Gelatinous zooplankton or “jellies” (ctenophores, cnidarians, tunicates) are known to be major drivers of ecosystem changes. Increases in jelly biomass, referred to as “jellification”, have been observed in several marine ecosystems, causing, amongst others, the collapse of major fisheries. For the Arctic region, abundance data on jellies are virtually non-existent, impeding our ability to detect changes of a similar magnitude. To better understand the role of jellies in the Arctic seas, the Helmholtz Young Investigator Group ARJEL (2019-2026), aims to combine the most recent technologies in optics, acoustics, and environmental DNA analyses. Based on data collected during recent international campaigns, we attempt to link distributional patterns of jellies to sea-ice and oceanographic features. Furthermore, we apply species distribution models to a broad set of archived data to understand observed species and community patterns and to predict changes under future climate-change scenarios. The role of jellies in the Arctic food web, their importance for planktonic predators and fish and their link to the sea-ice trophic pathway is assessed with molecular diet studies. Physiological and transcriptomic studies serve to predict range expansions, and the consequences of expansion will be predicted based on food web models. An overview of the project’s goals, methods and first results will be given. One of our first research highlights include the comparison of species composition and abundances of ctenophores and cnidarians in Arctic vs. Atlantic-influenced Svalbard fjords. We also demonstrate a seasonality in species composition of the gelatinous component of the zooplankton observed during the year-long expedition MOSAiC in the central-Arctic.