PORT PHILLIP BAY


Blue-bottle 

Physalia physalis (Linnaeus, 1758)

View scientific description and taxonomy

Scientific Details

Each Physalia utriculus is a colony consisting of a modified medusa (the float) and clusters of polyps (zooids) which perform different functions (e.g. feeding, defence, reproduction). The float (pneumatophore) is double-walled and filled with gas. Gastrozooids are short feeding polyps with a mouth. Dactylozooids look similar to gastrozooids but have no mouth and possess tentacles, some of which are longer fishing tentacles. All tentacles bear stinging buttons containing many nematocysts (stinging cells). Gonophores are small sacs containing gametes of each sex. There is some confusion about the genus Physalia in Australia. Currently the more common blue bottle Physalia utriculus is differentiated from the large Pacific man-o-war (Physalia sp.) by the number of fishing tentacles. P. utriculus has one prominent fishing tentacle, while Physalia sp. has multiple fishing tentacles. The number of tentacles increases with development in Physalia sp. causing uncertainty as to whether they are one or separate species. The occurrence of Physalia sp. has so far only been recorded from north Queensland.

Taxonomy

Phylum:
Cnidaria
Class:
Hydrozoa
Order:
Siphonophora
Family:
Physaliidae
Genus:
Physalia
Species:
physalis

General Description

Transparent, clear to blue balloon float with a single prominent, blue tentacle underneath. Float about 6 cm across, tentacles up to 1 m long.

Biology

These animals float on the surface with their tentacles hanging below in the water. The float can be orientated in one of two ways so that individuals are blown to the left (left-sailing) or to the right (right-sailing). This ensures that they do not all get blown in the same direction.

Habitat

Floating on the surface, may drift near shore due to tides and wind.

Open water

Distribution guide

Worldwide.

Species Group

Jellyfishes and allies › Jellyfishes

Depth

Shore (0-1 m)

Water Column

Surface

Max Size

6 cm

Diet

Carnivore

Harmful

Painful sting that requires medical advice. Specimens washed ashore are still able to sting.

Commercial Species

No

Global Dispersal

Recorded in Australia

Identify

Conservation Status

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

Author

article author Browne, J.

Jo Browne is a consultant with expertise in ctenophore and cnidarian taxonomy.

citation

Cite this page as:
Browne, J., 2011, Blue-bottle, Physalia physalis, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 25 Feb 2025, http://136.154.202.208:8098/species/7760

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