The Covert World of Fish Biofluorescence: A Phylogenetically Widespread and Phenotypically Variable Phenomenon

Abstract

The discovery of fluorescent proteins has revolutionized experimental biology. Whereas the majority of fluorescent proteins have been identified from cnidarians, recently several fluorescent proteins have been isolated across the animal tree of life. Here we show that biofluorescence is not only phylogenetically widespread, but is also phenotypically variable across both cartilaginous and bony fishes, highlighting its evolutionary history and the possibility for discovery of numerous novel fluorescent proteins. Fish biofluorescence is especially common and morphologically variable in cryptically patterned coral-reef lineages. We identified 16 orders, 50 families, 105 genera, and more than 180 species of biofluorescent fishes. We have also reconstructed our current understanding of the phylogenetic distribution of biofluorescence for ray-finned fishes. The presence of yellow long-pass intraocular filters in many biofluorescent fish lineages and the substantive color vision capabilities of coral-reef fishes suggest that they are capable of detecting fluoresced light. We present species-specific emission patterns among closely related species, indicating that biofluorescence potentially functions in intraspecific communication and evidence that fluorescence can be used for camouflage. This research provides insight into the distribution, evolution, and phenotypic variability of biofluorescence in marine lineages and examines the role this variation may play.

Method for Determining the Contribution of Fluorescence to an Optical Signature, with Implications for Postulating a Visual Function

“…Much of this has focused on origin and possible ecophysiological roles of the fluorescing proteins in reef corals (Salih et al, 2000;Kelmanson and Matz, 2003;Ugalde et al, 2004;Bou-Abdallah et al, 2006;Palmer et al, 2009;Gittins et al, 2015;Smith et al, 2017), but some studies have touched on possible visual functions in fish and other marine organisms (Mazel et al, 2004;Haddock et al, 2005;Matz et al, 2006;Michiels et al, 2008;Gerlach et al, 2014;Sparks et al, 2014;Haddock and Dunn, 2015;Gruber et al, 2016). A few of these latter have had a strong foundation in measurement and analysis, while others have been more speculative and suggestive, based purely on observation and correlation.…”

“…There have been peer-reviewed publications that have strongly suggested, or even claimed, demonstration of a visual function based simply on criteria 1, or 1 and 2, combined with a hypothesis (untested) about the role the fluorescence might play in the organism's life (Sparks et al, 2014;Gruber et al, 2016). This is not sufficient.…”

First record of albinism in the swell shark, Cephaloscyllium ventriosum (Elasmobranchii: Carcharhiniformes: Scyliorhinidae)

“…Because its visual acuity and ability to see bioluminescence would not depend mainly on melanin (Wang et al 2007, Sparks et al 2014, Gruber et al 2016, social interactions with other swell sharks would be possible as well, as was previously suggested for albino elasmobranchs with yellow-orange eyes, caught either in interspecific aggregations (De JesusRoldan 1990) or swimming alone, but with apparently healthy status (Clark 2002, Sandoval-Castillo et al 2006, Reum et al 2008, Lipej et al 2011, Bigman et al 2015, Wakida-Kusunoki 2015. The specimen of Cephaloscyllium ventriosum presented here was considered a mature female, according to Ramírez-Amaro et al (2013).…”

Stars and stripes: biofluorescent lures in the striated frogfish indicate role in aggressive mimicry

“…Recent research shows biofluorescence is common in cryptic-patterned coral reef fishes (Sparks et al 2014). The functional roles of biofluorescence are largely unknown although camouflage and covert intraspecific communication have been hypothesized (Sparks et al 2014).…”

“…The functional roles of biofluorescence are largely unknown although camouflage and covert intraspecific communication have been hypothesized (Sparks et al 2014).…”