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The epithelial layer of the B. boddarti fused pelvic fins and P. variabilis unfused pelvic fins, stained using hematoxylin and eosin (HE), modified acid-fast (MAF), and periodic acid-Schiff (PAS) shows the size differences in two mudskipper species and histological cell components. Notes: surface of epithelia consisted of flat-shaped cells (ep), middle layer consists of swollen cell with big vacuoles (mid), basal layer consists of cylindrically-shaped cells (bl), mucous cell (mc), secretory mucous cells (smc), and blood vessel, f. Magnification: 20 9 10. Scale bar = 20 μm
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Two species of mudskipper are identified with different behaviours, which are related to their pelvic fin morphologies. Periophthalmus variabilis has unfused pelvic fins and is capable to climb on the vertical substrate. Another species, Boleophthalmus boddarti has fused pelvic fins which supports the fish mobility across the muddy substrate. In co...
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... cell, further discussed later). Under HE staining, the nuclei of epithelial cells appear dark. Additionally, in the epithelial layer, there are mucous cells which appear due to the MAF staining as round and ovoid in shape, in adjacent amongst the flat epithelial cells. The secreted mucous is visible in magenta colouration under PAS staining (Fig. 7). The mudskippers use a mucous layer that serves as an antifriction protectant for the surface epithelial layer ( Zhang et al. 2000;Kardong 2009) and to assist attachment to the substrate by mediating Stefan adhesion, which is greatly increased in higher viscosity by the presence of mucus ( Wicaksono et al. 2016). Mucous in the skin ...
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... region appears dark with nuclei arranged in the centre of each cell. The epithelial layer of the pelvic fin is slightly thicker in P. variabilis (43.6 lm) than in B. boddarti (33.1 lm). The difference of thickness between the two species occurs most prominently in the middle section of the epidermal layer, which is abundant with swollen cells (Fig. 7). This thicker epithelial layer in the process of P. variabilis is assumed to provide greater protection from friction while walking on land and when climbing trees, and is thus effectively works as a friction barrier than in aquatic B. ...
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... mucous secreting cells are found most abundantly in the pelvic fins of P. variabilis within the epidermal layers ( Fig. 7; Table 2). The extraneous mucous cells could imply to more secretion of mucous in P. variabilis, to reduce the surface damages during terrestrial locomotion in both crutching and climbing in drier terrestrial area. Contrast to B. boddarti, which has fewer mucous cells but retains epidermal hydration by remaining in muddy and aquatic ...
Citations
... Mudskippers can breathe through their skin and the lining of their mouth and throat when these surfaces are moist, facilitating direct atmospheric gas exchange (Beon et al., 2013;Damsgaard et al., 2020;Graham et al., 2007). Maintenance of hydration is critical for mudskippers, not only for their general survival but also to facilitate their unique cutaneous and buccopharyngeal respiration (Hidayat et al., 2022). On land, mudskippers use their protrusible mouths to effectively capture prey, contrasting with their aquatic behavior where they exhibit typical fish suction feeding (Sponder & Lauder, 1981). ...
... Although separated pelvic fins in mudskippers may enhance the range of motion and provide advantages in weight support, positioning, and climbing abilities (Hidayat et al., 2022;Wicaksono et al., 2016), this trait is not found uniformly present across all mudskipper species. It is primarily observed within specific genera of the along with other terrestrial mudskippers such as P. schlosseri, P. ...
... Hasil penelitian Rohmawati et al. (2021) menemukan bahwa B. boddarti memiliki kecenderungan hidup di ekosistem mangrove yang berada di tepi pantai dengan kelimpahan yang tinggi. Secara umum, kehidupan Ikan Tembakul sangat dipengaruhi oleh karakteristik substrat (Mahadevan and Ravi, 2015) dan kondisi pasang surut (Ravi, 2013), dimana ikan tersebut akan memanjat pada akar dan batang mangrove, berjalan dan menggali lubang di lumpur (Hui et al., 2019;Hidayat et al., 2022). Karakteristik Ikan Tembakul yang unik membuat ikan tersebut banyak dijadikan sebagai biomonitoring untuk menentukan tingkat pencemaran logam berat (Sangur et al., 2021;Looi et al., 2021), khususnya di ekosistem mangrove. ...
