Antarctic and Arctic zooplankton species have developed very similar life strategies and energetic adaptations to the harsh environment via sophisticated modes of lipid accumulation. A very efficient biosynthesis, storage and utilization of lipids enable especially herbivorous species to buffer the pronounced seasonality of food supply in the polar oceans. Lipid levels usually peak at the end of the productive season in autumn and reach minimum levels in spring. In many species lipid deposits are not primarily used for maintenance during winter but are conserved to fuel reproductive processes at the end of the dark season. The dependence on seasonal primary production is also reflected by the respective lipid compositions. Detailed lipid analyses of dominant Antarctic and Arctic copepods revealed that the herbivorous Calanus and Calanoides species have developed the most complex lipid biochemical pathways. They biosynthesise large amounts of wax esters with long-chain monounsaturated fatty acids and alcohols (20:1, 22:1) as major components. In contrast, the Antarctic Calanus propinquus and C. simillimus synthesise primarily triacylglycerols consisting mainly of long-chain monounsaturated fatty acids with 22 and even 24 carbon atoms (2 major isomers), which is very unusual among plankton species. In contrast, the lipids of omnivorous and carnivorous taxa such as Metridia or Euchaeta are deficient in such long-chain fatty acids and alcohols, although their lipid reserves mainly consist of wax esters. Our investigations underscore that lipids are a key factor in high latitude ecosystems, especially for the lower trophic levels. The extremely lipid-rich herbivorous species ensure an efficient lipid-based energy transfer and represent high-calory food for fish and warm-blooded animals like birds and mammals.