“Which species are there?”, “Where are they in the water column and why?”, “Who eats whom?” – These and other seemingly simple questions remain largely unanswered for the deep sea, the largest and least explored habitat for life on Earth. At the same time, climate change and increasing human exploitation are putting pressure on this unique system. In this situation, better scientific information to answer the “simple questions” and thus a better understanding of ecosystem functioning is of fundamental scientific interest, but also highly relevant to guide conservation efforts.

On 9 February, our cruise MSM126 “Jellyweb” Madeira left the port of Funchal, Madeira, Portugal, with 22 scientists from seven institutes in five nations and 24 permanent crew on board. Our mission: to improve the understanding of the biodiversity and food web structure of the deep-sea systems around Madeira down to depths of 3000 m. We are particularly interested in the role of gelatinous species such as jellyfish, hydromedusae, salps or chaetognaths (the “jelly web”), which can occur in high diversity and biomass, but are rarely caught intact in nets due to their fragile bodies and have therefore often been neglected in marine research.

A salp (Soestia zonaria), part of the gelatinous fauna in which we are particularly interested. Photo: Karen Osborn

Until the end of our cruise on 4 March in Las Palmas, Gran Canaria, we want to introduce you to our scientific questions, the equipment and approaches we use to address them, and share impressions of the deep sea and its amazing inhabitants.

Ultimately, we hope to convey some of the magic of the unique deep-sea world that we are privileged to witness every day on this cruise – a wonder worth sharing, worth our scientific attention and, above all, worth protecting.

All the best from aboard the research vessel MARIA S. MERIAN,

Jan (Chief Scientist MSM126, on behalf of all participants)