Uh, guys. I understand the hitchhikers but purchasing an animal and placing it in your aquarium when you do not know how to care for it smacks of cruelty.
The care and keeping of feather duster worms is well known and quite easy. These worms are NOT photosynthetic and do not need light, but they do have eyes and will respond to light and movement.
To quote maine biologist Dr. Ron Shimek: "Feather dusters need a lot of food, and if the food is not present, will starve for a while and then shed the tentacle crown." Dusters also shed their crown when they are stressed out from poor water conditions, such as high nitrates (more than 10ppm), or if they are placed in too little or too high flow. I have mine in just enough flow to wave their feathers gently.
Feather dusters are filter feeders, and eat the phytoplankton in suspension in the water column. Unless you a) dose phytoplankton or b) you have a large system with plenty of LR and light or no skimming (skimming removes phytoplankton), your dusters will almost certainly starve to death. I dose DT's Live Phyto in my tanks.
As with just about any invertibrate, they appreciate full-strength seawater (~1.025 specific gravity) and natural reef temperatures (78-82).
You'll find tons of info just by searching Google. Here is the article I quoted:
http://www.dtplankton.com/Feather_dusters.htm.
Sorry if I come across as a jerk but I hate to see any animal die from ignorance of their needs.
