Oh ya, the Harlequin shrimp will eat your stars like there going out of style. I've watched them in the act in my tank so I'm 100% sure they do. I have an asteria problem as well and my two harlequins are doing a good job at reducing there #'s. Regardless though, eventually you will have to feed your Harlequins something or catch them and sell them to someone else but chances are your asteria problem will come back and probably in greater numbers too. Though it's not too hard to keep harlequins. I read that they can feed off a full sized star for weeks up to a month. Also you can buy a chocolate chip and keep it in your fuge. When the times comes ever couple weeks or so, cut off a leg and feed it to the Harlequins.
They really are the coolest little creatures and I wouldn't trade them for anything. Buy some, you'll love them.
Good luck
Sculp1n
