Polynoidae

Family: Polynoidae

Group: Marine Invertebrate, Species

Scientific Name	Common Name	Summary
Arctonoe pulchra	Red commensal scaleworm	Much less common than Red-banded commensal scaleworm (Arctonoe vittata), but still quite a normal sight on the California sea cucumber (Parastichopus californicus), and an unusual find on other hosts. This species is most easily recognized when it is brick-red and living on California sea cucumber (Parastichopus californicus), but when it is paler and living on other hosts, it can still be identified by the absence of the dark band of Red-banded commensal scaleworm (Arctonoe vittata), or of the ruffled elytra margins of Arctonoe fragilis.
Arctonoe vittata	Red-banded commensal scaleworm	This commensal scaleworm is commonly found on the underside of Leather star (Dermasterias imbricata) and Mottled star (Evasterias troscheli). It is also found on a variety of other hosts, including sea cucumbers and Gumboot chiton (Cryptochiton stelleri). Arctonoe vittata defends its host, and keeps it somewhat cleaner. Arctonoe vittata's "red band" isn't always obvious, but when present is a good indication of the species at hand. Other species of Arctonoe generally have ruffled elytra.
Halosydna brevisetosa	Eighteen-scaled scaleworm	This is a common, aggressive species. The color is quite variable, from light to dark or reddish, but the worm reliably has eighteen pairs of scales. The scales generally have a whitish spot right where the elytrophore meets the plate (O'Clair & O'Clair 1998). An easy place to find this worm is among colonies of tubeworms Vancouver feather-duster worm (Eudistylia vancouveri). This species have robust bodies up to about 80 mm (about 3 inches long) and 13mm (0.5 inches)wide with 37 segments. The large proboscis is armed with four robust jaws. The Armored Scaleworm often crawls on driftwood infested with the Northern Gribble isopod (Limnoria lignorum) and preys on this crustacean. (pg. 162-163, O'Clair & O'Clair. 1998)