Cyclostomate bryozoan Hornera sp.

Antarctic species of Hornera are found throughout Antarctica, Antarctic Peninsula, subantarctic islands, Tierra del Fuego, and Auckland Islands [1].


Hornera is a cyclostomate bryozoan. Cyclostomates are roughly 30% of the Ross Sea bryozoans shallower than fifty meters and 12% deeper than fifty meters [2]. Compared to cyclostomates, cheilostomate bryozoans are much more numerous in Antarctica where they comprise 85% of bryozoan taxa [2].

Bryozoans are sedentary animals that form colonies of individuals (zooids) by budding. The external skeletal walls of bryozoans are made with calcium carbonate (calcareous). Bryozoan zooids sit in the equivalent of a calcified box with a gated opening from which a feeding structure is protruded to capture small plankton; food is carried to the mouth with cilial hairs and then sucked into the stomach for digestion.

Sea slugs and sea spiders are the usual predators of bryozoans.

1: Biological Reports of the Soviet Antarctic Expedition, 1955-1958. Volume 4. (Rezultaty Biologicheskikh Issledovanii Sovetskoi Antarkticheskoi Ekspeditsii, 1955-1958) Chief editor: EP Pavlovskii. Edited by AP Andriyashev and PV Ushakov. Jerusalem, Israel : Program for Scientific Translations, 1970. pp. 33-83; 2: Biology and Palaeobiology of Bryozoans: Proceedings of the 9th International Bryozoology Conference, School of Biological Sciences, University of Wales, Swansea, 1992. PJ Hayward, JS Ryland and PD Taylor, eds. Fredensborg, Sweden : Olsen & Olsen, 1994. pp. 205-210

Text © Peter Brueggeman. Photographs © Canadian Museum of Nature (Kathleen Conlan). Photographs may not be used in any form without the express written permission of Canadian Museum of Nature (Kathleen Conlan).