Halosydna brevisetosa

The Eighteen-scaled Worm

Phylum Annelida
Class Polychaeta
Order Phyllodocida
Family Polynoidae
Genus Halosydna
Species brevisetosa

Description: Length of 11 cm and more than 1 cm wide; gray to brownish gray or reddish brown, usually with transverse bands; each scale has a pale dot; 18 pairs of oval scales; one pair of antennae and one single antenna of a different length.

Habitat: Found free-living on floats, among mussels, on algal holdfasts or growth on rocks and pilings.

Natural History: This worm is often involved in commensal relationships, most commonly with polychaete worms in the family terebellidae. When found on floats, this worm is probably free-living.