

 

[CruxOp]

Hi Snorvich - eyes are not blue.

 

[CruxOp]

All - here is a pic of the crab in water. Please let me know what you think.

 

[CruxOp]

attachment

 

[CruxOp]

Super closeup

 

[FraggledRock]

baby emerald?

 

[CruxOp]

i think the shape is wrong to be an emerald, plus the way it was embedded in the coral didn't seem emerald-y

 

[Fade2White12]

Sorry for the late reply, but that's absolutely a gall crab.

I know some people (inaccurately) claim that they have killed certain corals, but that's just not true. It does the crab no good for the coral it lives in to perish. It's a pretty cool critter, IMO.

 

[CruxOp]

Thanks for the positive ID - I went back and forth before you responded and ended up putting her in the tank with the coral. She's a very well-behaved tank mate, just sits at the base of the coral all day. Fascinating little creature!