Pemangkat is a coastal area in Sambas Regency which has a mangrove ecosystem. One of the biota found in mangrove forest areas is the Giant Mudskipper. This fish is often used as an environmental bioindicator due to its characteristics of living in the intertidal zone and being able to absorb and accumulate metals. Heavy metal pollution in marine and coastal areas has become a global problem that causes negative impacts on ecosystems, biota, and human health. One of the heavy metals that can pollute waters due to fishing and port activities is lead (Pb). Pemangkat is one of the centers of capture fisheries activities in West Kalimantan. Therefore, this research aims to analyze the content of the heavy metal of Pb in water, sediment, and Mudskipper in the Pemangkat mangrove ecosystem, Sambas, West Kalimantan. The Pb content in water, sediment, and Giant mud skipper samples was analyzed using an Atomic Absorption Spectrophotometer (AAS) at a wavelength of 283.3 nm. Accumulation of heavy metal in the biota was determined by the bioconcentration factor (BCF). The concentration of lead metal (Pb) in water and sediment samples was highest at Station II, such as 0.40 mg/L and 0.25 mg/L respectively. The metal content of Pb in Giant Mudskipper was highest at Station I (0.224 mg/kg). The BCF values for Giant Mudskipper at Stations I and II were 1.18 and 0.86. Keywords: Lead (Pb), Mangrove, Mudskipper, Boleopthalmus. Abstrak Pemangkat merupakan wilayah pesisir di Kabupaten Sambas yang memiliki ekosistem mangrove. Salah satu biota yang hanya ditemukan di daerah hutan mangrove adalah ikan tembakul. Ikan ini sering dijadikan bioindikator lingkungan dikarenakan karakteristiknya yang hidup di zona intertidal yang mampu menyerap dan mengakumulasi logam. Pencemaran logam berat di wilayah laut dan pesisir telah menjadi permasalahan global yang menyebabkan dampak negatif bagi ekosistem, biota, dan kesehatan manusia. Salah satu logam berat yang dapat mencemari perairan dengan adanya aktivitas perikanan dan pelabuhan adalah logam Pb. Pemangkat adalah salah satu sentra kegiatan perikanan tangkap di Kalimantan Barat. Oleh karena itu, penelitian ini bertujuan untuk menganalisis kandungan logam berat Pb di air, sedimen, dan ikan tembakul di ekosistem mangrove Pemangkat, Sambas, Kalimantan Barat. Kandungan Pb di sampel air, sedimen dan ikan tembakul dianalisis dengan menggunakan Spektrofotometer Serapan Atom (SSA) pada panjang gelombang 283,3 nm. Akumulasi logam berat pada biota ikan tembakul ditentukan dengan faktor biokonsentrasi (BCF). Konsentrasi logam timbal (Pb) pada sampel air dan sedimen tertinggi pada Stasiun II, yaitu: 0,40 mg/L dan 0,25 mg/L secara berurutan. Kandungan logam Pb pada ikan tembakul tertinggi pada Stasiun I, yaitu 0,224 mg/kg. Nilai BCF ikan tembakul di Stasiun I dan II adalah 1,18 dan 0,86. Kata kunci: Timbal (Pb), Mangrove, Tembakul, Boleopthalmus
... terrestrial locomotion via pectoral fins, and greater immunological protection against pathogens (You et al. 2018). The versatility of the fish is further reflected in the variety of pelvic fin morphologies, which suggest their adaptability to both terrestrial and aquatic environments (Hidayat et al. 2022). In addition to their unique adaptations, mudskipper fish have the potential as a source of food, as they are rich in carbohydrates, lipids, proteins, and well-balanced amino acids (Duggal et al. 2020;Mahadevan et al. 2021). ...
