What kind of “crab?” is this?

[Cdav929]

Have had my evo 13.5 set up for about 1.5 months now. Bought some aquacultured live rock from Florida which has been great so far- however today I just caught this fella and was wondering if anyone knows what it is? 
I know there’s at least one more of them in there but haven’t caught him yet. 
 

[Jungle_vip]

Looks like a specie of decorator crab to me

[Tired]

Ooh, neat find! I agree- decorator crab. It looks odd because it's covered in camouflage materials. 

 

Decorator crabs are a bit iffy in a reef. Some species can get relatively large, and at that size, may snip and wear corals or may be a threat to small shrimp. However, some species stay pretty small. I have a micro decorator crab (carapace about dime-sized) that I don't expect to get much bigger, and it's a model citizen. 

 

I would say you should either keep it, or give it away. If you keep it, all you have to do is keep half an eye on it in case it gets large. If it starts getting big, just rehome it. If it stays small, no problem, you've got a cool crab now. Decorator crabs stay out in the open, since they're well-camouflaged, so it won't be too hard to remove if it does start getting a bit big. Especially not in a smaller tank. If you don't want it, don't kill it, I'm sure you can find someone to take it off your hands.

[Cdav929]

That’s be super cool if it ends up being a decorator crab of some sort. I was just a little worried it was maybe a juvenile gorilla. 

[Tired]

It looks pointier about the head than a gorilla, and has smaller claws. The fuzz on its legs isn't actually its fuzz, I'd wager- that's something it's wearing. 

 

This is the kind of micro decorator crab I have. I don't know if yours is the exact same species, but you can see the shape of them is the same. 

[Jungle_vip]

+1 on rehoming vs death. Plenty of people would go out of their way to scoop him up if you didn’t/couldn’t keep him. 
 

Gorilla crabs are more stout than that guy. Their claws are thick and body more oval.  More like a typical crab shape thats seen. Have the appearance of strength. Usually black claw tips and coming to a point. I had one hitchhike into my tank when i was 19 ish. Ate my first flame angel. Acclimated it. Watched swim for 20 mins. Got ready for work. One quick check an hour later........ damn crab was munching away and flame was dead. RIP gorilla crab. Eye for an eye. JK but not really. If I knew then what I know now I would have saved to give away. 

[king aiptasia]

On 1/31/2021 at 9:14 PM, Tired said:

It looks pointier about the head than a gorilla, and has smaller claws. The fuzz on its legs isn't actually its fuzz, I'd wager- that's something it's wearing. 

 

This is the kind of micro decorator crab I have. I don't know if yours is the exact same species, but you can see the shape of them is the same. 

decorators have hairs that help them attach things to their body

[Tired]

They do, but the hairs aren't usually as long as are in OP's picture. It looks like that crab has found some detritus to wear, and possibly small pebble bits. I'm curious how much of the pebbled texture is shell texture vs pattern vs actual pebbles. Would love to see this crab a bit larger. 

[Cdav929]

And the hitchhikers keep coming. Found this molt today. Def different from the little guy I posted about above. He has the black claws though that worries me a little 

[Jungle_vip]

That’s a meat eater. No bueno for me

[Tired]

Yeah, that one's not good for a reef. Neat in a 'fuge, though. Looks pretty small, so you have awhile before it gets to be a problem. Try bottle traps.