Mid-Infrared Free-Electron Laser-Evoked Discharge of Crayfish Compound Eyes

Abstract

Infrared radiation at short wavelengths, in particular near- and mid-infrared, are valuable probes for investigating mutual reactions between light and molecules in living organisms. However, it remains controversial as to whether animals can see mid-infrared (3.30 μm) radiation. To investigate the ability of crayfish (Procambarus clarkii) compound eyes to detect mid-infrared radiation, we used a free-electron laser (FEL) as a light source. We found that the crayfish compound eye can respond to pulsed mid-infrared (3.17 μm) radiation from the FEL, which may be a novel mid-infrared response in the animals visual organ. These findings present positive evidence to resolve the long-running question about whether the vision organs in P. clarkii are responsive to mid-infrared radiation. This study opens new avenues of research, such as investigating how and when crayfish uses electrical signals evoked by mid-infrared radiation in their behavior.