Of the 9000 species of annelids, more than 8000 are polychaetes. They are segmented worms and are the most common marine organisms. They can be found lliving in the depths of the ocean, floating free near the surface, or burrowing in the mud and sand of the beach. Some, like Eunice gigantea can reach three meters long. The mobile forms tend to have well-developed sense organs and jaws, while the stationary forms lack these organs, but may have specialized gills or tentacles used for respiration and deposit or filter feeding.

Polychaetes are known by many names: lugworms, clam worms, bristleworms, fire worms, palolo worms, sea mice, featherduster worms, but all  of them have an array of bristles on their many legs called parapodia. The name polychaete means "many bristles". Their many common names show the wide array of body forms found and do not have the same general appearance.(Buchsbaum, R.)

On A Fun Note:
"The delicate beauty of many polychaetes make them a favored subject for photography, and several are named after nymphs and goddesses of Greek myth, such as Nereis (the common "clam worm") and Aphrodite (the "sea mouse")(Buchsbaum, R.)".

Bristleworm (www.arcodiv.org/.../Tomopterus_400x300.jpg)