Polychaetes are largely marine annelid worms that are a major component of reef ecosystems. Most can be readily distinguished from opisthobranchs by their segmented bodies, leg-like parapodia and bristle-like setae. A few, however, have retractile tentacles lining the body that superficially resemble cerata or are broad and flattened resembling dorids. A close look at the underside of these will reveal the segmentation and setae. They may be predators, scavengers or detritus feeders. A few of the species most frequently mistaken for sea slugs:

Amblyosyllis sp. CP: Maui; April, 2007	Iphione muricata CP: Maui; April, 2005	Spirobranchus giganteus CP: Maui, Nov. 2007

For more information see:   Polychaetes on the Sea Slug Forum