Kitefin Shark’s Glow May Be a Sideways Searchlight, Not Just Camouflage
Eight live kitefin sharks show their bluish-green underside glow matches traditional counterillumination in color/brightness, but the emission also spreads sideways, especially from the nose and fins, potentially acting as a searchlight to illuminate prey on the seafloor. This dual-use - concealment plus prey attraction or signaling - challenges the idea that their bioluminescence is for camouflage alone, and suggests the light helps hunting in the deep sea. The study (iScience, 2026) analyzed bycatch sharks off New Zealand, with wild-behavior observations still needed to confirm how this works in nature.