FYI - I don't think that your bristle worms are a worry about feather dusters instead you need to worry about the following c&p from and article I have about them.
Predators
It is important to consider leaving out potential predators of feather duster worms when designing an aquarium to house them. Butterflyfishes quickly decimate them as the feather duster crown is a delicacy they really appreciate for dinner, lunch, and breakfast, while the worm left in the tube is finished for desert. Crabs of many kinds find great pleasure first in making the crown withdraw, then pinching the tube, squeezing the life out of the worm and finishing it off in a single session. Some (but not all) wrasses will make short work of feather dusters, eating them so quickly that the worm probably hardly realizes it is no longer safely in its tube. Some hawkfishes likewise will eat them. Serpent stars are generally safe, but they may pick apart a colony of Bispira brunnea, especially when the colony is first introduced to the aquarium and it smells like your fish-food flavored finger tips.
Hope that helps
Thomas
