PORT PHILLIP BAY


Hydroid 

Symplectoscyphus indivisus (Bale, 1882)

View scientific description and taxonomy

Scientific Details

Family level detail.
Colonies may be unbranched or branched and always with two rows of hydrothecae on opposite sides of stem, attached to stem and branches by part of their length. Hydrothecae bilaterally symmetrical, usually with a cuspate aperture with a segmented operculum. Gonophores are sporosacs female producing eggs and the male producing sperm, and protected by a gonotheca. The family Sertulariidae includes many genera and species and is known is a world-wide ranging from the tropics to arctic seas. They occur in all habitats from the intertidal zone to the deepest ocean and are very abundant in cool temperate seas southern Australia. Species range from small simple stems with a few hydrothecae to large, complexly branched pinnate colonies with hundreds of hydrothecae.

Genus level detail.
Stems simple or branched, hydrothecae alternate, tubular, with three marginal cusps, operculum of hydrotheca pyramidal, gonotheca barrel-shaped, deeply ridged with distal neck. Species of Symplectoscyphus are widespread in southern Australian seas although some are small and cryptic and therefore not easily seen. The three marginal cusps of the hydrotheca are distinctive.

Species identification.
Hydrorhiza comprising stolons creeping on substrate. Stems of older colonies sometimes with one or two straggling branches. Hydrothecae alternate along stem and branches, tubular, widest at base, narrowing slightly to margin, body shallowly corrugated, margin with three sharp cusps, Gonothecae along stem, larger than hydrotheca, barrel-shaped, deeply concentrically ridged, narrowing to aperture, apex with three sharp spines. Female gonophore with eggs, male with sperm. Colour: colony white, buff or yellow, eggs yellow to pink. Up to 1.5 cm high.

Taxonomy

Phylum:
Cnidaria
Class:
Hydrozoa
Subclass:
Leptothecatae
Order:
Conica
Family:
Sertulariidae
Genus:
Symplectoscyphus
Species:
indivisus

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, buff or yellow, eggs yellow to pink. Up to 1.5 cm high.

Biology

These hydroids are widespread in southern Australian seas although some are small and cryptic and therefore not easily seen. Their colonies grow throughout year.

Habitat

On algae and invertebrates, common in sheltered oceanic waters and bays.

Reefs

Distribution guide

New Zealand and south-eastern Australia.

Species Group

Hydroids

Depth

Shallow (1-30 m)

Water Column

On or near sea floor

Max Size

15 mm

Diet

Plankton or Particles

Harmful

Generally not harmful but still able to sting bare skin.

Commercial Species

No

Global Dispersal

Recorded in Australia

Species Code

MoV 3478

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, Symplectoscyphus indivisus, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 25 Feb 2025, http://136.154.202.208:8098/species/7141

Text: creative commons cc by licence