Hitchhiker crab ID help needed.

[ScurvyDog]

Bought a Blasto at my LFS this afternoon and look what I found in the bag along for the ride. I've got him in a nano tank with a Bubble Coral and Xenia for observation. I've heard black claw markings mean not coral friendly I wonder how that translates to an all black crab with white leg tips and three white spots on his back. Anyone have any idea what it is, thanks in advance.

 

[graveyardworm]

Could a symbiotic crab that lives with something as a host. Hard to say. I'm not aware of an that live with Blastomussa in particular but its always possible.

Then again it could be a bad guy that finds enjoyment in tearing the flesh off your favorite coral.

 

[ScurvyDog]

Its seems to be nocturnal as I haven't seen it out and about during the day. I'm also not noticing any damage to the corals in the take with it, but I'll keep an eye out.

 

[dilbert_uk]

There are thousands of similar looking species of crabs with all different lifestyle and diet. Most are omnivore of course.

I got at least two tiny hairy crabs that don't seem to grow and are very shy and nocturnal. It took me actually half a year to find out that there are at least two.

Also at night, they usually stay in their holes in the live rock. About every month, I find a molt.

I don't know what they are living from and how much they eat. When I feed the corals or the only hermit in that tank, I occasionally give them one small piece of fish flake what they grab with both claws like a tablet. They disappear in their hole with it.

I never saw them damage anything, not the Caulastreas nor the hermit or other invertebrates.

As they won't grow huge overnight or eat all corals at once, I keep an eye on them, too.
If they would grow larger they wouldn't fit into the live rock anymore in this pico, and it would be easy to catch them simply by lifting the rocks. :lol: