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


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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.
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The Covert World of Fish Biofluorescence: A
Phylogenetically Widespread and Phenotypically
Variable Phenomenon
John S. Sparks
, Robert C. Schelly
, W. Leo Smith
, Matthew P. Davis
, Dan Tchernov
Vincent A. Pieribone
, David F. Gruber
1Department of Ichthyology, American Museum of Natural History, Division of Vertebrate Zoology, New York, New York United States of America, 2Sackler Institute for
Comparative Genomics, American Museum of Natural History, New York, New York, United States of America, 3Biodiversity Institute, University of Kansas, Lawrence,
Kansas, United States of America, 4Marine Biology Department, The Leon H. Charney School of Marine Sciences, University of Haifa, Mount Carmel, Haifa, Israel,
5Department of Cellular and Molecular Physiology, The John B. Pierce Laboratory, Inc., Yale University, New Haven, Connecticut, United States of America, 6Department
of Natural Sciences, Baruch College, City University of New York, New York, New York, United States of America
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.
Citation: Sparks JS, Schelly RC, Smith WL, Davis MP, Tchernov D, et al. (2014) The Covert World of Fish Biofluorescence: A Phylogenetically Widespread and
Phenotypically Variable Phenomenon. PLoS ONE 9(1): e83259. doi:10.1371/journal.pone.0083259
Editor: Diego Fontaneto, Consiglio Nazionale delle Ricerche (CNR), Italy
Received September 28, 2013; Accepted October 31, 2013; Published January 8, 2014
Copyright: ß2014 Sparks et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was supported by the American Museum of Natural History, City University of New York, National Science Foundation grants DEB-0444842,
IOS-0749943, and DEB-1258141 to JSS, MCB-0920572 and DRL-1007747 to DFG, DEB-0732642 and DEB-1060869 to WLS, DEB-1257555 and DEB-1258141 to MPD,
WLS, and JSS, National Institutes of Health (NIH) grants U24NS057631 and R01NS083875 to VAP and National Geographic Waitt Grants #W101-10 to DFG and
#W214-12 to JSS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: (JSS); (DFG)
.These authors contributed equally to this work.
The primarily monochromatic blue spectrum that characterizes
large areas of the photic ocean provides a unique filtered-light
environment for visual organisms. Compared to the terrestrial
environment, marine organisms reside in a spectrally restricted
visual domain. The red, orange, yellow, and green components of
sunlight are selectively removed with depth resulting in a narrow,
near-monochromatic, band of blue light between 470 and 480 nm
[1]. Spectrally restricted illumination in the ocean provides unique
lighting conditions for organisms to exploit fluorescence to
produce visual contrast and patterns. In the marine environment,
biofluorescence is highly prevalent in cnidarians (particularly
Anthozoans) [2], and also in a ctenophore [3], copepods [4],
mantis shrimp [5], amphioxus [6] and some fishes [7]. In addition,
the photosynthetic apparatus associated with chlorophyll fluoresc-
es red and provides a background of biofluorescence in areas of
high algal growth on coral reefs.
Biofluorescence results from the absorption of electromagnetic
radiation at one wavelength by an organism, followed by its
reemission at a longer and lower energy wavelength, visually
resulting in green, orange, and red emission coloration in marine
organisms. Biofluorescence signaling has previously been reported
in butterflies [7], parrots [9], spiders [10], and flowers [11], as well
as a deep-sea siphonophore [12]. In scleractinian corals, biofluor-
escence has been suggested to function in photoprotection [13],
antioxidation [14], regulation of symbiotic dinoflagellates [15],
photoacclimation [16], visual contrast [2], and coral health [17].
Whereas insight into the evolution and function of biofluores-
cence has greatly enhanced our knowledge of coral biology, little
to nothing is known regarding the impact of biofluorescence on
other organisms that thrive in coral-reef habitats, particularly
those with advanced visual systems that could readily exploit
fluorescent coloration and contrast. Investigating the evolution of
biofluorescence across marine fishes is particularly appealing
PLOS ONE | 1 January 2014 | Volume 9 | Issue 1 | e83259
because they are visual animals, many of which possess yellow
intraocular (lenses or cornea) filters [18], which function as long-
pass filters and could enable enhanced perception of biofluores-
cence in the ocean. Worldwide, there are more than 8,000 species
of fishes that inhabit coral reefs. Many reef fish species are known
for their striking color patterns, whereas many others are
cryptically patterned and appear well camouflaged. However,
nearly nothing is known regarding the evolution or function of
fluorescence in fishes. Only recently has a fluorescent protein, a
novel fatty-acid-binding protein, been isolated from a vertebrate, a
Japanese eel [19].
Here we report, for the first time, that biofluorescence is
widespread throughout the tree of life for fishes, and it appears
particularly common and phenotypically variable in marine
lineages, especially cryptically patterned, well camouflaged coral-
reef lineages. Our findings identify a widespread and previously
unrecognized evolutionary phenomenon that provides new
insights into the evolution of marine fishes and the function of
light and visual systems in a marine environment, as well as
providing a framework for the discovery of additional novel
fluorescent proteins.
