Lunch seminar with Laurent Duchatelet, postdoc at Kristineberg Marine Research Station, Department of Biological and Environmental Sciences
Laurent Duchatelet is currently part-time postdoc at Kristineberg, working together with Sam on multiple stressors impact on sea pen meadows. The rest of his time is spent at Université Catholique de Louvain in Belgium.
Short abstract
Marine fishes are the only vertebrates able to produce visible light. For more than two centuries, bioluminescence studies mainly focused on Osteichthyes, and a large amount of experimental data are available for these bony fishes. Conversely, luminescent sharks (11% of recognised shark species are luminous) were poorly investigated. Bioluminescent sharks are only found in Squaliformes, within the Etmopteridae, Dalatiidae and Somniosidae families. Since 2007, experimental studies on bioluminescent sharks have been conducted at the UCLouvain Marine Biology Laboratory (BMAR). Here, state-of-the-art insights on the evolution, ecological functions, histological structure, associated squamation and physiological control of the photogenic organs of these elusive deep-sea sharks are given. The data presented will summarise fifteen years of shark luminescence studies from species belonging to the three families (Etmopterus spinax, E. molleri, E. splendidus, E. lucifer, E. granulosus, Squaliolus aliae, Dalatias licha, and Zameus squamulosus), used to understand how, why, with which structures and where sharks are emitting light. Special focus is made on the unique and singular hormonal control of the light emission in sharks. In this context, the implication of photophore-associated extraocular photoreception - which complements the visual adaptations of bioluminescent sharks to perceive residual downwelling light and luminescence in dim light environment - in the hormonally-based bioluminescence control is depicted in details. Similarities and differences between families are highlighted and give weight to the hypothesis of a unique ancestral evolutive appearance of bioluminescence in elasmobranchs. Finally, potential areas for future research on shark bioluminescence will be presented.