The lantern shark's light switch: turning shallow water crypsis into midwater camouflage.

The article discusses a study that examined the intrinsic photophores of the lantern shark, Etmopterus spinax. Photophore-containing skin patches from the sharks were excised. The study showed that hormones operate what amounts to a unique light switch, by acting on a chromatophore iris. It suggests that the luminescence control of the shark originates from the mechanism for physiological colour change found in shallow water sharks.