Research, collecting and export permits were obtained from the
government of the Bahamas, from the Ministry of Fisheries and
Ministry of Environment, Honiara, Solomon Islands, and from the
Department of Environment, Cayman Islands Government. This
study was carried out in strict accordance with the recommenda-
tions in the Guidelines for the Use of Fishes in Research of the
American Fisheries Society and the American Museum of Natural
History’s Institutional Animal Care and Use Committee (IACUC).
Fishes were collected via SCUBA, using both standard open
circuit systems and closed circuit rebreathers, via the application of
rotenone and quinaldine to a targeted variety of shallow to deep
(mesophotic) habitats in each sampling location where collecting
was permitted.
Taxonomic field surveys of biofluorescence in marine fishes
were conducted during the following expeditions: Little Cayman
Island, January 2011, working out of the Central Caribbean
Marine Institute; the Exumas, Bahamas, May 2011 and December
2011, at the Perry Institute for Marine Science on Lee Stocking
Island; and a taxonomically comprehensive survey conducted at
numerous localities in the Solomon Islands (June–July, 2012 and
September 2013). In addition, we have supplemented these field
studies with specimens available in the aquarium trade and by
imaging specimens at aquariums after hours (e.g., Mystic
Aquarium and Institute for Exploration, Mystic, CT; Birch
Aquarium, Scripps Institution of Oceanography, La Jolla, CA).
All collected specimens were placed on ice to preserve
coloration and digitally imaged upon return to shore using Nikon
D300s, D7000, or D800 DSLR cameras affixed with either a 60 or
105 mm Nikkor macro lens under white light. Fishes were
subsequently scanned for fluorescence using bright LED light
sources equipped with excitation filters and observed using
emission filter glasses/goggles. All fluorescent fishes were then
imaged (Fig. 1) using the ‘‘Fluorescent Macro Photography’’
protocol outlined below.
The list and phylogenetic distribution of biofluorescence across
cartilaginous and bony fishes presented in Figure 2 and Table S1
are the result of this survey work, and they also include data from
[7] that specifically examined red fluorescence in some shallow,
reef-associated fishes. In addition, we have summarized other
accounts of biofluorescence in fishes from the popular literature
(underwater photography magazines and websites) and available
on the internet.
Emission Spectra
Emission spectra were collected using an Ocean Optics
USB2000+miniature spectrometer (Dunedin, FL) equipped with
a hand-held fiber optic probe (Ocean Optics ZFQ-12135).
Excitation spectra were achieved during illumination with a
band-pass filter (450–500 nm, Omega Optical, Inc., Brattleboro,
VT, or Semrock, Inc., Rochester, NY). Emission spectra were
recorded by applying the fiber optic probe to specific anatomical
parts of the individual fish specimen exhibiting biofluorescence.
This was repeated several times for each specimen to ensure the
accuracy of measurements.
Fluorescent Macro Photography
Individual fish specimens were placed in a narrow photographic
tank and held flat against a thin plate glass front. Fluorescent
macro images [736064912 (Nikon D800); 492863264 (Nikon
D7000); 218061800 pixel (Nikon D300S)] were produced in a
dark room by covering the flash (Nikon SB 600, SB 800, or SB910)
with interference bandpass excitation filters (Omega Optical, Inc.,
Brattleboro, VT; Semrock, Inc., Rochester, NY). Longpass (LP)
and bandpass (BP) emission filters (Semrock) were attached to the
front of the camera lens. A variety of excitation/emission filter
pairs were tested on each sample to elicit the strongest fluorescence
emission: excitation 450–500 nm, emission 514 LP; excitation
500–550 nm, emission 561 LP.
