physonect siphonophore Bargmannia sp.

Bargmannia species are the only physonect siphonophores with siphosomal (tail-end) tentacles and they also lack dactylozooids (defensive stinging individual zooids) [3].

Siphonophores are swimming/floating colonies consisting of different zooids specialized for feeding, sensing, flotation, and reproduction [1]. Siphonophore colonies bud from a stem whose gastrovascular canal is continuous with the canals of all the zooids in the colony [1].

Physonect siphonophores have an apical gas-filled float with a budding zone on either side of the base [1].

Siphonophores occur throughout Antarctica and subantarctic waters, with warm-water species observed in high latitudes during the spring and summer and cold-water species surviving at low latitudes during the winter [2].

Siphonophores are active predators, feeding on other plankton like fish larvae and krill [2].

1: A General Guide to the Metazoan Zooplankton Groups of the Southern Ocean. D O'Sullivan and G Hosie. ANARE Research Notes 30 (Australian National Antarctic Research Expedition). Kingston, Tasmania, Australia: Australia Dept of Science and Technology, Antarctic Division, 1985; 2: Antarctic Siphonophores from Plankton Samples of the United States Antarctic Research Program : ELTANIN Cruises for Spring, Summer, Fall, and Winter (Cruises 3-5, 8-23, 25-28, 30, 35, and 38). A Alvarino, JM Wojtan, and MR Martinez. Washington DC: American Geophysical Union, 1990; 3: Bulletin of the Natural History Museum. Zoology Series 65(1):51-72, 1999

Text ©Peter Brueggeman. Photograph ©M Dale Stokes. Photograph may not be used in any form without the express written permission of M Dale Stokes.