Our knowledge on polar night ecology is poor. Most Arctic studies are conducted during the light season from spring to autumn when field work is convenient. The dark Arctic winter, however, may last up to eight or nine months depending on the snow depth a nd sea ice cover. The ecological and physiological processes during this extended time period are likely critical for the condition of polar organisms in the following spring. Therefore, if we are to elucidate climate change impacts on Arctic marine syste ms, more knowledge on polar night ecology and processes is therefore crucial. New observations strongly suggest that Arctic marine organisms do not shut down their activity during the dark and food-poor winter as previously assumed (Berge et al. 2009). A continued activity of zooplankton species migrating in the water column throughout the polar night period also influences the biogeochemical cycling of carbon. New tools are needed to be able to study these polar night biological processes. In this projec t, leading Norwegian and American scientist will closely cooperate to establish new innovative molecular methods and physiological measurements to study feeding activity and metabolism of key Arctic organisms at the base of the marine food web during the so far big black box of polar night ecological processes.