Phylogeny reconstruction
A majority of the DNA sequence data used in this study is from
[20], but additional sequences were obtained from many studies
[21–84]; the GenBank accession numbers for these sequences as
well as our added GenBank accession numbers (KF768155-
KF768177) can be found in Table S2. Mitochondrial and nuclear
genes were aligned using the program MAFFT v6.0 with default
parameters [85]. The phylogenetic analysis presented herein had a
total of 5,238 base pairs including: one mitochondrial gene
(cytochrome oxidase I, 812 bps), and five protein-coding genes
(glycosyltransferase gene, 732 bps; myosin heavy chain 6 alpha
gene, 737 bps; pleiomorphic adenoma protein-like 2-like gene,
659 bps; recombination activating gene 1, 1403 bps; zic family
member protein, 890 bps). For each maximum likelihood analysis,
the dataset was partitioned by individual gene fragments. A model
of molecular evolution was chosen by the program jMODELT-
EST v.2.1 [86] with the best fitting model under the Akaike
information criteria (AIC) for each individual gene partition
assigned, including: cytochrome oxidase I (GTR+I+C), glycosyl-
transferase (GTR+C), myosin heavy chain 6 alpha (GTR+I+C),
pleiomorphic adenoma protein-like 2-like gene (GTR+I+C),
recombination activating gene 1 (SYM+I+C), and zic family
member protein (GTR+I+C). Maximum likelihood analyses were
performed in GARLI v2.0 [87]. Ten separate analyses were
conducted, and the tree having the best likelihood score is
presented here (Fig. S1, Fig. 2) to evaluate evolutionary
The results presented in this study are based upon ichthyofaunal
surveys conducted during multiple expeditions to the Caribbean
and tropical Western Pacific (2011–2013), analysis of living
aquarium collections, and previous observations of biofluorescence
from the literature. Biofluorescence is phylogenetically widespread
Fish Biofluorescence
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Fish Biofluorescence
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and phenotypically variable in both cartilaginous (Chondrichthyes:
sharks and rays) and bony (ray-finned: e.g, eels, lizardfishes,
gobies, flatfishes) fishes (Figs. 1, 2, Table S1). We find biofluor-
escence to be most common and morphologically variable in
cryptically pigmented and patterned marine lineages, including
true eels (Anguilliformes), lizardfishes (Aulopiformes), scorpion-
fishes (Scorpaenoidei), blennies (Blennioidei), gobies (Gobioidei),
and flatfishes (Pleuronectiformes) (Figs. 1, 2), groups that generally
appear well camouflaged in the reef environment. With our initial
surveys, we have already identified 16 orders, 50 families, 105
genera, and more than 180 species of biofluorescent fishes, and we
have reconstructed our current understanding of the phylogenetic
distribution of biofluorescence for ray-finned fishes (Fig. 2, Table
We show that besides red fluorescence previously reported in
shallow reef-associated fishes (e.g., [7,88]), marine fishes also
commonly exhibit green fluorescence, or combinations of green
and red or orange fluorescence in unique, species-specific patterns
(Figs. 1, 3). Biofluorescent patterning in fishes ranges from simple
red, orange or green eye rings to striking, complex, species-specific
patterns of interspersed fluorescent elements, frequently compris-
ing multiple colors, on the head, jaws, fins, flank, and ventrum—
and even bright fluorescence of the entire body (e.g., chlopsid eels;
Fig. 1). Considerable interspecific variation in fluorescent emission
patterns are recorded for members of the lizardfish genus Synodus
(Fig. 3) and the goby genus Eviota (Fig. 1L, M), even among closely
related species that appear nearly identical under white light
(Fig. 3A, B).
We find biofluorescence to be widespread across cartilaginous
and bony fishes, and we show that this evolutionary phenomenon
is most common and phenotypically variable in cryptically colored
and patterned marine fishes, such as eels, lizardfishes, blennies,
scorpionfishes, gobies, and flatfishes (Figs. 1, 2). The repeated
evolution of biofluorescence combined with phenotypically vari-
able coloration (green, orange, red) and patterns in fishes may
suggest a previously unrecognized role in communication,
including mating behavior as has been observed in parrots [9].
Fluorescence may be exploited in fishes to produce visual contrast
and patterns in otherwise cryptically patterned or camouflaged
species that blend in well on the reef in shallow sunlit waters.
A few instances of green biofluorescence have also been
reported in deepwater (500–600 m) catsharks (Scyliorhinidae),
lizardfishes (Aulopiformes: Chlorophthalmidae), and an unidenti-
fied ceriantharian (Cnidaria) [88–89]. The presence of biofluor-
escence in these deepwater taxa that spend their lives primarily in
the dark, beyond the reach of the high-energy blue light necessary
for excitation of fluorescence, is curious from a functional
perspective. Biofluorescence in these taxa potentially represents
the ancestral condition in lineages whose shallower water relatives
Figure 1. Diversity of fluorescent patterns and colors in marine fishes. A, swell shark (Cephaloscyllium ventriosum); B, ray (Urobatis
jamaicensis); C, sole (Soleichthys heterorhinos); D, flathead (Cociella hutchinsi); E, lizardfish (Synodus dermatogenys); F, frogfish (Antennarius maculatus);
G, false stonefish (Scorpaenopsis diabolus); H, false moray eel (Kaupichthys brachychirus); I, false moray eel (Kaupichthys nuchalis); J, pipefish
(Corythoichthys haematopterus); K, sand stargazer (Gillellus uranidea); L, goby (Eviota sp.); M, goby (Eviota atriventris); N, surgeonfish (Acanthurus
coeruleus, larval); O, threadfin bream (Scolopsis bilineata).
Figure 2. Observed occurrences of green and red fluorescent emissions indicate the evolution of biofluorescence is widespread
across the evolutionary history of ray-finned fishes (Actinopterygii). Family-level tree showing evolutionary relationships of ray-finned
fishes inferred from maximum likelihood analysis of 221 species and six (one mitochondrial, five nuclear) genes. Note: Not all biofluorescent lineages
are shown due to sampling limitations (see Table S1, Fig. S1).
