Crab ID - Black with marbled-white markings?

[gordonzo]

A large (1" dia.) crab came with my live rock. He is mostly black with marbly-white on his arms. He is very shy (can't get a picture - yet!) and stays in the porous rock. Occasionally comes out. He seems to pick stuff off the live rock and also responds to shrimp pellets placed near his 'lair'. He has 2 large claws which he sometimes uses to sweep water toward his mouth. I have only 2 fish (4 stripe damsels) and he seems to shy away from them - they will try to take the shrimp pellet out of his grasp! My tank is 3 weeks old - cycled with live sand/live rock. 55g, CPR Skimmer, Refugium, Ammonia-0, Nitrites-0, Nitrates-5, Alk-11, Ca-440, Temp-77F. Any idea of what he is?

 

[steve-s]

He has 2 large claws which he sometimes uses to sweep water toward his mouth.

Sounds like a species of porcelain crab by that description. Ther are many different color morphs for these guys.

Cheers
Steve

 

[cj10488]

Is this what you are describing except for different color???

James

 

[gordonzo]

My crab has a more oval shaped body. His legs are much thinner. His claws are very long and slender. I am still trying to get a picture but he is very shy. He will reach out of his crevice and take a shrimp pellet from my tongs but when he comes out, the slightest movement seems to scare him away.