Body Color Change Research Articles

Effects of light colors on the growth, body color changes, and phototactic behaviors of green, purple, and white sea cucumbers, Apostichopus japonicus

The sea cucumber (Apostichopus japonicus) is a high valuable species in Chinese aquaculture. Light significantly impacts the life cycle of sea cucumbers. However, existing studies mainly focus on the effect of light intensity and photoperiod on adult green sea cucumbers, with fewer studies on light color and inconsistent results. Research on the photoreceptive responses of different color morphs is still insufficient. Therefore, this study aims to explore the physiological and behavioral effects of different light colors on various color morphs (green, purple, white) of sea cucumbers. The results showed that short-wavelength light inhibits sea cucumber growth, while long-wavelength light and darkness promote higher growth rates. Green sea cucumbers adapted best to light stress, followed by purple and white morphs. Purple sea cucumbers grew better under long-wavelength light and darkness. Under low light, color changes in sea cucumbers were minimal. Sea cucumbers exhibited negative phototaxis to all light colors, with stronger reactions to blue and purple light, leading to stacking behavior. They aggregated less under red and yellow light, using tentacle contact to reduce light exposure. White sea cucumbers showed the most aggregation under light. The results provide a theoretical basis for further research on sea cucumber photoreception, new insights into environmental adaptation, and information for aquaculture improvement.

How does rapid body color change affect the conspicuity of lizards to their predators and conspecifics?

How does rapid body color change affect the conspicuity of lizards to their predators and conspecifics?

Effects of Light on the Fruiting Body Color and Differentially Expressed Genes in Flammulina velutipes.

Light plays vital roles in fungal growth, development, reproduction, and pigmentation. In Flammulina velutipes, the color of the fruiting body exhibits distinct changes in response to light; however, the underlying molecular mechanisms remain unknown. Therefore, in this study, we aimed to analyze the F. velutipes transcriptome under red, green, and blue light-emitting diode (LED) lights to identify the key genes affecting the light response and fruiting body color in this fungus. Additionally, we conducted protein-protein interaction (PPI) network analysis of the previously reported fruiting body color-related gene, Fvpal1, to identify the hub genes. Phenotypic analysis revealed that fruiting bodies exposed to green and blue lights were darker than those untreated or exposed to red light, with the color intensifying more after 48 h of exposure to blue light compared to that after 24 h of exposure. Differentially expressed gene (DEG) analyses of all light treatments for 24 h revealed that the numbers of DEGs were 17, 74, and 257 under red, green, and blue lights, respectively. Subsequently, functional enrichment analysis was conducted of the DEGs identified under green and blue lights, which influenced the color of F. velutipes. In total, 103 of 168 downregulated DEGs under blue and green lights were included in the enrichment analysis. Among the DEGs enriched under both green and blue light treatments, four genes were related to monooxygenases, with three genes annotated as cytochrome P450s that are crucial for various metabolic processes in fungi. PPI network analysis of Fvpal1 revealed associations with 11 genes, among which the expression of one gene, pyridoxal-dependent decarboxylase, was upregulated in F. velutipes exposed to blue light. These findings contribute to our understanding of the molecular mechanisms involved in the fruiting body color changes in response to light and offer potential molecular markers for further exploration of light-mediated regulatory pathways.

Neurotransmitter norepinephrine regulates chromatosomes aggregation and the formation of blotches in coral trout Plectropomus leopardus.

Color changes and pattern formations can represent strategies of the utmost importance for the survival of individuals or of species. Previous studies have associated capture with the formation of blotches (areas with light color) of coral trout, but the regulatory mechanisms link the two are lacking. Here, we report that capture induced blotches formation within 4-5seconds. The blotches disappeared after anesthesia dispersed the pigment cells and reappeared after electrical stimulation. Subsequently, combining immunofluorescence, transmission electron microscopy and chemical sympathectomy, we found blotches formation results from activation of catecholaminergic neurons below the pigment layer. Finally, the in vitro incubation and intraperitoneal injection of norepinephrine (NE) induced aggregation of chromatosomes and lightening of body color, respectively, suggesting that NE, a neurotransmitter released by catecholaminergic nerves, mediates blotches formation. Our results demonstrate that acute stress response-induced neuronal activity can drive rapid changes in body color, which enriches our knowledge of physiological adaptations in coral reef fish.

