Spectral tuning and signaling of diverse and far red-sensitive rhodopsins in mantis shrimp eyes.

Stomatopod crustaceans (mantis shrimps) have extraordinary eyes with unmatched visual rhodopsin diversity, but their potential for broad color detection remains unclear. Here, we report that 17 rhodopsins, mostly from the midband eye region, are involved in color sensing and functionally diverse signaling via Gq/Gi coupling and describe the underlying mechanisms of spectral tuning. Two mid-wavelength rhodopsins preferentially absorb blue light and a majority of long-wavelength opsins absorb in the green range, but three absorb light beyond 600 nanometers, representing exquisite far red-sensitive animal rhodopsins. Several blue and red rhodopsins exhibit photoreversibility with opposite spectral shifts explained by retinal binding interactions, revealing unrecognized photochemical flexibility in stomatopod photoreception. Row-specific spectral sensitivity results from combining carotenoid filters with multiple individually tuned rhodopsins, altogether extending broad vision to the far-red spectrum.