Pectinaria australis

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Pectinaria australis

Scientific classification

Kingdom:	Animalia
Phylum:	Annelida
Class:	Polychaeta
Order:	Canalipalpata
Family:	Pectinariidae
Genus:	Pectinaria
Species:	P. australis

Binomial name

Pectinaria australis
Ehlers, 1904

Pectinaria australis is a polychaete worm of the family Pectinariidae, endemic to New Zealand where it is the only pectinariid species. Species in this family are known as ice cream cone worms.

Pectinaria australis is a short, conical, blunt-headed mainly colourless worm. It builds its delicate tube home out of a thin layer of sand grains cemented by secretions of the worm's body. The tube, which is up to 50 mm long, is built with exquisite care, each sand grain being selected and cemented in place to a thickness of only one sand grain. The tube is tapered, matching the shape of the worm, and sometimes slightly curved.

It is found both intertidally on sheltered sandy shores, and at depths of up to 70 metres, buried obliquely head-down in the substrate with only the tip of the cemented sand grain cone visible. The head bears two groups of large, slightly curved, golden bristles (digging chaetae), and numerous extensible tentacles. Immediately behind the head are two pairs of little comb-like gills, bright red with blood. The bristles are used to loosen and turn over the deposit, and the tentacles collect particles for food and for tube building. Water is circulated through the cavern and tube, seemingly in either direction, by flapping the parapodia on the sides of the body. The animal moves, with its tube, though the substrate, but only very slowly.

Populations tend to be aggregated, and sporadic from year to year, with adults densest just subtidally in shallow harbours. Density may increase around sources of organic pollution and in eelgrass beds, but Pectinaria australis is also found in clean sand where population density is likely to be less than 50 per square metre. The life cycle is short, approximately one to two years.

When handled Pectinaria australis produce a copious clear mucus, perhaps as a defense strategy.