Examination of the effects of triacylglycerol lipase on astaxanthin conversion in the black tiger prawn Penaeus monodon

The enzyme triacylglycerol lipase (TGL) catalyses the hydrolysis of triacylglycerols, and is characterized by catalytic esterification and ester exchange functionality. However, at present, there is comparatively little information regarding the sequences and functional validation of TGLs in crustaceans. In this study, we cloned the TGL1 gene of the black tiger prawn Penaeus monodon. The full-length cDNA of PmTGL1 comprises 1807 base pairs (bp), including an 80-bp 5′-untranslated region (UTR), a 149-bp 3′-UTR, and a 1578-bp open-reading frame (ORF), and encodes a putative 525-amino acid protein of 58.71 kDa with a theoretical isoelectric point of 4.81. Homology and phylogenetic tree analyses revealed that PmTGL1 is most closely related to the TGL of Penaeus chinensis, with which it clusters in a single group (similarity of up to 97.52%). Quantitative real-time PCR analysis further revealed that PmTGL1 is most highly expressed in the shrimp hepatopancreas. Although the expression of PmTGL1 was not significantly influenced by the differences in the background colour of the rearing pond, it was significantly promoted in response to dietary supplementation with astaxanthin. As an adipokinetic hormone in P. monodon, PmRPCH (red pigment-concentrating hormone) plays an important role in body colour changes and lipid metabolism. Based on our findings, we speculate that the PmTGL1 facilitates astaxanthin metabolism in P. monodon via the hydrolysis of esterified astaxanthin to yield free astaxanthin and that the activity of TGL in these shrimps is regulated via an adipokinetic hormone cascade.

The unresolved ecological and evolutionary role of fungal fruit body coloration

Fruit body-forming fungi are hyperdiverse and of central importance for the functioning of ecosystems worldwide. They provide habitat and resources for other organisms and perform critical roles in carbon and nutrient cycling. Like in animals and plants, fungal coloration is expected to play a fundamental role in response to biotic and abiotic environments, thus providing invaluable information to predict fungal and associated diversity in the Anthropocene. Despite centuries of plant and animal coloration research, the role of fruit body colors in fungal ecology remains mostly obscure. Essential questions are unresolved, such as: How do fruit body colors function to cope with abiotic stress? Do fruit body colors function to attract dispersal vectors or prevent predation via camouflage or aposematism? What is the significance of fruit body colors for fungal fitness? What are the implications of climate change-induced fruit body color change on fungal and associated biodiversity? Here, I review existing knowledge and outline several research trajectories to better understand the ecological role of fruit body colors. Revealing climate-driven adaptations and interactions with other organisms will improve forecasts under climate change for fungal diversity and interrelated biodiversity and inform cross-taxonomic conservation strategies.

Comparative transcriptome analysis reveals growth and molecular pathway of body color regulation in turbot (Scophthalmus maximus) exposed to different light spectrum

Fish body color changes play vital roles in adapting to ecological light environment and influencing market value. However, the initial mechanisms governing the changes remain unknown. Here, we scrutinized the impact of light spectrum on turbot (Scophthalmus maximus) body coloration, exposing them to red, blue, and full light spectra from embryo to 90 days post hatch. Transcriptome and quantitative real-time PCR (qRT-PCR) analyses were employed to elucidate underlying biological processes. The results showed that red light induced dimorphism in turbot juvenile skin pigmentation: some exhibited black coloration (Red_Black_Surface, R_B_S), while others displayed lighter skin (Red_White_Bottom, R_W_B), with red light leading to reduced skin lightness (L*) and body weight, particularly in R_B_S group. Transcriptomic and qRT-PCR analyses showcased upregulated gene expressions related to melanin synthesis in R_B_S individuals, notably tyrosinase (tyr), tyrosinase-related protein 1 (tyrp1), and dopachrome tautomerase (dct), alongside solute carrier family 24 member 5 (slc24a5) and oculocutaneous albinism type II (oca2) as pivotal regulators. Nervous system emerged as a critical mediator in spectral environment-driven color regulation. N-methyl d-aspartate (NMDA) glutamate receptor, and calcium signaling pathway emerged as pivotal links intertwining spectral conditions, neural signal transduction, and color regulation. The individual differences in NMDA glutamate receptor expression and subsequent neural excitability seemed responsible for dichromatic body coloration in red light-expose juveniles. This study provides new insights into the comprehending of fish adaptation to environment and methods for fish body color regulation and could potentially help enhance the economic benefit of fish farming industry.

