I'm not going to make a habit of this as I think everyone should buy their own books and do their own research, but this is from "A PocketExpert Guide Marine Invertebrates" which I recommend every reef keeper gets. This is what it says about Feather Dusters:
....Feather duster worms are from four common families within the Class Polchaeta, one of the three major classes of the annelids (segmented worms). Although species from each family have some unique attributes, there are many similarities in the biology of all fether duster worms.
Common Characteristics:
All worms in this group have crowns of tentacles used in feeding - these arrangements are the so-called feather dusters.
These crowns are comprised of branched tentacles, with each tentacle's branches arranged like the filaments along a feather
All feather dusters feed on fine particlate organic material, such as phytoplankton and bacterial aggregates, suspended in the water.
All have mechanisms and structural modifications in the tentacles that allow sorting of the filtered particles.....
.... Generally, feather duster worms will do best in areas with moderate to high currents. Lighting is immaterial to their health.........
.......Identification of these worms to family is easy - basically it involves examining the tube. identification to species is also easy for a few common large species.
Family Differences
Family Sabellidae: Tubes are made of a relatively soft material, which may be very flexible or about as stiff as cardboard. Sabellid worms range from very small to quite large. The biggest are over 36 in.(91cm) long, with tentacle crowns over 5 in (13 cm) in diameter. In the aquarium world, these are the animals commonly called "feather duster worms," although the other families have similar feathery crowns. Some smaller species reproduce asexually very well in captivity, forming large colonies.
Family Serpulidae: Tubes are made of calcium carbonate and are often attached to rocks or other substrate material. They frequently have a doubled crown of tentacles, sometimes forming a doubled, tapered helix. They often have an operculum, or plug, that fits into the tube and seals it when the worm has withdrawn. In the aquarium world, these are commonly called "hard-tubed feather dusters", "Christmas tree worms" or "Coco worms".
Family Spirorbidae: These diminutive worms live in small tubes often attached to rocks or growing on the sides of the aquarium. The tightly spiraled tube is seldom over 0.2 in.(5 mm) in diameter. The tentacle cown is bright red or red-orange, but is clearly seen only with magnification. they are and reproduce well in captivity, but are probably never intentionally purchased.
Family Sabellaridae: Tubes are made of cemented sand or other substrate grains. The tentacle crown is generally smaller and less brightly coloured than in the other families. The individual worms seldom exceed 4 in (10cm) in length, but collectively they may form reefs of cemented worm tubes that are hundreds of yards long and up to 66ft (20m) high. These worms are seldom seen in captivity because the aggregations of tubes are simply too difficult to break for the animals to be easily collected. However, individuals may enter tanks attached to live rock.