Fish Biofluorescence
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also exhibit biofluorescence (Figs. 1, 2). Some bioluminescent
(production and emission of light through a chemical reaction)
deep-sea organisms have previously been shown to exhibit
biofluorescence through a coupling of both bioluminescent and
biofluorescent systems. A heavily studied example is the crystal
jellyfish (Aequorea victoria) in which the bioluminescent system
(aequorin) produces blue light that directly excites green fluores-
cent protein (GFP) to emit green light [90], likely via a Fo¨rster
energy transfer process [91]. In another example, the deep-sea
loose-jaw dragonfish (Malacosteus) emits red light through biofluor-
escence via the absorption of blue bioluminescent light produced
by the fish, which is reemitted by a chlorophyll-like compound as
red light and is hypothesized to aid in predation [92]. In addition,
some deep-sea siphonophores also utilize bioluminescent light to
excite red biofluorescence [12].
Shallow water bony fishes generally exhibit good color vision
[93–94], a result of living in a visually complex environment; in
contrast, fishes occurring in deeper water exhibit limited color
vision due to a simpler (blue-shifted) visual environment. Recent
evidence indicates that sharks and rays also exhibit color vision
[95–96]. Many of the fishes we find to exhibit biofluorescence
(Figs. 1, 2), such as sharks, lizardfishes, scorpionfishes, labrids
(wrasses), and flatfishes, also possess yellow intraocular filters [18].
Yellow intraocular filters in the lenses and corneas of certain fishes
function as long-pass filters, thus enabling the species that possess
them to visualize and potentially exploit fluorescence to enhance
visual contrast and patterns that are unseen to other fishes and
predators that lack this visual specialization.
It has been hypothesized that some polarization sensitive
cephalopods communicate via ‘‘private’’ polarized light signals
that allow them to simultaneously remain camouflaged to
predators [97] and exploit a ‘‘hidden’’ communication mechanism
between conspecifics [98]. Cephalopods possess a rhabdomeric
visual system that enables detection of linearly polarized light and
they are able to produce polarized skin patterns using iridophores
[99], whereas many of their predators (marine mammals and some
fishes) are not sensitive to the polarization of light [100]. Likewise,
fishes that possess the necessary yellow intraocular filters for
visualizing biofluorescence could be exploiting a similar ‘‘hidden’’
light signal for a similar functional role. We found that
biofluorescent patterning was especially prominent in cryptically
patterned fishes, and that many of these lineages also possess
yellow long-pass intraocular filters that could enable visualization
of such patterns (Figs. 1, 2).
In recent years, biofluorescence has also been found in patchy
occurrences in some copepods [4] and mantis shrimp (phylum
Arthropoda) [5], amphioxus (phylum Chordata) [6], and a species
of comb jelly (phylum Ctenophora) [3]. Biofluorescence has been
shown to enhance signaling in the mantis shrimp, Lysiosquillina
glabriuscula, a species identified to have a complex system of color
visualization [5]. Additionally, there have been reports of
fluorescence signaling in butterflies [8], parrots [9], spiders [10],
and flowers [11], as well as in a deep-sea siphonophore [12].
The phylogeny presented in Figure 1 indicates that biofluores-
cence is phylogenetically widespread and phenotypically variable
across ray-finned fishes (Actinopterygii) in terms of the diversity of
patterns observed (Figs. 1, 3), emission spectra (Fig. 4), and
intensity. We observed distinct variation among lineages and
pronounced interspecific variation in emission patterns in closely
related taxa that otherwise look nearly identical under white light.
For example, closely related lizardfish species within the genus
Synodus exhibit fluorescence patterns that are notably more distinct
than their pigmentation patterns appear under daylight/white
light (Fig. 3). Considerable interspecific fluorescent pattern
variation is also observed across species in the goby genus Eviota
(Fig. 1L, M) and for chlopsid eels (Anguilliformes: Chlopsidae;
Fig. 1H, I). Our observations indicate that flatfishes exhibit
distinctly different fluorescent patterns on their sighted and blind
surfaces (fluorescence on the sighted side being primarily red
(Fig. 1B), whereas the blind side generally fluoresces green), which
is intriguing given that flatfishes are well known to flash their blind
sides to each other during mating rituals. Individuals of some other
species were found to exhibit both alternating red and green
fluorescent patterns (e.g., Fig. 1K), whereas in other lineages, only
the larval forms were observed to fluoresce (e.g., Fig. 1N,
acanthurids). Such observations in combination with pronounced
Figure 3. Top panel: Interspecific variation in fluorescent emission pattern (from top: lateral, ventral, and dorsal views) in two congeneric and
sympatric members of the lizardfish genus Synodus.A,S. synodus.B,S. saurus. Bottom panel: Interspecific variation in coloration and pigmentation
pattern under white light (top: lateral; bottom: dorsal) in same two congeneric and sympatric members of the lizardfish genus Synodus.A,S. synodus.
B, S. saurus.