Ontogeny of color development in two green-brown polymorphic grasshopper species.

Many insects, including several orthopterans, undergo dramatic changes in body coloration during ontogeny. This variation is particularly intriguing in gomphocerine grasshoppers, where the green and brown morphs appear to be genetically determined (Schielzeth & Dieker, 2020, BMC Evolutionary Biology, 20, 63; Winter etal., 2021, Heredity, 127, 66). A better understanding of how these color morphs develop during ontogeny can provide valuable insights into the evolution and ecology of such a widespread color polymorphism. Here, we focus on the color development of two green-brown polymorphic species, the club-legged grasshopper Gomphocerus sibiricus and the steppe grasshopper Chorthippus dorsatus. By following the color development of individuals from hatching to adulthood, we found that color morph differences begin to develop during the second nymphal stage, are clearly defined by the third nymphal stage, and remain stable throughout the life of an individual. Interestingly, we also observed that shed skins of late nymphal stages are identifiable by color morphs based on their yellowish coloration, rather than the green that marks green body parts. Furthermore, by assessing how these colors are perceived by different visual systems, we found that certain potential predators can chromatically discriminate between morphs, while others may not. These results suggest that the putative genes controlling color morph are active during the early stages of ontogeny, and that green color is likely composed of two components, one present in the cuticle and one not. In addition, the effectiveness of camouflage appears to vary depending on the specific predator involved.

Identification and Physiological Assays of Crustacean Hyperglycemic Hormones in the Japanese Spiny Lobster, Panulirus japonicus.

The Japanese spiny lobster Panulirus japonicus lives on rocky shores and is mainly distributed along the Pacific coast around Japan. Due to the high demand for it, the development of aquaculture systems and increasing its resource volume requires further expansive production. However, a major factor preventing the establishment of aquaculture technology for this lobster is the difficulty with rearing processes from larval to juvenile production. A recent study shed light on the molecular mechanisms underlying larval development from the perspective of physiological functions of endocrine factors such as molting hormones. However, physiological studies of P. japonicus are still lacking. In decapod crustaceans, the X-organ/sinus gland complex is a well-known endocrine system that secretes the crustacean hyperglycemic hormone (CHH)-superfamily peptides that regulate growth, molting, sexual maturation, reproduction, and change in body color. In this study, we identified two CHHs from the sinus glands of P. japonicus using reversed-phase high-performance liquid chromatography in order to elucidate their physiological function for the first time.

Melanistic coloration does not influence thermoregulation in the crepuscular gecko Eublepharis macularius.

Body coloration in ectotherms serves multiple biological functions, including avoiding predators, communicating with conspecific individuals, and involvement in thermoregulation. As ectotherms rely on environmental sources of heat to regulate their internal body temperature, stable melanistic body coloration or color change can be used to increase or decrease heat absorption and heat exchange with the environment. While the function of melanistic coloration for thermoregulation increases solar radiation absorption for heating in many diurnal ectotherms, research on crepuscular and nocturnal ectotherms is lacking. Since crepuscular and nocturnal ectotherms generally absorb heat from the substrate, in these organisms melanistic coloration may have other primary functions beside thermoregulation. As such, in this work we hypothesized that the proportion of dorsal melanistic body coloration would not influence heating and cooling rates in the crepuscular gecko, Eublepharis macularius, and that changes in environmental temperature would not trigger color changes in this species. Temperature measurements of the geckos and of the environment were taken using infrared thermography and temperature loggers. Color data were obtained using objective photography and a newly developed custom software package. We found that body temperature reflected substrate temperatures, and that the proportion of melanistic coloration has no influence on heating or cooling rates or on color changes. These findings support that melanistic coloration in E. macularius may not be used for thermoregulation and strengthen the hypothesis that in animals active in low light conditions, melanistic coloration may be used instead for camouflage or other functions.

