Comparative control of luminescence in sharks: New insights from the slendertail lanternshark (Etmopterus molleri)

• We investigated the bioluminescence of the lanternshark Etmopterus molleri.
• This shark has a complex, potentially versatile pattern of photogenic organs.
• Photogenic organs are always activated by melatonin but rarely by prolactin.
• Nitric oxide potentiates melatonin-induced luminescence.
• These results provide new insights in the evolution of shark luminescence.

Here, we investigated the organisation and physiological control of photophores from the slendertail lanternshark (Etmopterus molleri), an etmopterid species phylogenetically distant from E. spinax, one of the two current model species for shark photophore control study. Our results support the idea that lanternsharks evolved a common photophore control mechanism, more complex compared to that of dalatiid sharks, in order to use their luminescence as a versatile deep-sea tool.