Biofluorescence in Catsharks (Scyliorhinidae): Fundamental Description and Relevance for Elasmobranch Visual Ecology.
Biofluorescence has recently been found to be widespread in marine fishes, including sharks. Catsharks, such as the Swell Shark (Cephaloscyllium ventriosum) from the eastern Pacific and the Chain Catshark (Scyliorhinus retifer) from the western Atlantic, are known to exhibit bright green fluorescence. We examined the spectral sensitivity and visual characteristics of these reclusive sharks, while also considering the fluorescent properties of their skin. Spectral absorbance of the photoreceptor cells in these sharks revealed the presence of a single visual pigment in each species. Cephaloscyllium ventriosum exhibited a maximum absorbance of 484 ± 3 nm and an absorbance range at half maximum (λ1/2max) of 440-540 nm, whereas for S. retifer maximum absorbance was 488 ± 3 nm with the same absorbance range. Using the photoreceptor properties derived here, a "shark eye" camera was designed and developed that yielded contrast information on areas where fluorescence is anatomically distributed on the shark, as seen from other sharks' eyes of these two species. Phylogenetic investigations indicate that biofluorescence has evolved at least three times in cartilaginous fishes. The repeated evolution of biofluorescence in elasmobranchs, coupled with a visual adaptation to detect it; and evidence that biofluorescence creates greater luminosity contrast with the surrounding background, highlights the potential importance of biofluorescence in elasmobranch behavior and biology.
Baruch College, City University of New York, Department of Natural Sciences, New York, NY 10010, USA.|City University of New York, The Graduate Center, Program in Biology, New York, NY 10016, USA.|American Museum of Natural History, Sackler Institute for Comparative Genomics, New York, NY 10024, USA.
David F
DF
Gruber
College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Ellis R
ER
Loew
University of California, San Diego, Scripps Institution of Oceanography, La Jolla, CA 92093, USA.
Dimitri D
DD
Deheyn
University of Haifa, Charney School of Marine Sciences, Haifa, 3498838, Israel.|Interuniversity Institute of Marine Sciences, Eilat, 88103, Israel.
Derya
D
Akkaynak
Baruch College, City University of New York, Department of Natural Sciences, New York, NY 10010, USA.
Jean P
JP
Gaffney
University of Kansas, Biodiversity Institute and Department of Ecology and Evolutionary Biology, Lawrence, KS 66049, USA.
W Leo
WL
Smith
St. Cloud State University, Department of Biological Sciences, St. Cloud, MN 56301, USA.
Matthew P
MP
Davis
University of Kansas, Biodiversity Institute and Department of Ecology and Evolutionary Biology, Lawrence, KS 66049, USA.
Jennifer H
JH
Stern
The John B. Pierce Laboratory, Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06519, USA.
Vincent A
VA
Pieribone
American Museum of Natural History, Sackler Institute for Comparative Genomics, New York, NY 10024, USA.|American Museum of Natural History, Division of Vertebrate Zoology, Department of Ichthyology, New York, NY 10024, USA.
John S
JS
Sparks
D000221:Adaptation, Ocular; D000818:Animals; D001519:Behavior; D005075:Biological Evolution; D018940:Elasmobranchii / Q000502:physiology*; D005453:Fluorescence; D010786:Photoreceptor Cells / Q000502:physiology*; D010802:Phylogeny; D010860:Pigments, Biological / Q000737:chemistry / Q000378:metabolism*; D012754:Sharks / Q000502:physiology*; D012879:Skin Physiological Phenomena; D014785:Vision, Ocular
D010860:Pigments, Biological