Fan Worms are not only beautiful additions to a reef aquarium, but are also efficient filter feeders that play an important role in a properly balanced reef system. Due to their feathery appendages, these worms are also known as Feather Duster Worms. These "feathers" are used to actively filter out tiny organic particulate matter from the water column, often missed by our filtration systems. If these particles are not biologically processed or removed, they slowly decay and compromise water quality. By feeding on these organic particles, Fan Worms keep nutrient levels low and help maintain good water quality.
Fan Worms are marine segmented worms that are sessile, attached to rocks or sand by their base. They are a member of the phylum Annelida, which also includes earthworms. Fan Worms are usually of the families Terebellidae (Medusa Worms), Sabellidae (Feather Dusters), or Serpulidae (Christmas Worms). While their close cousins the mobile (Errantia) bristleworms have a body with equal segments (metameres), the sessile bristleworms (Sedentaria) will have body segments of different sizes. Found in nearly all tropical regions of the world, Fan Worms will produce parchment, a skin-like casing made from body secretions, as they burrow into the substrate of choice. Christmas Worms position themselves in such a way that their "host" coral grows completely around the worm, with only its plume (radiole) crown visible. While the Fan Worm is a solitary animal, it is often found in large clusters of individuals.
The plume of Fan Worms can measure up to 10" in diameter on some species, while the worm may range from 2" to 7" long. Primitive eyes allow the worm to quickly withdraw its radiole plume if it detects motion (usually a predator).
The ideal aquarium for Fan Worms is one with plenty of live rock, a sand bed, and invertebrate friendly inhabitants. Feather Dusters should not be kept in reef tanks with Angelfish or Butterflies, which prey on them.
It is important to maintain good water conditions since Fan Worms are unable to tolerate poor water conditions or sudden changes in temperature or salinity. When they are stressed, Fan Worms will shed their feather-like crown but they will re-grow this crown unless the stress is a result of poor environmental conditions. It is very beneficial and possibly necessary to regularly stir the sand in the aquarium, not only to feed the worms but also to aerate the sand bed.
In a fully stocked mature reef aquarium, Fan Worms do not require any supplemental food source and will feed happily upon the available detritus, plankton, and bacteria. If in an environment in which supplemental feeding is necessary, use infusoria or foods designed for filter-feeding invertebrates.
With their wonderful coloration and unusual feather-like appendages, Fan Worms not only add beauty, but also aid in achieving low nutrient levels in the reef aquarium.