scyphomedusa Diplulmaris antarctica

Diplulmaris antarctica is found in Antarctica and the Antarctic Peninsula near the surface in continental shelf waters [1]. D. antarctica has 16 - 48 whitish laterally compressed tentacles [1].


Diplulmaris antarctica has frilled curtain-like reddish-orange oral arms and its stomach gastrodermis is also reddish-orange [1].


The colorless bell-like umbrella of Diplulmaris antarctica can be up to eighteen centimeters in diameter [1,2].

D. antarctica feeds on copepods, euphausiid larvae, medusae, ctenophores, fish larvae, and the molluscan pteropods Clione antarctica and Limacina helicina [1,2].

Diplulmaris antarctica is usually infested with a hyperiid amphipod Hyperiella dilatata which sits with its dorsal (top) surface against the outside top of the medusa's bell, the exumbrellar surface [2]. The hyperiid amphipods are those white dots on the surface of the clear bell in the picture at left. Collectors have found up to 54 of these hyperiid amphipods riding along, clinging tightly to the medusa. These riding amphipods are predominantly juveniles and females; this suggests that the medusa is both an amphipod mating platform (where females await more mobile males) and a predation refuge for juveniles and females [2]. The hyperiid amphipods do not appear to feed on the medusa and probably use it as a safe harbor between feeding forays [2]. Diplulmaris antarctica has also been reported in association with the hyperiid amphipod Hyperia macrocephala [1].

Diplulmaris antarctica which get close enough to the bottom in shallow water are prey to be captured by the tentacles of an anemone (Isotealia antarctica shown here) [3]. The struggle can continue for quite awhile. The medusa pulses its bell as it tries to swim away while the anemone slowly pulls the medusa into its mouth. The hitchhiking amphipods are going to get consumed by the anemone too.

Gelatinous carnivores are a predominant and sometimes the main component of the macroplankton and nekton community in the Southern Ocean [4]. Gelatinous carnivores are important components of the food web because they are a control mechanism for its structure [5].

1: Pelagic Scyphomedusae (Scyphozoa: Coronatae and Semaeostomeae) of the Southern Ocean. RJ Larson. Washington, DC: American Geophysical Union, 1986; 2: Polar Biology 11(1):19-25, 1990; 3: Antarctic Ecology, Volume 1. MW Holdgate, ed. NY: Academic Press, 1970. pp244-258; 4: Annales de l'Institut Oceanographique 73(2):139-158, 1997; 5: Annales de l'Institut Oceanographique 73(2):123-124, 1997

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