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Dryad

Putative photosensitivity in internal light organs (organs of Pesta) of deep-sea sergestid shrimps

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Feb 22, 2024 version files 115.49 MB

Abstract

Many marine species can regulate the intensity of bioluminescence from their ventral photophores in order to counterilluminate, a camouflage technique whereby animals closely match the intensity of the downwelling illumination blocked by their bodies, thereby hiding their silhouettes. Recent studies on autogenic cuticular photophores in deep-sea shrimps indicate that the photophores themselves are light-sensitive. Here, our results further suggest photosensitivity in a second type of autogenic photophore, the internal organs of Pesta, found in deep-sea sergestid shrimps. Experiments were conducted ship-board on live specimens, exposing the animals to bright light, which resulted in ultrastructural changes that matched those seen in crustacean eyes during the photoreceptor membrane turnover, a process that is crucial for the proper functioning of photosensitive components. In addition, RNA-seq studies demonstrated the expression of visual opsins and phototransduction genes in organs of Pesta tissue that are known to play a role in light detection, and electrophysiological measurements indicated that the light organs are responding to light received by the eyes. The long-sought-after mechanism of counterillumination remains unknown, but evidence of photosensitivity in photophores may indicate a dual functionality of light detection and emission.