This manuscript presents an investigation of receptors in the trunk of Platynereis annelids that express genes involved in both photoreception (e.g. r-Opsin) and mechanosensation. This is particularly interesting in light of other work in model organisms like flies that uncovered broadly similar results. The authors compare gene expression of fly Johnston Organ cells and mouse hearing cells to the worm receptors. Because Platynereis is distantly related to flies and mice, the authors suggest this "hybrid" sensory receptor could be very old and homologous across many animals. The question of what role r-Opsins play outside of photoreceptors is an interesting one that remains poorly understood.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 and Reviewer #4 agreed to share their names with the authors.)