Fish Biofluorescence
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interspecific variability in fluorescence emission pattern in
otherwise similarly patterned taxa suggest that intraspecific
communication is a function of biofluorescence in marine fishes,
as has been shown in other organisms with complex visual systems
(e.g., [9]). In addition, certain marine fishes (e.g., [101,102]) spawn
synchronously surrounding the full moon. Moonlight illumination
in shallow ocean waters could potentially provide the appropriate
excitation energy for green and red biofluorescence in fishes, and
as a result, species-specific biofluorescent patterning may provide
an added layer of species recognition during the spawning phase,
when fishes are particularly vulnerable to predation.
In addition, we present evidence that some fish lineages might
be utilizing fluorescence as a means of camouflage in specific
marine environments (Fig. 5; Videos S1, S2). Red and far-red
biofluorescence is a ubiquitous feature of photosynthetic organisms
due to the properties of chlorophyll and other photosynthetic
pigment complexes. The photosynthetic apparatus associated with
chlorophyll fluoresces red and provides a background of biofluor-
escence in areas of algal growth. Apart from photosynthetic
organisms, red biofluorescence also occurs due to fluorescent
proteins [4]. In two species of red biofluorescent scorpionfishes
that we imaged, individuals were observed residing on top of a
patch of red fluorescing algae (Fig. 5A). We also recorded a bream
(Scolopsis) with green fluorescent patterns on its nape swimming
within a green fluorescing Acropora coral outcrop (Fig. 5B). It would
appear that under fluorescent conditions, these species are
particularly well camouflaged in the specific environments in
which they were imaged.
In summary, the widespread nature of biofluorescence in both
cartilaginous and bony, ray-finned marine fishes, coupled with the
presence of yellow intraocular filters in many biofluorescent
lineages that would permit the visualization of fluorescent
emissions, is intriguing. Biofluorescence is most prominent and
phenotypically variable in cryptically patterned, well-camouflaged
lineages (Figs. 1, 2) that otherwise blend in with their surroundings.
Coupled with observations of notably distinct fluorescent emission
patterns among closely related species (including sister species) that
otherwise strongly resemble each other under white light/daylight
(Figs. 2, 3), suggests a intraspecific communication/species
recognition function. Conversely, we observed species that appear
to blend in with their surroundings under fluorescent lighting
conditions (Fig. 5), and that could theoretically exploit biofluor-
escence as a means of camouflage to either avoid being detected by
potential prey or to elude predators. Based on these data, the
possibility exists that marine fishes are using biofluorescence for a
variety of functions, including communication (species recognition,
mating), predator avoidance, and potentially even prey attraction/
predation. The broad phylogenetic distribution of biofluorescence
across bony fishes is consistent with its repeated independent
evolution, and its importance in the diversification of marine fishes
remains to be explored. As Johnsen [103] justly notes, the field of
biofluorescence is wide open for study and there have been far too
few studies to date, most of which have focused on cnidarians.
With the recent discovery of a novel fluorescent protein from a
vertebrate [14], we expect that biofluorescence in marine fishes
will be the subjects of many future studies, from the level of
proteins to whole organisms in their environment.
Supporting Information
Figure S1 Maximum likelihood topology of the evolutionary
relationships of ray-finned fishes inferred from the analysis of 221
species (representing more than 145 families), with six gene
fragments (one mitochondrial, five nuclear).
Table S1 Biofluorescent fishes known to date. Taxa are listed
alphabetically by Order (column 1), Family (column 2), and
Figure 4. Plot of emission spectra for representative green and
red fluorescing marine fishes, also showing the spectra for
enhanced green fluorescent protein (eGFP) for comparison. Key
to species sampled: Ray (family Urotrygonidae, genus Urobatis); Eel
(family Chlopsidae, genus Kaupichthys); Scorpionfish (family Scorpaeni-
dae, genus Scorpeana); Goby (family Gobiidae, genus Eviota).
Figure 5. Images of reef fishes fluorescing in their natural
habitat captured with a Red Epic video camera at night in the
Solomon Islands. (A) A red fluorescing scorpionfish, Scorpaenopsis
papuensis, perched on red fluorescing algae. (B) A green fluorescing
nemipterid (bream), Scolopsis bilineata,nearagreenfluorescing
Acropora sp. coralhead.
Fish Biofluorescence
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Species (column 3). Columns 4 (red) and 5 (green) contain filled
circles corresponding to the observed color of fluoresced light.
Column 6 gives AMNH catalog numbers. Taxa indicated with an
* are not included in the phylogenetic reconstruction (Fig. 2).
Table S2 GenBank accession numbers and sources for DNA
sequences utilized in the phylogenetic reconstruction shown in
Fig. 2 and Fig. S1.
Video S1 Supplementary video to accompany Fig. 5A showing a
red fluorescing scorpionfish, Scorpaenopsis papuensis, perched on red
fluorescing algae in its natural habitat. Video captured with a Red
Epic video camera at night in the Solomon Islands.
Video S2 Supplementary video to accompany Fig. 5B showing a
green fluorescing nemipterid (bream), Scolopsis bilineata, swimming
near a green fluorescing Acropora sp. coralhead. Video captured
with a Red Epic video camera at night in the Solomon Islands.
