Family POLYNOIDAE

Lepidonotus melanogrammus

Museums

Museum list

Regional Maps

Family POLYNOIDAE

Scale Worm

Compiler and date details

Jan 2011 - P. Hutchings & M. Yerman, Australian Museum, Sydney, New South Wales, Australia

31 July 2003

Introduction

Polynoids are commonly known as scale-worms because their dorsum is covered by ornamented scales (referred to as elytra). They have a well-developed head with numerous sensory appendages, few body segments and well-developed parapodia. Polynoids are found in most habitats and depths from the intertidal to the deep sea and from the tropics to polar latitudes. They are not often present in highly estuarine habitats. One species may be partially pelagic. A number of distinctive taxa are known only from hydrothermal vents. Polynoids are active carnivores, and the most common prey are amphipod crustaceans, although most small invertebrates are eaten, and algae also occur in gut contents. Many polynoids are commensal on other invertebrates, especially echinoderms, stony corals, octocorals, sponges and within the tubes of other polychaetes. Species with smooth scales have often been shown to have commensal associations and those with ornamented scales to be free-living. An introduction to the literature on commensalism in polynoids is provided by Hutchings (2000).

Figures of ~28 genera and ~87 species were given by Beesley et al. (2000: App. 1) for representation of the family in Australian waters, and 165 genera and 748 species worldwide. This database includes 84 species from 32 genera.

Polynoid diversity is difficult to assess, both because of the rapid description of new taxa and the uncertain status of many genera and the 19 subfamilies. Pettibone (1982) estimated polynoid diversity globally at about 120 genera and 600 species. Additional studies since then bring the total to about 165 genera and 748 species. The Polynoidae is thus among the most speciose and most morphologically diverse of polychaete families. Clearly, many Australian polynoids remain undescribed and many existing records will require reassessment within a revised generic classification.

See Hutchings (2000) for detailed treatment of the family.

Database Notes

proof read against Day & Hutchings 1979 by RW
updated from Hanley, Hanley & Burke, Pettibone, Hartmann-Schröder, Kudenov, Monro & Augener papers by RTJ
checked against DELTA CD, 2003 by RTJ

Diagnosis

General features. Body shape vermiform; dorsoventrally flattened; segments numerous (more than about 15), or few (typically 7 to 14) (rarely); regionation absent. Epidermis more-or-less smooth, or papillate, irregularly arranged papillae. Pygidium simple ring or cone. Pygidial appendages present; one pair of cirri.
Head & head structures. Head discrete and compact, dorsal to mouth; anterior to and distinct from the first segment, or level with or posterior to the first segment. Prostomium rounded to oval (anteriorly truncate); anteriorly incised. Facial tubercle absent. Eyes present; two pairs; situated on prostomium; compound with lenses. Prostomial antennae present; paired arising anterolaterally, or include paired anterolateral ones and single medial one; consist of basal ceratophore and distal ceratostyle. Palps paired; unarticulated; ventrolateral. Nuchal organs indistinct paired dorsolateral patches. Peristomial ring absent.
Pharynx & pharyngeal apparatus. Foregut a muscular axial pharynx; with two pairs of jaws; fang-like; distal ring of papillae present.
Body segments & parapodia. First segment chaetigerous (dorsal and ventral cirri enlarged and elongated). First chaetiger without external chaetae, or with notochaetae only; anteriorly directed and wrapping around head. Parapodia biramous with prominent parapodial lobes; notopodial lobes represented by at least one chaetal lobe; neuropodial lobes represented by at least one chaetal lobe. Dorsal cirri modified as elytra (may include cirriform ones as well). Elytra smooth or ornamented, without concentric rings; occur on alternate chaetigers anteriorly, present on all chaetigers or absent posteriorly. Ventral cirri present, cirriform or tapering. Branchiae absent, or present (rarely); arise from parapodia; occur on at least some chaetigerous segments; digitiform.
Chaetae. Notochaetae present. Aciculae present; in both dorsal and ventral positions (=noto- and neuroaciculae). Capillary chaetae hair-like; spinose, or corn-eared. Spines present in most or all chaetigers; in both notopodia and neuropodia; with series of rings or half-rings of spinelets, or slightly curved and more-or-less smooth. Hooks absent.
Tube & burrow. Tube absent or unconsolidated. Burrow traces absent.

The above description was generated from: 'C.J. Glasby & K. Fauchald (2002 onwards). POLiKEY. An information system for polychaete families and higher taxa: Version 1: September 2002.'
(See ABRS website: Online Resources: Polikey, for Version 2, released June 2003)