probably lamellarian gastropod Marseniopsis syowaensis

Marseniopsis syowaensis is found in Antarctica from 5 to 49 meters depth [1,2,3,4]. M. syowaensis is very large compared to other Antarctic lamellariids, up to 11.5 centimeters long [1,3]. The mantle of M. syowaensis can be dome-like in shape, with numerous wrinkles and irregular warts of shrinkage, feeling soft and jelly-like but very thick [1,3]. The mantle of M. syowaensis is colored pale pink with pale brown spots; its ventral underside is only pale pink, and its foot and head tentacles are white [1,3].

This photo of Marseniopsis syowaensis was taken at New Harbor at 33 meters depth; it was observed that the mantle surface felt almost smooth but a little bumpy [2].


Shown here are egg masses laid by a Marseniopsis spp. on a scallop at New Harbor, and a seastar (possibly Pteraster affinis aculeatus) eating them, and probably the scallop too [4].

Lamellarian species feed on ascidians and sponges [3]. A Weddell seal was observed feeding on M. syowaensis, and the large size of this mollusc may make it a good food resource for the Weddell seal [3]. The species name commerates the Japanese Antarctic Research Expedition's research station Syowa [3].

1: 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; 2: Jim Mastro, personal communication, 1999; 3: Proceedings of the NIPR Symposium on Polar Biology 4: 50-68, 1991; 4: Paul Dayton, personal communication, 2003 (found one at 160 ft at New Harbor)

Text ©Peter Brueggeman. Photograph ©Jim Mastro & Rob Robbins. Photographs may not be used in any form without the express written permission of Jim Mastro & Rob Robbins.