dendronotid nudibranch Tritoniella belli

Tritoniella belli is found in Antarctica and the Antarctic Peninsula, South Shetland Islands, South Orkney Islands, South Georgia Island, Shag Rock, and Kerguelen Island at depths from 7 to 699 meters [1,6,7,8,9]. T. belli has a longitudinal ridge along its back and can be up to eight centimeters in length [1].

T. belli can have two morphological types: (1) tubercle-covered body with a yellow to orange color and a ridged margin; found predominately along the Antarctic Peninsula; (2) milky-white to transparent body with few tubercles and a serrated margin sometimes with small finger-shaped processes; prevails in the Weddell Sea and Signy Island (South Orkney Islands) [1]. Both morphs can be found elsewhere in Antarctica [1].

One study found Tritoniella belli primarily on bare rock surfaces or upon the hydroid Ophiodes arboreus, with smaller numbers of T. belli found on the bush sponge Homaxinella balfourensis and the soft corals Alcyonium antarcticum and Clavularia frankliniana [7]. This suggests that T. belli is feeding on these organisms and also on growth on rock surfaces; gut contents include benthic diatoms [7]. Another study noted that T. belli feeds primarily on the stoloniferan soft coral Clavularia frankliniana, occasionally eats hydroids and anemones, and probably eats tunicates on which its eggs can be found [2,3,5]. T. belli has been observed feeding on the octocoral Ascolepis sp [6].


Egg ribbons of Tritoniella belli have been observed on bare rock surfaces, on the hydroid Ophiodes arboreus, and on the bush sponge Homaxinella balfourensis [7].

Here Tritoniella belli is crawling across the predatory seastar Odontaster validus. Extracts of T. belli and the soft coral Clavularia frankliniana have chimyl alcohol in common. O. validus shows feeding deterrence to T. belli mantle tissue and to chimyl alcohol [3]. T. belli probably defends itself chemically against predators using chimyl alcohol that it obtains from the soft coral Clavularia frankliniana. T. belli mantle tissue is also noxious to the sea urchin Sterechinus neumayeri, several other seastars and two species of fish [4].

1: Polar Biology 9(4):235-243, 1989; 2: Ecological Monographs 44(1):105-128, 1974; 3: Journal of Chemical Ecology  20(12):3361-3372, 1994; 4: Polar Biology 11(8):623-629, 1992; 5: Marine Biology 100(4):439-441, 1989; 6: Journal of Molluscan Studies 62(3):281-287, 1996; 7: Marine Biology 132:259-265, 1998; 8: Tethys 6(3):631-653, 1974; 9: Polar Biology 24(2):105-112, 2001

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