Spionid Polychaete

Spionids are a family of small, thin polychaete worms that build their tubes from sand and other small particles. These Spionids have two feeder tentacles that they stretch out to find food. They are beneficial scavengers that feed on detritus and small organic particles.

If anyone has any pictures or additional information they would like to share on the Spionid Polychaete, please feel free to post it here.

[jman785]

http://www.pac.dfo-mpo.gc.ca/sci/shelldis/pages/sbpoy_e.htm

Check that out, apparently this little buggers, cause quite of a bit of trouble to oyster farms.

Click Expand to read the rest of the quote from Reefs.org

Spionids are a family of small, thin polychaete worms that either burrow, or form delicate tubes composed of sand or mud (e.g., Polydora, Spio, Streblospio). The easiest feature with which to identify a spionid polychaete is the presence of two long, coiled peristomial palps (feeding "tentacles" originating from the "head") which are grooved. Most species use these grooved palps to selectively scavenge detritus and tiny organic particulates from the surfaces around their tube. Although not quite as versatile with their "tentacles" as their cousins, the Terebellids, they feed in a very similar manner (discussed in Terbellidae, below). You will most likely not see the worm, but instead see only the two tiny, hair-like palps swinging back and forth in the water flow searching for food particles.

These worms are uniformly small (rarely exceeding 2 mm in diameter, about equal to a pencil lead, or a few cm in length), and if you see a couple of palps waving about from a worm that is quite thin, but a couple of inches in length it is most likely Phyllochaetopterus or Mesochaetopterus (see Chaetopteridae, at the beginning of last month's article) rather than a spionid polychaete. In any case, neither group is likely to be harmful to your reef aquarium, so there is no need to attempt to remove them.

Having said this, however, there are some spionids that burrow into any calcareous substrata, including the shells of molluscs, to make a safe home. Even these species are not dangerous to most large molluscs in small numbers, but if they become plentiful enough, they can weaken the shell to the extent that it easily breaks. If you notice many small pairs of palps protruding from holes in the shell of your prize Tridacna, you may want to kill the worms by heating a large sewing needle, and inserting it gently into the hole (MAKE SURE you don't go through the shell and touch the clam!! You only want to kill the worm!). Many worms form their tubes on or in between structures of other animals, so don't panic if you see palps extending from the side of an animal. If the worms are not plentiful, or are not actually embedded IN the shell of the animal, you can (and should) ignore them as harmless scavengers. It is only when a calcareous burrowing species reaches high density that members of this family can cause problems.