Sexual dimorphic eyestalk transcriptome of kuruma prawn Marsupenaeus japonicus

Kuruma prawn (Marsupenaeus japonicus) is a benthic decapod crustacean that is widely distributed in the Indo-West Pacific region. It is one of the most important fishery resources in Japan, but its annual catches have declined sharply since the 1990s. To increase stocks, various approaches such as seed production and aquaculture were attempted. Since the demand for important fishery species, including kuruma prawn, is expected to increase worldwide in the future, there is a need to develop new technologies that will make aquaculture more efficient. Historically, the eyestalk endocrine organ is known to consist of the X-organ and sinus gland (XO/SG) complex that synthesizes and secrets various neuropeptide hormones that regulate growth, molt, sexual maturation, reproduction, and changes in body color. In the current study, eyestalk-derived neuropeptides were identified in the transcriptome. In addition, most orthologs of sex-determination genes were expressed in eyestalks. We identified two doublesex genes (MjapDsx1 and MjapDsx2) and found that MjapDsx1 showed male-biased expression in the eyestalk ganglion with no sex-specific splicing, unlike insect species. Therefore, this study will provide an opportunity to advance the research of neuropeptides and sex determination in the kuruma prawn.

Reproductive benefits and reduced investment in parental care behavior associated with reproductive groups of males in Abudefduf troschelii.

Fishes of the family Pomacentridae present a wide diversity of mating systems, ranging from polygyny to promiscuity and from individual territorial defense to the establishment of reproductive colonies of males. The damselfish species Abudefduf troschelii has a reproductive colony mating system, in which males temporarily aggregate in reproductive areas to court and attract females. Males defend an individual territory where they receive eggs and perform paternal care behaviors for their offspring. The present study evaluated the advantages of the colonial mating system in A. troschelii. During an entire reproductive period, in a breeding colony within a rocky reef, we located, marked, geo-referenced, and measured the distances between the territories of all males. We quantified the variance among males in their patterns of paternal care investment, eggs acquired, hatching success, reproductive success, body size, and changes in body coloration. We found that males spatially distributed their nests in groups or independently (i.e., solitary nests). Nesting groups are formed by larger males that show intense nuptial coloration during the entire receptivity period. They are located centrally to the colony and consist of three to six males whose territories overlap. In contrast, small solitary males that fail to acquire or maintain nuptial coloration during the receptivity period establish their nests peripherally to the colony, away from the territories of other males. Our results highlight that the reproductive benefits of colonial nesting are unequal for males, as the spatial distribution of nests within the colony determines the reproductive success of males. Group nesting confers the highest reproductive benefits to males regarding eggs obtained, hatching success, and relative fitness and also enables males to reduce their parental investment in brood care behaviors. The preference of females for oviposition could be associated with greater intrasexual competitiveness, defense ability, body condition, or experience of group-nesting males located at the center of the colony or because their progeny will have a lower probability of predation than they would in solitary nests males.

Identification of key regulatory pathways and genes involved in the dynamic progression of pigmentation in Sinibrama taeniatus

IntorductionColoration is a prominent trait in fish that is closely linked to their market value. Fish exhibit a diverse range of body colors, making them an excellent model for studying molecular mechanisms underlying pigmentation. Although regulatory pathways involved in pigmentation have been extensively studied in model fish such as zebrafish and medaka, the presence of varying chromatophore types across different fish species suggests that fish pigmentation mechanisms are not fixed. Therefore, more studies should be conducted on non-model fish. Sinibrama taeniatus is an endemic fish in the upper Yangtze River that is highly valued for its ornamental and edible properties.MethodsIn this study, we identified three chromatophore types in S. taeniatus and investigated changes in body color, chromatophores, and pigments at different developmental stages. Subsequently, RNA-seq analysis revealed that retinol metabolism, thyroid hormone synthesis, purine metabolism, and pyrimidine metabolism pathway are closely associated with pigmentation.ResultsWeighted gene co-expression network analysis (WGCNA) identified several hub genes, including mitf, wnt 9a, wnt10b, wnt11, adcy5, edn1, adcy8, and rdh8, that may play an important role in pigmentation.DiscussionOverall, our findings provide valuable insights into the role of genes and pathways in fish pigmentation and offer useful information for body color-based molecular breeding programs in aquaculture.

