Ophiodromus pugettensis

Ophiodromus pugettensis (Johnson, 1901)

Common name(s): Bat star commensal worm

Synonyms: Podarke pugettensis, Ophiodromus pugettensis

Phylum Annelida

Class Polychaeta

Subclass Palpata

Order Aciculata

Suborder Phyllodocida

Superfamily Nereidacea

Family Hesionidae

Ophiodromus pugettensis, about 2 cm long, from a sponge in Padilla Bay.

(Photo by: Dave Cowles, July 2, 2010)

Description: As with all members of family Hesionidae, this species is a small to moderate-sized worm wich has most segments wider than long. Its capillary setae are not cross-barred. Its notosetae do not extend nearly to the dorsal midline. The prostomium does not extend back dorsally onto posterior segments as a caruncle. It does not have a cluster of tentacles around the mouth, though it does have prostomial palps and 2-3 pairs of antennae on the prostomium as well as tentacular cirri on the peristomium. Both the prostomial and the peristomial appendages can detatch, and the worm fragments readily. They have 1-2 pairs of eyes Compound setae are present. Ophiodromus pugettensis has 2 pairs of eyes, 3 prostomial anetnnae, and 6 pair of tentacular cirri which hook to the peristomium laterally and ventrally. The ventral cirri are shorter than the lateral ones. It has no jaws or teeth on the eversible pharynx. The parapodia are biramous, and the notopodia have setae of two or more kinds in distinct fascicles. The first notosetae are on setiger 3 or 4. The color of the animal is dark brown, reddish brown, purple, or black; sometimes pale. The pygidium is usually white. Length to 4 cm.

How to Distinguish from Similar Species: Podarkeopsis bervipalpa has 8 pairs of tentacular cirri. Micropodarke dubia and Kefersteinia cirrata have only 2 prostomial antennae..

Geographical Range: Japan, southern Alaska to Gulf of California (Mexico); Peru.

Depth Range: Intertidal and subtidal

Habitat: Free-living on muddy bottoms or commensal on the ambulacral grooves of seastars such as Patiria miniata. Less common seastar hosts include Luidia foliata, Pteraster tesselatus, and Oreaster occidentalis. It may also be found on moon snail shells occupied by hermit crabs.

Biology/Natural History: This species is attracted to sea stars by chemoreception. Up to 20 can be found on a seastar host, and coexist peacefully with each other. They reside in the ambulacral groove or crawl over the oral surface. They readily crawl onto another host if it is nearby, or can often be found on the mud bottom without a host. Freeliving individuals do not seem interested when presented with a seastar host. The worms eat diatoms, harpactacoid copepods, and other small benthic invertebrates. They can live in polluted water low in oxygen but are most common in clean water. This individual was found by Michael Kutzner when it exited a Mycale adhaerens sponge from Padilla Bay.

References:

Dichotomous Keys:
Carlton, 2007
Kozloff 1987, 1996

General References:
Kozloff, 1993
Lamb and Hanby, 2005
Morris et al., 1980
Ricketts et al., 1985

Scientific Articles:
Hickick, J.F. and D. Davenport, 1957. Further studies in the behavior of commensal polychaetes: Three species of commensal polychaetes, Ophiodromus pugettensis, Arctonoe fragilis, and A. vittata, are attracted by chemicals released by their respective hosts. Biological Bulletin 113: pp 397-406.

Lande, R. and D.J. Reish, 1968. Seasonal occurrence of the commensal polychaetous annelid Ophiodromus pugettensis on the starfish Patiria miniata. Bulletin of the Southern California Academy of Sciences 67: pp 104-111

Schaffer, P.L., 1979. The feeding biology of Podarke pugettensis (Polychaeta: Hesionidae). Biological Bulletin 156: pp 343-355

Pettibone, M.H., 1953. Some scale-bearing polychaetes of Puget Sound and adjacent waters. University of Washington Press, Seattle, WA. 89 pp.

Web sites:

General Notes and Observations: Locations, abundances, unusual behaviors:

A closeup of the head. Note the prominent eyes, the 5 antennae from the prostomium, the tentacular cirri from the first few segments, and the very long dorsal cirri which extend from the parapodia. A piece of debris is attached to one of the tentacular cirri. Photo by Dave Cowles

Authors and Editors of Page:
Dave Cowles (2010): Created original page
CSS coding for page developed by Jonathan Cowles (2007)