sponge Suberites sp.

One of the Suberites species found in McMurdo Sound is the yellow ball sponge Suberites montiniger, found throughout Antarctica and the Falkland Islands, the North Pacific Ocean, the North Atlantic Ocean, and the Arctic Ocean from 24 to 700 meters depth [1,2,3]. The body of S. montiniger is hard and rounded, spherical or ball-shaped, and up to ten centimeters high [2]. The surface of S. montiniger is smooth and may have low papillae with cratered openings [2]. The color of S. montiniger is yellowish orange or brown on the outside and yellowish on the inside [2].

Another photo of Suberites sp. sponge, to the left of Sphaerotylus antarcticus.

Diatoms, particularly of the genera Achnanthes and Porosira, have been found living in the tissue of Suberites montiniger [4]. Found within the food-capturing cells lining the passages through which the sponge circulates water, these endobiont diatoms live by consuming carbohydrates produced by the sponge and also by photosynthesis [5]. Diatoms produce large amounts of polysaccharids, thus giving the sponge an alternative food source during food-scarce periods [4]. 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) [5].

1: Hooper, JNA & Wiedenmayer, F. Porifera. IN: Zoological Catalogue of Australia. Volume 12. Wells, A, ed. Melbourne : CSIRO Australia, 1994; 2: 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; 3: Polar Biology 12:559- 585, 1992; 4: Ross Sea Ecology : Italiantartide Expeditions (1987-1995). FM Faranda, L Guglielmo, A Ianora, eds. Berlin : Springer, 2000. pp. 551- 561; 5: Biological Bulletin 198:29-33, 2000

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