NIWA Guide to Polychaeta | Shore polychaetes | Shell polychaetes
Shell worm Polydora haswelli Spionidae (spionid)
Spionida (Annelida: Polychaeta)
Polydora  haswelli  Blake & Kudenov, 1978.   Family Spionidae  
     Polydora haswelli lateral head in life
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 Identification tips:    Morphology unremarkable. Distinctive colour pattern(s) present; black-banded palps but without palp groove pigment, and dorsal black pigmentation on caruncle and first few segments.
 Habitat: Intertidal marine, or inshore marine embayment, or marine shelf. Known from mollusc shell. In bivalves. In shell blisters, debri packed. Recorded from living shells of New Zealand commercial shellfish: Crassostrea gigas, Pecten novaezelandiae, Perna canaliculus. Occurrences in empty/dead shell also never reported. Tube lining present as packing within mud blister. Tube chimney present as glued debri/sand-grains.
 Nomenclature: Genus Polydora in Family Spionidae. Polydora haswelli. Described by Blake and Kudenov, published in 1978, as Polydora haswelli. Type locality: New South Wales, Australia, Sydney Harbour. Other synonyms: none recorded. Close to, or possibly same as, Polydora neocaeca from east coast North America.
 Description:  Head region: Prostomium tip weakly notched. Occipital antenna absent. Caruncle extends to anterior chaetiger 4; separate mid-dorsal organ absent. Colouration: Eyes present, two pairs. Dorsal pigmentation pattern present; dark anterior dorsal pigmentation present. Dark anterior pigmentation on head. White (or yellow white) anterior dorsal pigmentation absent. Palp banding black spots. White mid-body or posterior dorsal pigmentation absent. Other colouration includes white pygidial fan. Branchiae, chaetae, and pygidium: Branchiae adjoining parapodia 7 and following; longest branchiae on chaetiger 10 or later; near body end branchiae present. Anterior gut gizzard-like structure absent. Hooded hooks begin chaetiger 7; bifid, hook shaft constriction (manubrium) present, anterior hooded hook main fang more or less oriented at right angles to the shaft with wide angle to apical tooth. Alternating capillaries adjacent hooded hooks absent; neurochaetal inferior chaetae below hooded hooks absent. Chaetiger one notochaetae absent; notopodial lobe present. Chaetiger 5 elongated relative to adjacent segments. Chaetiger 4 thickened chaetae (similar to those of chaetiger 5) absent. Chaetae of chaetiger 5 'upper' (or 'posterior') row falcate with subterminal flange as a lateral tooth, 'lower' (or 'anterior') row are bilimbate 'companion' chaetae (very flattened tips). Superior notochaetae of chaetiger 5 present. Inferior neurochaetae of chaetiger 5 present. Posterior notochaetal spines absent. Pygidium flattened disc/saucer-rim with dorsal notch/gap. Pygidium large, distinctly wider than last chaetigers.
 Dimensions: Length 24 mm. Width 1 mm. Segment total 120. Palps extend to about chaetiger 13. Slender.
 Reproduction: Active planktonic dispersal present.
 Distribution:  World distribution includes New Zealand and elsewhere. Global distribution includes New Zealand mainland, Australia, within south east coast and Tasmanian zone. Within New Zealand confirmed records are known for the Hauraki Gulf, Firth of Thames, and Coromandel Peninsula inshore waters. The occurrence of Polydora haswelli further southwards in New Zealand is not yet confirmed..
 Remarks:  Polydora haswelli is a penetrative shell-blisterer which is probably going to be an ongoing severe pest to the shellfish industry. It is the only species with verified ability to cause blistering in Perna canaliculus. Morphologically it is similar to Polydora websteri.
 Biology: Polydora haswelli is new to New Zealand, and little is known of its biology in Australia from where it was first described. It has been reported in popular articles (eg Skeel) as a pest species there. Feeding group: Surface deposit/filter-feeding.
 Best References:   Biology: Read and Handley (2004) (In press) Shell-blister damage in cultured Perna canaliculus mussels and the role of Polydora haswelli (Polychaeta: Spionidae).. New Zealand Journal of Marine and Freshwater Research 38: Taxonomy: Read (1975) Systematics and biology of polydorid species (Polychaeta: Spionidae) from Wellington Harbour. Journal of the Royal Society of New Zealand 5:395-419.

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The information provided by this page and by the pages of the "more information" links is held in a structured form for rapid and frequent updating and improvement. Descriptive text is compiled from a number of database fields, some of which may occasionally be empty.
Data last edited 20/07/2004  (dd/mm/yy), and page last generated by G. Read, 25/07/2004  (dd/mm/yy)