Can anyone ID this little stinker

[weez1959]

Anyone know what sort of crab this is and is he good or bad?
He's in the sump right now waiting to hear from everyone. He's about the size of a dime.

[zhenya]

Louise,

Those are commensal crabs,often called "bandit" crabs due to their black mask-like stripe. I found them often in the Acropora colonies.

[FireEater]

It should do good in a colony if you place it right on top of one.

Here is a similar one I have. It has made a home inside my large Purple Porcillapora colony. I took this a few minutes ago. He has been in the same spot for about a year now.

[weez1959]

What does this little guy eat? not the corals I hope!
I found him in my acro also but I guess he was sharing it with my 2 yellow clown gobies cuz that's where they always are...

[FireEater]

They eat passing food particles and take care of their homes by eating any critters that might get on the coral.

[SouthBayPhoto]

Now he is going to eat your corals cuz he's ticked that you took him out of his home and put him into the sump!

[Ninong]

Anyone know what sort of crab this is and is he good or bad?
He's in the sump right now waiting to hear from everyone. He's about the size of a dime.

It's Tetralia nigrolineata (Family: Trapeziidae) and, as zhenya has already mentioned, it's a commensal crab usually found on Acropora corals. (P.S. -- The specific name nigrolineata means black lined in Latin. Nigro = black and lineata = lined, especially a geometric line or a boundary line.)

"Coral crabs influence the feeding patterns of crown-of-thorns starfish" by M. Pratchett, E. Vytopil and P. Parks from Coral Reefs, March 2000, Vol 19, #1, pg. 36.

Crabs of the genus Trapezia live in association with pocilloporid corals; Tetralia only in Acropora. "In feeding experiments where crabs were removed from all coral colonies we found that Acanthaster planci (crown-of-thorns starfish) consumed both Acropora nasuta and Pocillopora damicornis in equal numbers. When Tetralia and Trapezia crabs were present in their respective host species, A. planci consumed all the A. nasuta colonies but never consumed P. damicornis." The Trapezia crabs were more effective in their defense, breaking off thorns at the pedicle. The Tetralia crabs pinched at the starfish's tube feet, doing little damage.

You can read the full paper here.

Morgan Pratchett

[LAsps]

safe!

[Chasman]

I think after four years, they've figured it out.

[LAsps]

oh i did not realize this thread is that old.. I just clicked this link upon researching those Acro crabs on google