The ocean and its biodiversity have been attracting increasing interest from a humanities perspective over the last decades. The book Elusive Partners aims to provide a valuable insight into this research work on marine species, with a specific focus on the French-speaking world. Taking its inspiration from an interdisciplinary dialogue developed over several years at the National Museum of Natural History (Paris), this book highlights the need for comparative and long-term research on the most contemporary issues associated with marine species, particularly those related to conservation policies. Algae, cetaceans, seabirds, pinnipeds, turtles, corals and fish, but also more unexpected travellers —such as elephants or mice— compose a bestiary whose versatility and social, historical and political import are fully restored.