polychaete sponge Isodictya erinacea

Isodictya erinacea is found throughout Antarctica, the Antarctic Peninsula, and the Falkland Islands from 30 to 920 meters depth [1,5,6,7,11,12]. The body of I. erinacea is globular, cylindrical, stem- or tree-like, light brown or yellow in color, up to twenty centimeters high, and attached to the substrate by a long strand of spongin [1,5,8,9,10].

Isodictya erinacea can be characterized by its yellow color and spiny appearance with long fibrous spines which are simple or divided [1,9,10].

The surface of I. erinacea has numerous conules in two morphs: short conules or long conules up to nine centimeters long [5,8,10].

I. erinacea is uncommonly seen, being 0.01% of the benthic surface cover at a Cape Armitage site [1]. Four I. erinacea have been observed to grow thirteen centimeters in ten years while four others have shown little or no growth over the same period [4].

Isodictya erinacea may host diatoms within its food-capturing cells that line the passages through which the sponge circulates water; these endobiont diatoms live by consuming carbohydrates produced by the sponge and also by photosynthesis [14,15]. Diatoms produce large amounts of polysaccharids, thus giving the sponge an alternative food source during food- scarce periods [15].This symbiotic adaptation by the diatoms enhances their survival in the low light levels found down deep under the ice (as well as the dark months of winter) [14,15].

Isodictya erinacea has no observed predators [1]. Extracts from I. erinacea suggest that chemical defense is used by the sponge to avoid predation; extracts cause tubefoot retraction in the seastar Perknaster fuscus antarcticus, a common sponge predator [2,13].

An extract from I. erinacea has antibacterial, antifungal, and antiyeast activity [3].

Taxonomic Note: Homoeodictya is a synonym of Isodictya [16]. Isodictya used by Koltun (1976), and Desqueyroux-Faundez (1989) [5,9]; Homoeodictya used by Bergquist (1988), and Hooper and Wiedenmayer (1994) [6,7].

1: Ecological Monographs 44(1):105-128, 1974; 2: Antarctic Journal of the United States 29:151-153, 1994; 3: Antarctic Science 4(2):179-183, 1992; 4: Biologie des Spongiaires, Sponge Biology. C Levi and N Boury-Esnault, eds. Colloques Internationaux du Centre National de la Recherche Scientifique Number 291. Paris : Centre National de la Recherche Scientifique, 1979. pp.271-282; 5: B.A.N.Z. Antarctic Research Expedition, 1929-1931, under the command of Sir Douglas Mawson, Kt., O.B.E., B.E., D.Sc., F.R.S., Reports -- Series B (Zoology and Botany). Volume 9, part 4. Porifera -- Part 1: Antarctic Sponges. VM Koltun. Adelaide : Mawson Institute for Antarctic Research, University of Adelaide, 1976; 6: Marine Fauna of New Zealand: Porifera, Desmospongiae, Part 4 (Poecilosclerida). Bergquist PR and Fromont PJ. New Zealand Oceanographic Institute Memoir 96, 1988; 7: Hooper, JNA & Wiedenmayer, F. Porifera. IN: Zoological Catalogue of Australia. Volume 12. Wells, A, ed. Melbourne : CSIRO Australia, 1994; 8: Sponges of the Antarctic. I. Tetraxonida and Cornacuspongida. VM Koltun. IN: Biological reports of the Soviet Antarctic Expedition, 1955-1958 (Rezultaty biologicheskikh issledovanii Sovetskoi antarkticheskoi ekspeditsii, 1955-1958). Volume 2. EP Pavlovskii, ed. Jerusalem : Israel Program for Scientific Translations. 1966. pp.6-131; Appendix, Index of Latin Names on pp. 443-448; 9: Instituto Antartico Chileno. Serie Cientifica 39:97-158, 1989; 10: Ross Sea Expeditions 1987-1988 and 1989-1990, Straits of Magellan Expedition 1991, Data Report Part 3, Physical, Chemical and Biological Oceanography. F Faranda and L Guglielmo, eds. Genova : Repubblica Italiana, Ministry of the University and Scientific and Technological Research, National Scientific Commision for Antarctica, 1994. pp.67-100; 11: Polar Biology 12:559-585, 1992; 12: Antarctic Science 9(4):3921-398, 1997; 13: Journal of Natural Products 61(1):116-118, 1998; 14: Biological Bulletin 198:29-33, 2000; 15: Ross Sea Ecology : Italiantartide Expeditions (1987-1995). FM Faranda, L Guglielmo, A Ianora, eds. Berlin : Springer, 2000. pp. 551- 561; 16: Systema Porifera. JNA Hooper and RWM Van Soest. New York: Kluwer, 2002

Text ©Peter Brueggeman. Photographs ©Jim Mastro, Rob Robbins, & Norbert Wu. Photographs may not be used in any form without the express written permission of Jim Mastro, Rob Robbins, & Norbert Wu. Norbert Wu no longer grants permission for uncompensated use of his photos under any circumstances whatsoever; want more info?