Mudskippers are commonly cryptic species, making identification based solely on morphological characteristics challenging. This study used the DNA barcoding method to identify mudskipper species based on the COI mitochondrial gene. The analysis revealed two distinct species, P. kalolo (20 samples) and P. argentilineatus (3 samples) with high GC contents ranging from 42.94-45.2%. The genetic divergence analysis of P. kalolo showed that they divided into two clades, while P. argentilineatus is divided into three clades with two of the clades (C and D) still conspecific groups, and those two clades with clade E exhibit a genetic distance greater than 3.5%, suggesting the presence of cryptic species. These findings provide valuable insights into the intraspecies genetic diversity of mudskippers in Indonesia, which could have essential implications for conservation efforts and highlight the potential of DNA barcoding as a powerful tool for the identification of cryptic species. Further research combining molecular and morphological identification could lead to a more comprehensive understanding of species identification and help address the challenges posed by cryptic species.
... Therefore, the loss of aanat1a is speculated to keep high dopamine levels in retina, and therefore help the mudskippers retain a good aerial vision [8] so as to be able to see clearly on land for escape or predation [71]. Although both Periophthalmus species spend more time on land than BP [8,73], the loss of aanat1a gene in PM but not in PMO (as previously reported existence in BP) suggests that PM may have a better air vision than both PMO and BP [8]. Such a tiny variation within the genus Periophthalmus exemplifies to prove a step-by-step evolution for the mudskippers' water-to-land adaptation. ...
Introduction:
Mudskippers are a large group of amphibious fishes that have developed many morphological and physiological capacities to live on land. Genomics comparisons of chromosome-level genome assemblies of three representative mudskippers, Boleophthalmus pectinirostris (BP), Periophthalmus magnuspinnatus (PM) and P. modestus (PMO), may be able to provide novel insights into the water-to-land evolution and adaptation.
Methods:
Two chromosome-level genome assemblies for BP and PM were respectively sequenced by an integration of PacBio, Nanopore and Hi-C sequencing. A series of standard assembly and annotation pipelines were subsequently performed for both mudskippers. We also re-annotated the PMO genome, downloaded from NCBI, to obtain a redundancy-reduced annotation. Three-way comparative analyses of the three mudskipper genomes in a large scale were carried out to discover detailed genomic differences, such as different gene sizes, and potential chromosomal fission and fusion events. Comparisons of several representative gene families among the three amphibious mudskippers and some other teleosts were also performed to find some molecular clues for terrestrial adaptation.
Results:
We obtained two high-quality haplotype genome assemblies with 23 and 25 chromosomes for BP and PM respectively. We also found two specific chromosome fission events in PM. Ancestor chromosome analysis has discovered a common fusion event in mudskipper ancestor. This fusion was then retained in all the three mudskipper species. A loss of some SCPP (secretory calcium-binding phosphoprotein) genes were identified in the three mudskipper genomes, which could lead to reduction of scales for a part-time terrestrial residence. The loss of aanat1a gene, encoding an important enzyme (arylalkylamine N-acetyltransferase 1a, AANAT1a) for dopamine metabolism and melatonin biosynthesis, was confirmed in PM but not in PMO (as previously reported existence in BP), suggesting a better air vision of PM than both PMO and BP. Such a tiny variation within the genus Periophthalmus exemplifies to prove a step-by-step evolution for the mudskippers' water-to-land adaptation.
Conclusion:
These high-quality mudskipper genome assemblies will be valuable genetic resources for in-depth discovery of genomic evolution for the terrestrial adaptation of amphibious fishes.
... This Genus occupies primary (organisms that obtain energy from producers) and secondary positions (organisms that obtain energy from primary consumers) in the food chain despite their very small size , inhabiting muddy habitats, sandy beaches, and mangrove areas (Mahadevan and Ravi 2015). Mudskippers' daily behavior is closely related to tidal rhythm (Ravi 2013), where they climb mangrove roots, walk on mudflats, and dig burrows in mud (Ansari et al. 2014;Hui et al. 2019;Hidayat et al. 2022). ...
