Dynamic blinking in the head of hardyhead silverside fish

Abstract

Abstract Dynamic light reflection can be used to provide an efficient tool for biological sensing of micro and nano-organisms. It is therefore interesting that evidence of dynamic light reflection can also be found in the animal kingdom and that there may be alternative methods of light control actuation. In this study, it is discovered that several features in the heads of hardyhead silverside fish, particularly those located around the edges of the iris, caused a blinking phenomenon using environmentally scattered light. Analysis of the blinking using recorded video of the fish iris revealed that circular cells that exist in the iris changed their light intensity at approximately 2 Hz. These cells, which are 5–10 μm in diameter, are normally blue. However, it is found that a distinct light intensity changed in 0.04 s, and additional green and yellow colors then overlapped with the blue.