PORT PHILLIP BAY


Hydroid 

Orthopyxis caliculata (Hincks, 1853)

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.
Colonies cmprising many hydrothecae connected by a ribbon-like hydrorhiza loosely adherent to substrate. Stems (pedicels) annulated throughout their length. Hydrotheca conical, slightly flattened, about 0.5 mm long, inclined to substrate, with thickened walls, apertural rim smooth. Gonotheca larger than hydrotheca, ovate, flattened on substrate, containing a primitive eumedusa that cannot swim. Female with rows of eggs. Colour: colonies transparent white, gonophores cream. Up to 3 mm high.

Taxonomy

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

General Description

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

Biology

This is a common species in southern Australia. Colonies grow annually and are fertile in spring and summer.

Habitat

On fronds of brown algae and invertebrates 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

Species Code

MoV 3455

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 caliculata, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 23 Sep 2017, http://portphillipmarinelife.net.au:8098/species/7132

Text: creative commons cc by licence