We are grateful to Ray and Barbara Dalio and the Dalio Family
Foundation, Fabio Amador and Dominique Rissolo of the National
Geographic Society/Waitt Program, Zipolo Habu Resort and Dive Gizo,
Solomon Islands, Perry Institute for Marine Science, Lee Stocking Island,
and Central Caribbean Marine Institute, Little Cayman Island, for
providing facilities, boats, submersibles, and logistical support. Research,
collecting and export permits were obtained from the government of the
Bahamas, from the Ministry of Fisheries and Ministry of Environment,
Honiara, Solomon Islands, and from the Department of Environment,
Cayman Islands Government. Thanks also to D. Harrington and T.
Romano at Mystic Aquarium and N. Hillgarth and R. Elkus at Birch
Aquarium (UCSD) for access to their collections; to M. Lombardi and J.
Godfrey for deep diving assistance; and to the J.B. Pierce Lab machine
shop for equipment design.
Author Contributions
Conceived and designed the experiments: JSS RCS WLS MPD DT VAP
DFG. Performed the experiments: JSS RCS WLS MPD DT VAP DFG.
Analyzed the data: JSS RCS WLS MPD VAP DFG. Contributed
reagents/materials/analysis tools: JSS RCS WLS MPD VAP DFG. Wrote
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Fish Biofluorescence
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... cleanerfish, hyperspectral imaging, temperate species Biofluorescence has been documented in a wide variety of terrestrial and aquatic species, including the duck-billed platypus, springhare, butterflies, parrots, scleractinian corals and over 100 species of fish (Olson et al., 2021;Sparks et al., 2014). When an organism biofluoresces, light absorbed by the organism is remitted in lower energy wavelengths (Sparks et al., 2014). ...
... cleanerfish, hyperspectral imaging, temperate species Biofluorescence has been documented in a wide variety of terrestrial and aquatic species, including the duck-billed platypus, springhare, butterflies, parrots, scleractinian corals and over 100 species of fish (Olson et al., 2021;Sparks et al., 2014). When an organism biofluoresces, light absorbed by the organism is remitted in lower energy wavelengths (Sparks et al., 2014). As light interacts with water in the marine environment, it is attenuated at different rates according to wavelength. ...
... The shorter wavelengths (blue, green) can penetrate to deeper depths, whereas longer wavelengths (orange, red) are quickly attenuated in depths >15 m (Kirk, 2011). The unique lighting conditions produced by this spectrally restricted (blueshifted) illumination allow marine organisms to exploit fluorescence to produce visual contrast and patterns (Gruber et al., 2016;Gruber & Sparks, 2021;Sparks et al., 2014). Biofluorescence in marine teleost fish may function for communication, predator avoidance or prey attraction in otherwise cryptic species (Gruber & Sparks, 2021;Vaccani et al., 2019;Sparks et al., 2014). ...
This study is the first known observation of biofluorescence in the lumpfish (Cyclopterus lumpus). Individual lumpfish were illuminated with blue excitation lighting for photography with both hyperspectral and filtered multispectral cameras. All photographed juvenile lumpfish (n = 11) exhibited green biofluorescence. Light emissions were characterised with two peaks observed at 545 nm and 613 nm, with greatest intensity along the tubercles of the high crest and the three longitudinal ridges. Further research on the dynamics of biofluorescence through the lifecycle of this species is required.
... S OME materials will absorb energy at one wavelength and emit it at another, longer wavelength; when the emission is in the visible light spectrum, we see this as fluorescence. From tree frogs to turtles, and swell sharks to serranids, there are many examples of animals that fluoresce (Sparks et al., 2014;Taboada et al., 2017;Lamb and Davis, 2020). The emitted light comes from one of two types of sources, either metabolites or fluorescent proteins Park et al., 2019). ...
... Fishes can certainly see these colors, but because water absorbs long wavelengths very efficiently, these are short range effects (Haddock et al., 2005). Most fishes that are biofluorescent have yellow intraocular pigments that act as long-pass filters which increase the contrast of the fluorescent patterns (Heinermann, 1984;Sparks et al., 2014). Since little long-wavelength light penetrates the depths, fluorescence is a way for fishes to convert shorter wavelengths into longer ones, effectively giving them a broader spectrum for concealment and communication. ...
... Short wavelength light reaches the depths where lumpsuckers breed and tend eggs (,10 m), so the red fluorescence could aid males in attracting mates. Red fluorescence would stand out against the blue-skewed environment as red wavelengths are rare or absent in the ambient light that reaches their habitat (Meadows et al., 2014;Sparks et al., 2014;Anthes et al., 2016). Additionally, the brightly fluorescing sucker disc could act as a signaling device, which would be completely hidden when the fish is attached to a substrate. ...
