Crab ID please

alshayazoo · Aug 10, 2016

This little guy came in on some live rock. Any ideas what kind of crab he is and if he is beneficial?

Salty1962 · Aug 10, 2016

Mithrax Crab, Mithraculus sculptus . Algae and debris eater, sometimes even bubble algae. Try to keep him fed, they are crabs and are opportunistic feeders. I had one clear out my gobies one time.

neuwave · Aug 10, 2016

It could be from the family of Mithraculus crabs but it isn't the normal Emerald crab or red emerald that is known for eating bubble algae. Looking at the shape of the joints "elbow" the crab is lacking the round bulge on its exoskeleton. It seems to look like a crab from the Xanthidae family of crabs.
Is this Florida/Atlantic rock or Pacific Ocean rock? Looking at your profile it says Kawait so I assume that it's rock from the Pacific. If so that would eliminate the Emerald crab (Mithraculus sculptus) since it comes from the tropical western Atlantic.

alshayazoo · Aug 11, 2016

neuwave said:
It could be from the family of Mithraculus crabs but it isn't the normal Emerald crab or red emerald that is known for eating bubble algae. Looking at the shape of the joints "elbow" the crab is lacking the round bulge on its exoskeleton. It seems to look like a crab from the Xanthidae family of crabs.
Is this Florida/Atlantic rock or Pacific Ocean rock? Looking at your profile it says Kawait so I assume that it's rock from the Pacific. If so that would eliminate the Emerald crab (Mithraculus sculptus) since it comes from the tropical western Atlantic.

Thanks for the feedback. Being in Kuwait, everything is imported from all over the world so no telling where the rock could have come from. The LFS said they had had this rock in their tank for 2 or 3 years.

I looked at pictures of both Mithraculus and Xanthidae and it seems that this one resembles a Mithraculous more in overall body and claw shape. It's body isn't as squat as the Xanthidae pics that I have seen.

Thanks again for the help!