Food And Feeding

Until recently, krill have been considered to be exclusively herbivorous and, therefore, primary consumers in the ecosystem. Winter feeding and growth have been considered to be negligible since phytoplankton productivity decreases due to the extensive ice cover in the seas adjacent to the Antarctic. However, during 12 months of laboratory experiments with krill, carnivorous, detritivorous, and cannibalistic feeding were demonstrated (McWhinnie and Denys, 1978). Kott-meier and Sullivan (pers. comm.) have observed larval and juvenile krill feeding on the sea-ice microkrill community. This new knowledge of the occurrence of such feeding habits will require revision of established annual growth rate and, ultimately, longevity estimates of krill.

Experiments using a high-speed macro-photo-registration technique (Kils, 1983) suggest that krill are not limited to one feeding method, but employ a variety of highly efficient mechanisms. Depending on several factors such as food density, food quality, size of krill and, probably, activity level of the animal, different methods are employed by the animal to get the energy it needs.

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