ice krill Euphausia crystallorophias

Euphausia crystallorophias is found throughout Antarctica and the Antarctic Peninsula from the surface down to usually 300 to 650 meters depth and has been recorded near 4,000 meters depth [1,5]. E. crystallorophias reaches a maximum length of 3.4 centimeters, with females slightly larger than males [1,2,5]. E. crystallorophias is a swarming species and an important food source for coastal predators, eaten by whales and other large animals (Minke whales, Weddell seals, Adelie penguins, fish particularly Pleuragramma antarcticum) [1,4,5,6]. E. crystallorophias replaces E. superba in dominance in regions of pack and floating ice and the pelagic shelf community [1,4,5,6]. E. crystallorophias may be the major single pelagic consumer of phytoplankton on the Antarctic shelf [4]. E. crystallorophias undertakes a vertical diel migration and breeds from the end of December to February under the ice [1]. Coastal polynas are areas of enhanced spawning and grazing for E. crystallorophias [4].

E. crystallorophias was first described from specimens collected through holes cut in the ice by Scott's Discovery Expedtion [3].

Euphausiids are small translucent shrimp-like crustaceans commonly known as krill; seven species belonging to two genera Euphausia and Thysanoessa occur in the Southern Ocean [1,2]. The genus name Euphausia refers to the luminescence produced by large light organs (photophores) [2]. An Antarctic midwater trawling fishery based on Euphausia superba catches krill for human and domentic animal consuption [1]. E. crystallorophias is similar to E. superba but has a longer rostrum, larger eyes, a shorter mandibular palp, and is shorter in overall length [5].

1: FAO Species Identification Sheets for Fishery Purposes : Southern Ocean (Fishing Areas 48, 58 and 88) (CCAMLR Convention Area) / W Fischer & JC Hureau, eds. Rome : Food and Agriculture Organization of the United Nations, 1985; 2: A Practical Guide to the Euphausiids of the World. A de C Baker, BP Boden & E Brinton. London : Natural History Museum Publications, 1990; 3: Annals and Magazine of Natural History 17(Seventh Series):1-11, 1906; 4: Antarctic Communities: Species, Structure, and Survival. B Battaglia, J Valencia, and DWH Walton, eds. Cambridge: Cambridge University Press, 1997; 5: A Guide to the Euphausiacea of the Southern Ocean. JM Kirkwood. ANARE Research Notes 1 (Australian National Antarctic Research Expedition). Kingston, Tasmania, Australia: Australia Dept of Science and Technology, Antarctic Division, 1984; 6: Polar Biology 8(5):327-331, 1988

Text ©Peter Brueggeman. Photograph ©Steve Alexander. Photographs may not be used in any form without the express written permission of Steve Alexander.