Fan worm 

Branchiomma sp. MoV 3639

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 numerous, usually more than 8 pairs and increasing with size of worm. Palmate membrane present. Radiolar flange radiolar flange forming expanded rounded flanges at tips of radioles. Paired stylodes well developed. Radiolar eyes present as paired compound eyes throughout length of radioles. Anterior margin of peristomial ring unmodified, of low, even height all around. Narrow, about as long as wide. Distal end entire. Posterior peristomial ring collar present. Dorsal lips with dorsal radiolar appendages. With dorsal pinnular appendages. Thorax with 8 chaetigers. Glandular girdle on chaetiger 2 absent. Thoracic interramal eye spots present. Abdominal interramal eye spots present. Pygidial eyes absent. Anal depression absent. Notochaetae of chaetiger 1 comprise a bundle of 2 rows similar to remaining thoracic notochaetae. Superior thoracic notochaetae elongate, narrowly hooded. Inferior thoracic notochaetae, anterior row (chaetiger 4) absent. Inferior thoracic notochaetae, posterior row (chaetiger 4) spinelike. Teeth of thoracic uncini equal in size in series above main fang. Breast well developed, resulting in a Z-shaped avicular appearance. Handle very short, much shorter than 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 short. Posterior abdominal neurochaetae, anterior row spinelike.



General Description

In members of this genus the radioles generally have some pinnules enlarged to form macrosylodes and have the dorsal collar margins separated by a wide gap. Thoracic interramal eye-spots are present. Body up to about 1 cm long.


Brianchiomma sp. is very common in shallow waters where algal turfs form on reef, however the genus has never been reviewed systematically in Australia and the identity of our local species is uncertain.


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


Distribution guide

Southern Australia.

Species Group

Worms Fan worms


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

Water Column

On or near sea floor

Max Size

1 cm


Plankton or particles

Commercial Species


Global Dispersal

Native to Australia

Species Code

sp. MoV 3639


Conservation Status

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


article author Wilson, R.

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


Cite this page as:
Wilson, R., 2011, Fan worm, Branchiomma , in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 29 Mar 2020,

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