The polar pteropod Clione limacina is characterised by high quantities of lipids with ether components (1-O-alkyldiacylglycerol=DAGE) in combination with odd-chain fatty acids. It is unknown why Clione and probably other pteropods have specialised in this manner. Furthermore the precursor of the biosynthesis of these compounds is still unknown. Therefore samples of Clione limacina and its only prey Limacina helicina will be collected by using plankton nets from small boats. The species will be kept in aquaria and feeding experiments with both species and food of different composition and nutritional value are planed.