lamellarian gastropod Marseniopsis mollis

Marseniopsis mollis is found in Antarctica and the Antarctic Peninsula and South Shetland Islands at depths from 1 to 800 meters [3,4,5,6,8,10,11]. M. mollis ranges from 1.4 to seven centimeters long [3,4,5]. The mantle covering M. mollis is translucent lemon yellow and is soft, smooth, rounded, thick, and fleshy [4,7]. M. mollis is the most common species in the genus Marseniopsis in Antarctica [3].

The tail of Marseniopsis mollis projects slightly but is not visible from top view [7].

M. mollis does not have a shell for protection from predators, though it does have a thin, fragile, transparent, internal shell, which has two to three complete whorls [3,7,11].

M. mollis has been found in the stomach contents of the fish Trematomus hansoni [9].


Here's the head of Marseniopsis mollis looking at its foot from the underside.

M. mollis appears to be protected from predation by a chemical, homarine, which deters feeding [1,2].

Marseniopsis mollis is the primary predator of the tunicate Cnemidocarpa verrucosa, on which it is crawling in this photo [1]. M. mollis appears to obtain its defensive chemical homarine from bryozoans and hydroids growing on the surface of the tunicate Cnemidocarpa verrucosa [1,2].

1: Antarctic Journal of the United States 29(5):151-153, 1994; 2: Journal of Chemical Ecology 20(10):2539- 2549, 1994; 3: Proceedings of the NIPR Symposium on Polar Biology 4:50- 68, 1991 (National Institute of Polar Research, Tokyo); 4: Tethys Supplement 4:105-134, 1972; 5: Antarctic Mollusca : with Special Reference to the Fauna of the Ross Sea. RK Dell. Wellington, NZ : Royal Society of New Zealand, 1990. Bulletin 27, Royal Society of New Zealand; 6: Records of the Auckland Institute and Museum 5(3,4):117-193, 1960; 7: British Antarctic "Terra Nova" Expedition, 1910. Natural History Reports: Zoology. Volume 7. Mollusca. Polychaeta. Chaetognatha. London : Trustees of the British Museum, 1923; 8: Polish Polar Research 7(1-2):25-62, 1986; 9: Bulletin de l'Institut Oceanographique 66(1368), 1966; 10: Polar Biology 20(4):229-247, 1998; 11: Taxonomic Study on Antarctic Gastropods Collected by Japanese Antarctic Research Expeditions. H Numanami. Memoirs of National Institute of Polar Research, Series E (Biology and Medical Science), Number 39. Tokyo : National Institute of Polar Research, 1996

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