Good Crab? Bad Crab? Please I.D.

yossaria

yossaria

Member
Hi All,
I have isolated a hitchhiking crab. I am not sure what it is but suspect that it is a gorilla crab. Below is a picture. Its body and pincers are black or a very dark brown. It has white spots at the tip of the pincers and has white hairs on its legs. I suspect it is a bad crab because it seems to have been nipping at my bubble tip anemone. Apparently the BTA didn't like it because it moved to a different location in the tank! Thanks in advance for any help with and identification.
Cheers,
Yossaria
 
nick76

nick76

Active Member
Looks more like an emerald crab to me, I took a look at gorilla crab pictures and they appear to have their entire bodies covered with hair, not just the legs.
 
yossaria

yossaria

Member
I have two emerald crabs in the tank and they are both clearly green. This guy is pretty much black, but I do agree from the attached photo that it resembles an emerald crab. I have him in a beaker on my desk and am not sure what to do with him, but I am afraid that if I were to put him back in the tank, the anemone will be unhappy.
Thanks for the replies!
Yoss
 
saltn00b

saltn00b

Active Member
i have had emerald crabs that have been bleach white and even red. it looks exactly like one that just happens to be black. he even has the flat pincers for pulling algae. although it is still a safe bet to pop in your fuge, as "crabs will be crabs"
 
renogaw

renogaw

Active Member
emerald crabs are green versions of this crab. look up mythrax crabs, as long as the claws are cupped they are cousins.
 
R

rattler739

Guest
He does look a little black but that could just be the pic and as far as the color of it, i actually have a brown emerald crab. There are a few colors of mithrax crabs: to my knowledge they come in green, brown, dark brown or black and even a orange to pink. If in doubt put it in the fuge or another tank.
 
R

rattler739

Guest
oh yeah, if the claws are pointed get rid of it, if they are rounded then it should be ok.
 
R

rattler739

Guest
wow that is amazing color on that "emerald"
i wish i would have gotten one with that color instead of a brown one.
 
yossaria

yossaria

Member
Thanks all for the info. I took a look at the crabs pincers under a dissecting scope and they are indeed cup like. So, I suspect that this little fellow likes to dine on algae. Still, I am a bit concerned about how he interacts with my BTA. He is always hanging out on/in the live rock near or under the BTA and the BTA apparently is not fond of this. Has anyone every had a problem with emerald crabs (or their close relatives) harassing anemones?
Cheers,
Yoss
 
renogaw

renogaw

Active Member
i had one that lived under mine, and no problems. it may just be curious about the bta and will probably leave it alone with time. give it some shrimp or some algae and keep it full :)
 
puffer32

puffer32

Active Member
Its an emerald. Some times when they get big, they look like yours. You can tell by the claws its an algae eater, cup like you said. heres a pic of one of mine scrapping algae off the glass, he use to be small and green, but he has changed drastically.
 
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