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Joining the ranks of vertebrates that glow is the Pacific Spiny Lumpsucker, Eumicrotremus orbis, a subtidal species widely distributed across the North Pacific Ocean. Aside from their charismatic appearance, the Pacific Spiny Lumpsucker is known for its ventral suction disc that is used to stick to substrates amid changing currents and tides. Here we show that red lumpsuckers, which are usually male and a deep red color under broad-spectrum light, fluoresce bright red under ultraviolet (UV) light and blue light (360–460 nm), while green color morphs (usually female) do not. In all color morphs, the suctorial disc glows green-yellow. The red glow of the males matches the red glow of encrusting algae in their nesting areas, while the suctorial disc may be a signaling system. The green and red fluorescence observed in red lumpsuckers is the rarest fluorescent pattern and is only seen in 17 families of marine fishes. Pacific Spiny Lumpsuckers are cryptically colored under broad-spectrum light; our observed fluorescence suggests a potential avenue of communication and camouflage in an environment where red light is absent or rare.
... It is an incredible strategy for testing the discreteness of energy levels and to separate significant data about semiconductor test creation, quantum well thickness, for checking the mono dispersity of different materials, and so on [44]. PL has been further categorized into two types namely fluorescence and phosphorescence, which will be briefly explained later [45,46]. ...
Full-text available
Luminescence or photoluminescence is a process in which electromagnetic radiations of a certain frequency are absorbed by a specific material to release photons with a lower frequency like when a UV photon is absorbed to generate a visible photon. The generation of light has been a basic human need since ancient times, and thus scientists have been very keen to find better and more efficient ways to generate light. Solid materials that exhibit luminescence are called phosphors. In the past decade, such materials have been studied very widely for their luminescent properties. In this chapter, the basics of luminescence, characteristics of luminescent materials, and types of luminescence have been discussed. The discussions are primarily dedicated to the luminescent mechanism and phosphor materials. Several concepts involved in luminescence such as charge transfer, excitation, and quenching along with luminescence lifetime have also been discussed. This chapter also provides a good introduction to the useful properties and characteristics of rare-earth (RE)-activated phosphors. The use of RE-activated phosphors for a broad variety of important applications is also discussed.
Proteins of the Green Fluorescent Protein (GFP) family, being used as genetically encoded labels, have brought fluorescence molecular imaging into the dynamic world of living cells and organisms. Flavin-, bilirubin-, and biliverdin-binding fluorescent proteins further enriched the palette of genetic markers with novel spectral and physico-chemical properties. What are the possible next steps in the development of this methodology?
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Mammals are generally brown in colour, but recent publications are showing that they may not be as uniform as once assumed. Monotremes, marsupials, and a handful of eutherians reflect various colours when lit with UV light, mostly purple. Because of these still scarce records, we aimed to explore UV reflectance among rodent genera, the most diverse mammalian group, and the group of eutherians with the most common records of biofluorescence. Here we report structures like nails and quills reflected green, but for most genera, it was faded. However, Hystrix, Erethizon, and Ctenomys showed intense and contrasting green glow, while Chaetomys presented a vivid orange anogenital. The main available explanation of fluorescence in mammals relies on porphyrin. This explanation applies to the cases like Chaetomys, where specimens showed anogenital orange biofluorescence, but does not apply to the green biofluorescence we observed. In our sample, because the structures that reflected green were all keratinized, we have reasons to believe that biofluorescence results from keratinization and is a structurally-based colouration. However, not all spines/quills equally biofluoresced, so we cannot rule out other explanations. Since Rodentia is the most common mammalian group with reports on biofluorescence, this trait likely serves various functions that match the species diversity of this group.
Smart materials with programmable shape deformation and synergistic shape/fluorescence variation are highly desired in various practical applications, such as bio-inspired multifunctional robots and machines. However, it is still quite challenging...
Full-text available
Personalized and point-of-care (POC) diagnoses are critical for ocular physiology and disease diagnosis. Real-time monitoring and continuous sampling abilities of tear fluid and user-friendliness have become the key characteristics for the applied ophthalmic techniques. Fluorescence technologies, as one of the most popular methods that can fulfill the requirements of clinical ophthalmic applications for optical sensing, have been raised and applied for tear sensing and diagnostic platforms in recent decades. Wearable sensors in this case have been increasingly developed for ocular diagnosis. Contact lenses, as one of the commercialized and popular tools for ocular dysfunction, have been developed as a platform for fluorescence sensing in tears diagnostics and real-time monitoring. Numbers of biochemical analytes have been examined through developed fluorescent contact lens sensors, including pH values, electrolytes, glucose, and enzymes. These sensors have been proven for monitoring ocular conditions, enhancing and detecting medical treatments, and tracking efficiency of related ophthalmic surgeries at POC settings. This review summarizes the applied ophthalmic fluorescence sensing technologies in tears for ocular diagnosis and monitoring. In addition, the cooperation of fabricated fluorescent sensor with mobile phone readout devices for diagnosing ocular diseases with specific biomarkers continuously is also discussed. Further perspectives for the developments and applications of fluorescent ocular sensing and diagnosing technologies are also provided.
