acro crabs
 

Can anyone tell me the benifit of an acro crab?
What purpose do they serve hosting on an acro the only thing I see them do is sit there move abit and make the polyps on my acro close where they are sitting so if anyone knows the purpose of these guys pls advise tia.

I believe this might help: http://members.aol.com/iq3d2/articles/trapezius.htm

Drew thanks for the info it was very helpfull. So the hosting crabs eat mucus and tissue aswell as probe the polyps as to make the coral colony tougher a happier thus grow faster intresting0X:

You're welcome :)

Generally speaking, it seems as though the crab is provided protection and a food source. In turn, the crab offers protection to the coral.

I believe some people on RC are trying to determine if they eat red buds. They want to use them to control the population of them in there tanks as a preventive measure.