Baderan DWK, Aydalina RV, Hamidun MS. 2023. Morphological characteristics and biodiversity of mudskipper fish (Periophthalmus: Gobiidae) in mangrove ecosystem of coastal Bay of Tomini, Gorontalo Province, Indonesia. Biodiversitas 24: 498-507. The southern sea area of Gorontalo Province is part of Tomini bay, the biggest bay in Indonesia. This area has a unique biodiversity and is Sulawesi endemic. The mangrove forest in the coastal bay of Tomini Boalemo is one of the habitats for flora and fauna, a place for spawning, nurturing, and food hunting for fish. The mudskipper is a fish that lives in the mangrove area. This study aims to reveal the morphological characteristics and biodiversity of mudskipper (Periophthalmus: Gobiidae) in the ecosystem of Tomini Boalemo coastal bay of Gorontalo Province. This study employed a quantitative descriptive that also implemented purposive sampling as the sampling method in three ecosystem stations of Tomini Boalemo coastal bay (Dulupi, Bajo, and East Pentadu mangrove). The mudskippers were collected manually when the water was receding using a fish net. The sample which had been collected were then identified based on 22 morphological, 24 morphometric, and seven meristic characteristics. The identification results were then compared with the identification key. The mudskippers' species were then analyzed to determine the species' biodiversity (diversity, evenness, species richness, and dominance indexes). The research result revealed five species from Periophthalmus Genus: Periophthalmus argentilineatus, Periophthalmus kalolo, Periophthalmus malaccensis, Periophthalmus minutus, Periophthalmus variabilis, with total individuals 561. The score of H?: 1.09 showed that the diversity of mudskipper fish was categorized as medium. The evenness index was 0.99 obtained from 3 observation stations, while the lowest dominance index was on station II with a score of 0.34, and the score of R1 in each station was respectively (0.19); (0.36); and (0.2). The results of this study could be used as a database for the sustainable management of Tomini Bay to tackle the threats of species extinction through aquatic life protection and preservation to arrange the natural balance and support the availability of the coastal resource for future generations.
The striated frogfish (Antennarius striatus), a member of the sub-order Antennarioidei within the order Lophiiformes, possesses remarkable adaptations. These include the ability to modulate body coloration for camouflage, utilize bioluminescent esca for predation, and employ elbow-like pectoral fins for terrestrial locomotion, making it a valuable model for studying bioluminescence, adaptive camouflage, fin-to-limb transition, and walking-like behaviors. To better study and contribute to the conservation of the striated frogfish, we obtained the micro-CT image of the pectoral fin bones and generated a high-quality, chromosome-level genome assembly using multiple sequencing technologies. The assembly spans 548.56 Mb with a contig N50 of 21.05 Mb, and 99.35% of the genome is anchored on 24 chromosomes, making it the most complete genome available within Lophiiformes. The genome annotation revealed 28.43% repetitive sequences and 23,945 protein-coding genes. This chromosome-level genome provides valuable genetic resources for frogfish conservation and offers insights into the genetic mechanisms underlying its unique phenotypic evolution. Furthermore, it establishes a foundation for future research on limb development and adaptive camouflage in this species.
The improvement and decreasing costs of third‐generation sequencing technologies has widened the scope of biological questions researchers can address with de novo genome assemblies. With the increasing number of reference genomes, validating their integrity with minimal overhead is vital for establishing confident results in their applications. Here, we present Klumpy, a tool for detecting and visualizing both misassembled regions in a genome assembly and genetic elements (e.g. genes) of interest in a set of sequences. By leveraging the initial raw reads in combination with their respective genome assembly, we illustrate Klumpy's utility by investigating antifreeze glycoprotein ( afgp ) loci across two icefishes, by searching for a reported absent gene in the northern snakehead fish, and by scanning the reference genomes of a mudskipper and bumblebee for misassembled regions. In the two former cases, we were able to provide support for the noncanonical placement of an afgp locus in the icefishes and locate the missing snakehead gene. Furthermore, our genome scans were able identify an unmappable locus in the mudskipper reference genome and identify a putative repetitive element shared among several species of bees.
