PORT PHILLIP BAY


Hydroid 

Orthopyxis angulata Bale, 1914

View scientific description and taxonomy

Scientific Details

Family level detail.
Hydroids with a simple bell-shaped (campanulate) hydrotheca without operculum. Apertural rim of hydrotheca may be smooth, toothed, crenulated or cuspate. Gonophores protected by a gonotheca. Hydroids of the family Campanulariidae are common throughout the world. Many species form large, spreading colonies comprising many simple stems arising from a creeping network of stolons. Other species from large, multi-branched colonies, usually lacy in appearance. Medusae range in structure from primitive eumedusoids that swim only feebly to fully formed free-swimming medusae.

Genus level detail.
Colony stolonal, hydrotheca campanulate, laterally flattened, oval in cross section with thickened wall, a spherule below hydrotheca, rim of hydrotheca smooth or weakly cuspate, gonophore eumedusoid, retained in a gonotheca. Orthopyxis is typified by the flattened hydrothecae. There are several closely related Australian species which can only be distinguished by microscopic examination of the hydrotheca and gonotheca.

Species identification.
Hydrorhizal stolons flat and ribbon-like. Single smooth stems (pedicels) borne on hydrorhiza. Hydrotheca conical, flattened, walls conspicuously thickened, aperture faintly scalloped to smooth. Gonotheca larger than hydrotheca, borne on hydrorhiza, laying flat on substrate, ovate, terminal aperture with a blunt spine at each side, releasing a eumedusa that cannot swim. Female eumedusa with rows of eggs. Colour: colony white, gonotheca cream to white. Up to 3 mm high.

Taxonomy

Phylum:
Cnidaria
Class:
Hydrozoa
Subclass:
Leptothecatae
Order:
Proboscoida
Family:
Campanulariidae
Genus:
Orthopyxis
Species:
angulata

General Description

Colony of individual polyps (hydranths) joined by root-like network of tubular stolons at the base. Colony shape is single stems. Colour: colony white, gonotheca cream to white. Up to 3 mm high.

Biology

Colonies of this species grow annually and are fertile in summer.

Habitat

On fronds of brown kelps in moderate shelter.

Reefs

Distribution guide

Southern Australia.

Species Group

Hydroids

Depth

Shallow (1-30 m)

Water Column

On or near sea floor

Max Size

3 mm

Diet

Plankton or Particles

Harmful

Generally not harmful but still able to sting bare skin.

Commercial Species

No

Identify

Conservation Status

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

Author

article author Watson, J.

Jan Watson is a consultant with expertise in hydroid taxonomy.

citation

Cite this page as:
Watson, J., 2011, Hydroid, Orthopyxis angulata, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 23 Jul 2017, http://portphillipmarinelife.net.au:8098/species/7131

Text: creative commons cc by licence