PORT PHILLIP BAY


Fan worm 

Euchone variabilis Hutchings & Murray, 1984

View scientific description and taxonomy

Scientific Details

Family level description.
Sabellidae are aptly known as fan worms for the crown of feathery radioles which are used to filter particles from the water. The thorax has 8 segments in most sabellids, followed by a variable number of abdominal segments; the two regions are distinguished by a reversed arrangement of dorsal and ventral chaetal bundles. Sabellidae (except for one uncommon tropical genus) make flexible tubes of parchment or mucous. There is no operculum sealing the end of the tube when the worm retracts.

Species level technical description.
Branchial lobes fused dorsally. Radioles few, 4-9 pairs. Palmate membrane present. Radiolar flange radiolar flange not forming expanded rounded flanges at tips of radioles. Radiolar eyes absent. Posterior peristomial ring collar present. Peristomial eyes absent. Dorsal lips with dorsal radiolar appendages. Lacking dorsal pinnular appendages. Thorax with 8 chaetigers. Glandular girdle on chaetiger 2 present. Thoracic interramal eye spots absent. Abdomen with 17-29 chaetigers. Abdominal interramal eye spots absent. Pygidial eyes absent. Anal depression present, occurring over 7-14 abdominal chaetigers, 10-17 abdominal chaetigers preceding anal depression. Marginal flange surrounding anal depression. Notochaetae of chaetiger 1 comprise a bundle of 2 rows similar to remaining thoracic notochaetae. Superior thoracic notochaetae elongate, narrowly hooded. Inferior thoracic notochaetae, posterior row (chaetiger 4) broadly hooded. Teeth of thoracic uncini equal in size in series above main fang. Breast poorly developed, chaeta acicular in appearance (perhaps with a small swelling proximal to the main fang). Handle very long, at least 4 times length of neck of uncinus. Thoracic neuropodial companion chaetae present. Abdominal notopodial uncini with a distinct main fang and several smaller teeth above. Breast well developed. Handle absent. Anterior abdominal neurochaetae, posterior row spinelike. Posterior abdominal neurochaetae, anterior row modified elongate, narrowly hooded

Taxonomy

Phylum:
Annelida
Class:
Polychaeta
Order:
Sabellida
Family:
Sabellidae
Genus:
Euchone
Species:
variabilis

General Description

In members of this genus there is a distinct anal depression forming a spoon-like concavity over the posterior-most segments. This species has the abdominal depression with a marginal flange and occupying 7-14 abdominal chaetigers. Body up to about 1 cm long.

Biology

This species is known as a fan worm for the crown of feathery radioles which are used to filter particles from the water. There is no operculum to seal the end of the tube when the worm retracts.

Habitat

Port Phillip Bay and other similar coastal habitat, inshore and continental shelf.

Reefs

Soft substrates

Distribution guide

Southern Australia.

Species Group

Worms Fan worms

Depth

Shore (0-1 m)
Shallow (1-30 m)

Water Column

On or near sea floor

Max Size

1 cm

Diet

Plankton or particles

Commercial Species

No

Global Dispersal

Native to Australia

Species Code

MoV 1802

Identify

Conservation Status

  • DSE Advisory List : Not listed
  • EPBC Act 1999 : Not listed
  • IUCN Red List : Not listed

Author

article author Wilson, R.

Robin Wilson is a Senior Curator of marine invertebrates at Museum Victoria.

citation

Cite this page as:
Wilson, R., 2011, Fan worm, Euchone variabilis, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 15 Dec 2017, http://portphillipmarinelife.net.au:8098/species/11161

Text: creative commons cc by licence