I've rigged feeding sticks in the past. Take a wooden dowel, drill a tiny hole in one end of it and use the end of a smallish plastic zip tie as a "spear". Use crazy glue to fix it in place. The zip tie is tough enough to pierce shrimp, clam, and other meaty foods but not a) metalic, or b) sharp and dangerous enough to hurt anything in the tank.
You could also use the commercial, off the shelf, fish tank grippers etc. to do this, if you want to spend some money. I am the king of stingy and
DIY 
You are BEST to target feed these monsters of the genus Ophiarachna and not let them just "scavenge". IF hungry, these bad boys WILL trap and eat your fish. I have PERSONALLY witnessed this when my green brittle took down a yellow watchman goby in my 75G.
They set up in a "stance" where their body is lifted from the sand bed and they are supported in the form of an inverted "basket" by way of their powerful legs. They will stay like this until an unsuspecting fish travels beneath it. At that point, they POUNCE down on the fish and trap them.
They can get rather large as well. I had a brown brittle star that was more than 1 foot across before I gave him away.
Dave