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The vast ocean holds many unexplored organisms with unique adaptive features that enable them to thrive in their environment. The secretion of fluorescent proteins is one of them, with reports on the presence of such compounds in marine annelids being scarce. The intertidal Eulalia sp. is an example. The worm secretes copious amounts of mucus, that when purified and concentrated extracts, yield strong fluorescence under UV light. Emission has two main maxima, at 400 nm and at 500 nm, with the latter responsible for the blue–greenish fluorescence. Combining proteomics and transcriptomics techniques, we identified ubiquitin, peroxiredoxin, and 14-3-3 protein as key elements in the mucus. Fluorescence was found to be mainly modulated by redox status and pH, being consistently upheld in extracts prepared in Tris-HCl buffer with reducing agent at pH 7 and excited at 330 nm. One of the proteins associated with the fluorescent signal was localized in secretory cells in the pharynx. The results indicate that the secretion of fluorescent proteinaceous complexes can be an important defense against UV for this dweller. Additionally, the internalization of fluorescent complexes by ovarian cancer cells and modulation of fluorescence of redox status bears important considerations for biotechnological application of mucus components as markers.
Recently developed, high-efficiency, light-emitting diodes use two-dimensional photonic crystals to enhance the extraction of otherwise internally trapped light and multilayer reflectors to control the direction of light emission. This work describes the characterization of a naturally evolved light-extraction system on the wing scales of a small group of Papilio butterflies. The efficient extraction of fluorescence from these scales is facilitated by a two-dimensional photonic crystal slab that uses a multilayer to help control emission direction. Its light-extraction function is analogous to that of the light-emitting diode.
Optics--a field of physics focusing on the study of light--is also central to many areas of biology, including vision, ecology, botany, animal behavior, neurobiology, and molecular biology.The Optics of Lifeintroduces the fundamentals of optics to biologists and nonphysicists, giving them the tools they need to successfully incorporate optical measurements and principles into their research. S nke Johnsen starts with the basics, describing the properties of light and the units and geometry of measurement. He then explores how light is created and propagates and how it interacts with matter, covering topics such as absorption, scattering, fluorescence, and polarization. Johnsen also provides a tutorial on how to measure light as well as an informative discussion of quantum mechanics. The Optics of Lifefeatures a host of examples drawn from nature and everyday life, and several appendixes that offer further practical guidance for researchers. This concise book uses a minimum of equations and jargon, explaining the basic physics of light in a succinct and lively manner. It is the essential primer for working biologists and for anyone seeking an accessible introduction to optics.
Abstract DNA barcoding has been adopted as a global bio-identification system for animals in recent years. A major national programme on DNA barcoding of fish and marine life was initiated in India by the authors during 2006 and 115 species of marine fish covering Carangids, Clupeids, Scombrids, Groupers, Sciaenids, Silverbellies, Mullids, Polynemids and Silurids representing 79 Genera and 37 Families from the Indian Ocean have been barcoded for the first time using cytochrome c oxidase I gene (COI) of the mtDNA. The species were represented by multiple specimens and a total of 397 sequences were generated. After amplification and sequencing of 707 base pair fragment of COI, primers were trimmed which invariably generated a 655 base pair barcode sequence. The average Kimura two parameter (K2P) distances within species, genera, families, orders were 0.30%, 6.60%, 9.91%, 16.00%, respectively. In addition to barcode-based species identification system, phylogenetic relationships among the species have also been attempted. The neighbour-joining tree revealed distinct clusters in concurrence with the taxonomic status of the species.
We used mitochondrial (cytb, 16S) and nuclear (ITS2, S71, RAG1) sequence data to assess the degree of genetic differentiation between the recently described lacustrine Hypomesus chishimaensis from the Kuril Islands and its anadromous congener H. nipponensis from Hokkaido, Japan. The results showed that the two species are not genetically distinct at these loci. Phylogenetic trees depicted an unstructured clade consisting of individuals of both species and sequence data showed haplotypes that are shared between putative species for all markers. We conclude that H. chishimaensis is an alternative life-history type of H. nipponensis that should not be recognized at either the species or the sub-species level.
a b s t r a c t A group of small and transparent Asian noodlefishes (Osmeriformes: Salangidae) are commercially important fishery species, however, interrelationships among these fishes remain unresolved in previous studies using mitochondrial markers. We re-examine phylogenetic relationships of Salangidae by includ-ing complete taxon sampling, based on seven nuclear loci and one mitochondrial gene using a multilocus coalescence-based species-tree method. Our results show a well-resolved phylogeny of Salangidae that does not agree with previous hypotheses. The topology test suggests that our hypothesis represents the most likely phylogeny. Using the inferred species-tree as criterion, we recombine the rank of subfam-ilies and genera in the Salangidae, and erect a new genus Neosalangichthys. Our revised classification of Salangidae is well supported by reinterpreting previously proposed diagnostic characters. Finally, re-defined synapomorphic characters are used to erect a key to the genera of Salangidae. Crown Copyright Ó