YU Ziniu and colleagues of CAS South China Sea Institute of Oceanology have completed the whole genome sequencing of Nautilus. Its genome is only 730.59 Mb and encodes 17,170 genes. Nautilus’s eyes lack a lens and use small hole imaging to adjust vision, forming a unique pinhole eye in nature, providing valuable materials and clues for exploring the evolution of the eye. Nautilus retains only the simplest optical signal transduction pathway and the only photosensitive molecule is r-opsin, indicating that it lacks the ability to distinguish colors. Nautilus is the only cephalopod with a shell. Scanning electron microscopy showed that the inner shell of nautilus was mainly composed of aragonite crystals (Aragonite). The shell protein identification results support the hypothesis that there is an ancient and conservative shell matrix protein “toolkit” in mollusks.

https://www.nature.com/articles/s41559-021-01448-6