Atmosphere and room temperature plasma alters the m6A methylome profiles and regulates gene expression associated with color mutation in clownfish (Amphiprion ocellaris)

Since the release of the movie Finding Nemo, clownfish have been known and loved by many people. Clownfish have a very vivid skin color and extreme ornamental value. However, there are few species of clownfish, which greatly limits the breeding of new varieties. In this study, the Atmosphere and room temperature plasma (ARTP) method was used to treat clownfish-fertilized eggs and successfully screened out mutants that exhibited a skin color change from black to red in their offspring. To elucidate the molecular mechanism underlying this color mutation, more than 17,000 methylated peaks were obtained via m6A-specific methylated RNA immunoprecipitation with next-generation sequencing (MeRIP-seq). These modification sites were mainly distributed around stop codons, and the number of corresponding genes exceeded 10,000. Further RNA sequencing (RNA-seq) of clownfish before and after the mutation was performed identified 883 genes that exhibited significant differences between the two samples, among which 152 interaction genes showed significant differences in the m6A methylated level and gene expression level. The results of a functional analysis showed that the phosphatidylinositol-3-kinase (PI3K)-serine/threoninekinase (Akt) pathway and its related signal pathways may play an important role in skin color change. In particular, genes such as mitogen activated protein kinase kinase 1 (MAP2K1), insulin―like growth factor―l (IGF1), and fibroblast growth factor 1 (FGF1) may play key roles in the accumulation of melanin in clownfish, and the homeobox-protein-encoding empty spiracles homeobox 2 (EMX2) and mesenchyme homeobox (MEOX2) genes may be important for determining the regions of accumulation of this skin pigment. Our results provide a new reference for the genetic breeding of clownfish and lay a foundation for further understanding the molecular mechanism underlying body color changes in clownfish.

Sexual dimorphism in dynamic body color in the green anole lizard

Animals capable of rapid (i.e., physiological) body color change may use color to respond quickly to changing social or physical environments. Because males and females often differ in their environments, the sexes may use changes in body color differently, reflecting sexual dimorphism in ecological, behavioral, or morphological traits. Green anole lizards, Anolis carolinensis, frequently switch their dorsal body color between bright green and dark brown, a change that requires only seconds, but little is known regarding sexual dimorphism in their color change. We tested three hypotheses for the function of body color (thermoregulation, camouflage via background-matching, and social communication) to determine the ecological role(s) of physiological color change in anoles. First, we examined instantaneous body color to determine relationships between body color and body temperature, substrate color and type, and whether these varied between the sexes. Next, we examined the association between color change and behavioral displays. Altogether, we found that males were more likely to be green than females, and larger lizards were more often green than smaller ones, but there was no evidence that anole body color was associated with body temperature or background color during the summer breeding season. Instead, our results show that although the sexes change their color at approximately the same rates, males changed color more frequently during social displays, while females remained green when displaying. In sum, social communication appears to be the primary function of anole color change, although the functions of body color may differ in the nonbreeding season.Significance statementMany animals can change their body color in response to their environments, and in many species, males and females experience different environments. In this study, we examined whether the sexes of green anole lizards use the ability to rapidly change their body color between green and brown for different functions. We found that, when a lizard was first sighted, its body color did not appear to match its background color in either sex (suggesting that color change does not contribute to avoidance of detection by potential predators), and body color was not associated with temperature for either sex (i.e., color was unlikely to influence body temperature). Yet, males changed color more often when performing social displays to other lizards, while females remained green during social displays. Thus, rapid color change plays an important role in social communication in both sexes, highlighting how males and females may use the same behavior to convey different messages.

Anomalous Coloration of Indo-Pacific Humpback Dolphins off Southern China

The Indo-Pacific humpback dolphin is characterized by a particular ontogenic change in body color from dark gray at birth to pure white (or with a few dark-gray spots) after reaching adulthood. Here, we report a spectrum of anomalous body color patterns observed on Indo-Pacific humpback dolphins off southern China. The occurrence of hypopigmentation and hyperpigmentation was described and compared among six putative dolphin populations. Low rates of anomalies in body color patterns were observed (<1%), except for hypopigmentation, which was prevalent in dolphins residing in the mid-Pearl-River-Delta region (3.3%).

Rapid bluing and slow browning: reversible body color change according to ambient temperature in damselfly Indolestes peregrinus (Ris, 1916)

AbstractVariation in body color occurs in many animals, and its function differs by species. Some species use multiple colors to create different effects. Most dragonflies change their body color unilaterally with maturation, whereas in a few species these changes are reversible. Both sexes of the damselfly Indolestes peregrinus show temperature‐dependent reversible body color changes, with a brown color when the ambient temperature decreases and a blue color when the temperature increases. To elucidate the temperature range at which this color change occurs and the exact elapsed time for the color change, laboratory experiments were conducted to determine whether the time required for body color change was related to ambient temperature and whether sex differences affected this duration. The body color and time required for the change were recorded under four temperature conditions. Bluing was completed in a few minutes, whereas browning took several hours. Moreover, sexual differences were observed, whereby males showed a more rapid transformation to blue than that of females. Our results suggest that the rapid bluing has some importance in this species, especially in males.

