PORT PHILLIP BAY


Ragworm 

Simplisetia aequisetis (Augener, 1913)

View scientific description and taxonomy

Scientific Details

Family level description.
Nereididae are polychaetes with many uniform segments, without strongly differentiated body regions. The prostomium (head) has one pair of antennae, one pair of articulated palps, and two pairs of eyes. Four pairs of unjointed cirri emerge from the next segment behind the prostomium. Mouthparts comprise an eversible pharynx with one pair of terminal jaws, although these are usually only visible by dissection.

Species level technical description.
Prostomium with entire anterior margin. Maxillary ring of pharynx with conical paragnaths: Area I: 1-4; II: 10-36; III: 17-45; IV: 12-53. Oral ring paragnaths absent. Dorsal notopodial ligule not markedly elongate on posterior chaetigers. Not markedly broader on posterior chaetigers. Dorsal notopodial ligule not markedly reduced on posterior chaetigers. Prechaetal notopodial lobe present. Dorsal cirrus not terminally attached to dorsal notopodial ligule on posterior chaetigers. Dorsal cirrus length about 0. 75-1 times ventral notopodial ligule at chaetiger 10-20. Neuropodial postchaetal lobe absent. Ventral neuropodial ligule on posterior chaetigers reduced, up to half length of acicular neuropodial ligule. Ventral cirri single. Notopodial homogomph spinigers present. Notopodial homogomph falcigers absent. Neuropodial dorsal fascicle fused falcigers present.

Taxonomy

Phylum:
Annelida
Class:
Polychaeta
Order:
Phyllodocida
Family:
Nereididae
Genus:
Simplisetia
Species:
aequisetis

General Description

In members of this genus there are robust, simple chaetae in which the articulation between shaft and blade is fused; these simple chaetae are usually dark enough to be seen under stereo microscope and are present in the middle buch of chaetae starting at about 12-15. Paragnaths are present, but only on the maxillary ring (closest to the jaws) of the eversible phayrnx. This species can be distinguished from the only other common member of the genus in southern Australia by having numerous (10-20 or more) dark paragnaths on each of Areas II and III of the eversible pharynx. The other common Nereididae species in southern Australian estuaries reaches a large size and has papillae, not paragnaths, it is Australonereis ehlersi. Simplisetia aequisetis occurs in estuarine conditions while Simplisetia amphidonta occurs in fully marine environments. Body up to about 4 cm long.

Biology

This is one of the most common estuarine polychaete species, being found in every estuary in southern Australia, often occurring in vast numbers.

Habitat

Estuaries, typically intertidal to depth of 3 m, occasionally to depth of 10 m.

Seagrass meadows

Soft substrates

Coastal shores

Distribution guide

South-eastern Australia, or south-western Australia.

Species Group

Worms Ragworms

Depth

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

Water Column

On or near sea floor

Max Size

4 cm

Commercial Species

No

Species Code

MoV 1061

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, Ragworm, Simplisetia aequisetis, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 18 Dec 2017, http://portphillipmarinelife.net.au:8098/species/7625

Text: creative commons cc by licence