Galaxea, Journal of Coral Reef Studies 21: 7-8（2019）
Photogallery
Fluorescence emission in a marine snake
Takashi SEIKO and Yohey TERAI
SOKENDAI (The Graduate University for Advanced Studies), Department of Evolutionary Studies of Biosystems, Shonan Village, Hayama, Kanagawa 240-0193, Japan.
Corresponding authors: Y. Terai, T. Seiko E-mails: [email protected]; [email protected]
Communicated by Frederic Sinniger (Associate Editors-in-Chief)
Keywords fluorescence,Laticauda , marine reptile, sea krait
Coral reefs are one of the most colorful environments on Earth. Light in coral reefs includes fluorescence as well as reflectance of sunlight. In fluorescence, mole cules are excited by illuminating light and emit longer wavelength fluorescence than the excitation light wave length. In coral reefs, fluorescent light emission is observed in a range of taxa including cnidarians (e.g. corals), arthropods and fishes (e.g., Johnsen 2012). In marine reptiles, fluorescent emission has reported thus far only from sea turtles (Gruber and Sparks 2015). Here we report fluorescent light emission in a marine snake. Laticauda laticaudata Linnaeus, 1758 is a semi aquatic sea krait (Elapidae: Laticaudinae) often ob served in coral reefs. We examined a specimen that was freshly frozen after death and subsequently thawed. This specimen was caught at Ogan-zaki, Ishigaki- island, Okinawa, Japan (24°27′12.4″N; 124°04′37.4″E)
Fig. 1 Photographs of a sea krait (Laticauda laticaudata) illuminated with white light (A) without a filter, and ultraviolet LED light (B) through a blue light cutting filter (<490 nm). (C) A reflectance and fluorescence light spectrum measured from a pale band. Reflectance of excitation light and fluo rescence are shown in blue and green, respectively. 8 Seiko and Terai: Fluorescence emission in a marine snake and euthanased by anaesthetic injection for another study in University of the Ryukyus, and subsequently transferred to SOKENDAI for fluorescent analysis. Compared with a photograph taken under white light (Fig. 1A), the skin of the sea krait under illumination with ultraviolet LED light (peak at 370 nm) was bright through a blue light (<490 nm) cutting filter (Y49, Asahi-techno inc., Tokyo Japan) (Fig. 1B). The skin emitted longer wavelength (<490 nm) light than the ultraviolet light illumination, indicating fluorescent emission. We measured light emission, including reflectance and fluorescence, from a white band of skin with the ultraviolet LED light as an excitation light using a Jaz Spectrometer (Ocean Optics, Dunedin, FL, USA). The spectrum shows reflectance of an excitation light and clear fluorescence with a peak at 514 nm (Fig. 1C). Fluorescence has been reported in other snakes but only rarely and in few taxa (e.g., the burrowing, terrestrial scolecophidian Rena humilis (Baird & Girard, 1853) (Hulse 1971). Although fluorescence in snakes is very understudied, a fluorescent substance has previously been reported in the skin of three colubrid and one viperid terrestrial snake species (Odate et al.1959), and this or similar substances might be sought also in L. laticaudata.
Acknowledgments We thank Mr. T Sasai, Drs. T Kishida and M Toda for a sea krait specimen and helpful advice. This work was supported by Grant-in-Aid for JSPS Research Fellow Grant Number 18J15154 to T. S. We are grateful to Dr. W. Wüster, Dr. D. Gower, and a third anonymous reviewer for their constructive critical reviews.
Compliance The animal protocols and procedures were approved by the Animal Care and Use Committee of SOKENDAI (permission number SKD2017AR002).
References Johnsen S (2012) The optics of life: a biologist’s guide to light in nature. Princeton University Press, New Jersey. p 191 Gruber DF, Sparks JS (2015) First observation of fluorescence in marine turtles. Am Mus Novit 3845: -1 8 Odate S, Tatebe Y, Obika M, Hama T (1959) Pteridine derivatives in reptilian skin. Proc Jpn Acad 35: 567-570 Hulse AC (1971) Fluoresence in Leptotyphlops humilis (Serpentes: Leptotyphlopidae). Southwest Nat 16: 123-124
Received: 8 January 2019/Accepted: 18 June 2019 Ⓒ Japanese Coral Reef Society