Photochromic contrast optimization based on hafmium-based ceramics for optical information storage: Component adjustment and ion-doping

Herein, we report strategies combining component adjustment and ion doping for the development of photochromic materials with high color-changing contrast. Sr0.05Ba0.95HfO3: Eu3+ ceramics showed reversible photochromism from off-white to dark brown under the alternating action of 254 nm UV light and heat treatment at 300 °C. This is caused by the capture and release of electrons by defects in the Sr0.05Ba0.95HfO3: Eu3+ host such as oxygen vacancies. Under this strategy, the maximum photochromic contrast ratio of 44.81% is achieved, which is a great improvement compared to pure SrHfO3 (15.91%) and BaHfO3 (14.98%). The luminescence quenching behavior based on the photochromic reaction can effectively modulate the emission of Eu3+. The reversible photochromic properties of Sr0.05Ba0.95HfO3: Eu3+ ceramics can be used for repeated writing and erasing of optical information, and the significant body color change improves its resolution in pattern information storage.

The background adaptation of the skin color in the loach Paramisgurnus dabryanus

Body color change is one of the most important manifestations of fish adaptation to the environment. In this study, the body color change of two kinds of loach (Paramisgurnus dabryanus) with different body colors under five different background colors was first studied. It was found that the color of dorsal skin of gray-black loach changed more than that in the abdominal skin, and the L* value of the dorsal skin on the red, yellow and white backgrounds changed significantly (P < 0.05). Compared with the gray-black loach, the body color of golden loach changed less, and the L* value of the back skin and the abdomen skin did not change significantly (P > 0.05). Furthermore, the dynamic change characteristics and adaptive mechanism of body color in different background colors was studied in a black-white background conversion model. The results showed that the greyscale color decreased from 72.33 ± 2.55–38.22 ± 2.33, the melanocytes changed from dendritic to mass, and the L* value of the back skin increased significantly (P < 0.05) after transferring the loach from a black background to a white background. The concentration of plasma ATCH decreased significantly (P < 0.05), and that of MCH increased significantly (P < 0.05). When transferring the loach from a white background to a black background, these indicators showed an opposite trend. This study provides a scientific basis for healthy farming of loach and understanding the background color adaptation mechanism of fish.

Melatonin modulates the hypothalamic-pituitary neuroendocrine axis to regulate physiological color change in teleost fish.

Melatonin (MT) is a crucial neuroendocrine regulator of various physiological activities in vertebrates, especially in circadian or seasonal rhythm control. In the present study, the large yellow croaker (Larimichthys crocea), a marine bony fish with circadian body color change behavior, is chosen for functional investigation on teleost MT signaling systems that remain uncharacterized. All five melatonin receptors (LcMtnr1a1, LcMtnr1a2, LcMtnr1b1, LcMtnr1b2, and LcMtnr1c) were significantly activated by MT, triggering extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation through different G protein coupling signaling pathways, with exclusive Gαi-dependency for LcMtnr1a2 and LcMtnr1c, and Gαq-dependency for two LcMtnr1b paralogs, whereas LcMtnr1a1 activated Gαi and Gαs dual-dependent signaling pathways. A comprehensive model of the MT signaling system in the hypothalamic-pituitary neuroendocrine axis was further constructed based on ligand-receptor interaction analysis using single-cell RNA-seq data, as well as spatial expression patterns of Mtnrs and related neuropeptides in central neuroendocrine tissues. A novel regulatory pathway of MT/melanin-concentrating hormone (MCH) and MT/(tachykinin precursor 1 (TAC1)+corticotropin-releasing hormone (CRH))/melanocyte-stimulating hormone (MSH) was discovered that functions in chromatophore mobilization and physiological color change and was further validated by pharmacological experiments. Together, our findings define multiple intracellular signaling pathways mediated by L. crocea melatonin receptors and provide the first in-depth evidence that uncover the upstream modulating roles of the MT signaling system in the hypothalamic-pituitary neuroendocrine axis of a marine teleost species, particularly in chromatophore mobilization and physiological color change.