seastar Odontaster meridionalis

Odontaster meridionalis is found throughout Antarctica and the Antarctic Peninsula, South Shetland Islands, South Sandwich Islands, South Georgia Island, Straits of Magellan, Marion and Prince Edward Islands, Kerguelen Island, Shag Rocks, and Heard Island from zero to 647 meters depth [1,2,5,6,7,8,9,10]. O. meridionalis has a flattened disc with its arms narrowing down on the latter half of their length [8]. O. meridionalis has been collected at sizes up to nine centimeters in radius from its center to the tip of an arm [2]. O. meridionalis color is variable and includes yellow-white, dirty yellow, orange yellow, bright orange, pale brown, and a grey center grading to white at arm tips [2,7]. Here O. meridionalis is perched next to the featherduster worm Perkinsiana sp., probably Perkinsiana littoralis.



Odontaster meridionalis is an important predator of the sponge Homaxinella balfourensis and also eats the sponges Rossella racovitzae, Haliclona dancoi, Mycale (Oxymycale) acerata , Polymastia invaginata, Haliclona tenella, Isodictya setifera (shown here), and Pachychalina pedunculata [3,4].

Odontaster meridionalis is preyed upon by the anemone Urticinopsis antarcticus and the seastar Macroptychaster accrescens [5].



Female Odontaster meridionalis spawn their eggs by broadcasting them into the water where they develop into feeding larvae [1]. This differs from the more common tendency of McMurdo Sound seastars to have pelagic (open ocean) non-feeding larval development [1].

O. meridionalis is generally pale brown or yellowish white on the dorsal : surface and lighter on the ventral surface [11]. O. validus is usually bright to dull red on the dorsal (abactinal) surface and yellowish white to pale pink on the ventral (actinal) surface [11]. Color in both species can be highly variable and is not always reliable as a field character; the only sure way is to check the number of spines on the actinal plates [11].

1: Marine Biology 104:41-46, 1990; 2: The Fauna of the Ross Sea, Part 3, Asteroidea. HES Clark. New Zealand Department of Scientific and Industrial Research Bulletin 151, New Zealand Oceanographic Institute Memoir 21, 1963; 3: Science 245:1484-1486, 1989; 4: Ecological Monographs 44(1):105-128, 1974; 5: Adaptations within Antarctic Ecosystems : Proceedings of the Third SCAR Symposium on Antarctic Biology. George A. Llano, ed. Washington : Smithsonian Institution ; Houston, Tex. : distributed by Gulf Pub. Co., 1977. pp.293-326; 6: AM Clark. B.A.N.Z. Antarctic Research Expedition 1929-1931. Reports, Series B (Zoology and Botany) Volume 9, Asteroidea. Adelaide : BANZAR Expedition Committee, 1962; 7: Discovery Reports 20:69-306 and plates, 1940; 8: Equinodermos Antarticos. II. Asteroideos. 5. Asteroideos de la Extremidad Norte de la Peninsula Antartica. I Bernasconi. Revista del Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" e Instituto Nacional de Investigacion de las Ciencias Naturales. Zoologia (aka Ciencias Zoologicas) 9(10):211-281 and plates, 1970; 9: South African Journal of Antarctic Research 23(1-2):37- 70, 1993; 10: Scientia Marina 63(Supplement 1):433-438, 1999; 11: John Dearborn, personal communication, 2001

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