Sign of feather duster feeding?

A few days ago I bought a nice looking red and white featherduster. It is semi-see through I suppose, anyways I noticed right away when I began the acclimation when I added tank water to the water it was in it started gaining what looks like green lines and then the green color went from the tips down to the center. I was concerned then thought that it may have been catching food. It consistantly does it now when it is open and I have it in a spot with good current. I would think that the lines are the parts of the feather catching food and then the green moving towards the center is the food moving to the mouth. What does anyone else think? It isn't constantly green, it kinda cycles from slowling gainin green lines and then loosing them.