An ocean of opsins

In this study, we explored the diversity and evolution of opsins using meta-omic data from the Tara Oceans and Tara Polar Circle expeditions, one of the largest marine datasets available. By using sequence similarity methods and phylogenetic analyses, we identified opsins across the different metazoan groups. Our results indicate that most of the opsin sequences belong to arthropods and vertebrates. We also detected sequences from all known opsin subfamilies, including r-opsin, c-opsin, xenopsin, and Group-4 opsins. Despite the broad taxonomic scope, no new opsin families were discovered; however, we provide valuable taxonomic insights into known opsin subfamilies and reinforce existing phylogenetic hypotheses. Additionally, we present novel opsin sequences from less-studied taxa, such as chaetognaths, rotifers, acoelomates, and tunicates, and which may serve as a valuable resource for future research into opsin function and diversity.