Some species of deep-sea sharks have the ability to emit light. Lantern sharks are a family of sharks that does this.
Theories for the role of luminescence include species identification and camouflage in the dim light that reaches the deep-sea, however, proofs of the exact reason are still missing.

The BMAR research team from UCL (Louvain-la-Neuve - Belgium) and the Okinawa Churashima Foundation researched details of the dorsal luminescent patterns of three lantern shark species. We found groups of luminous organs around two dorsal spines, illuminating the spines. This suggests bioluminescence in these lantern sharks may aid in protecting itself from predators by displaying its spines (aposematism).

Dorsal bioluminescence pattern of two lantern shark species. Photo credit by Dr. Jérôme Mallefet

Authors

Laurent Duchatelet, Nicolas Pinte, Taketeru Tomita, Keiichi Sato, Jérôme Mallefet (Bold letters：Staff members of Okinawa Churashima Foundation)

Title of Paper

Etmopteridae bioluminescence: dorsal pattern specificity and aposematic use

Title of Journal

Zoological Letters

Article link

https://zoologicalletters.biomedcentral.com/articles/10.1186/s40851-019-0126-2