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Signal theory predicts organisms should evolve signals that are conspicuous to intended receivers in natural signalling environments. Cleaner shrimps remove ectoparasites from reef fish clients and many signal their intent to clean by whipping long, white antennae. As white is a reliably conspicuous colour in aquatic environments, we hypothesized that selection has acted to increase broad-spectrum antennal reflectance in cleaners. Using scanning electron microscopy, optical models and reflectance measurements, we found that the antennae in three obligate cleaner species from two families (Palaemonidae and Lysmatidae) had thick (∼6 µm) chitinous layers or densely packed high refractive index spheres (300-400 nm diameter), which models show increase reflectance (400-700 nm). Two facultative and non-cleaning species had no visible antennae ultrastructure beyond the chitinous exoskeleton. Antennae reflectance was significantly higher in obligate cleaners than in facultative and non-cleaning species. Our results suggest that some obligate cleaners may have evolved ultrastructures that increase the conspicuousness of their antennae as signals.

Simple Summary: The role of fatty acid transport protein 1 (FATP1) in decapod crustaceans is still poorly understood. In this study, we cloned the FATP1 cDNA from the mud crab Scylla paramamosain, identified its sequence features and tissue distribution pattern and analyzed its roles in lipid metabolism in vivo. We found that FATP1 is involved in long-chain polyunsaturated fatty acid metabolism and deposition in crustaceans, which provides new information for understanding the function of FATP1 in invertebrates. In mammals, fatty acid transport protein 1 (FATP1) plays important roles in cellular uptake and activation of long-chain fatty acid (LCFA), especially in processes of transportation, oxidation and triacylglycerol synthesis. However, the role of FATP1 in invertebrates, especially decapod crustaceans, is still poorly understood. In this study, the cDNA of a FATP1 gene from a decapod crustacean, mud crab Scylla paramamosain, was cloned and functionally characterized. The FATP1 gene encoded a polypeptide consisting of 643 amino acids that exhibits all the typical features of the FATP family and shares high homology with the other FATP orthologs of crustaceans. The relative mRNA expression levels of FATP1 were observed to be higher in metabolically active tissues such as hepatopancreas, stomach and gill than in other crab parts. Knockdown of the FATP1 mRNA in vivo significantly reduced triacylglycerols and total lipid levels in the hepatopancreas, accompanied by an increase in the expression of genes related to fatty acid transportation, allocation and hydrolysis, including long-chain acyl-CoA synthetase 3/4 (ACSL3/4) and carnitine palmitoyl transferase 1 (CPT1), and a decrease in the expression of genes related to fatty acid synthesis such as acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) in the hepatopancreas. Furthermore, increased dietary n-3 long-chain polyunsaturated fatty acid (LC-PUFA) levels resulted in the up-regulation of the FATP1 expression in the hepatopancreas, accompanied by an increase in LC-PUFA content, especially eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), in both polar (PLs) and neutral lipids (NLs) in the hepatopancreas and muscles of crabs. These findings suggested that the FATP1 gene identified in S. paramamosain might play important roles in regulating long-chain fatty acid metabolism and deposition in crustaceans. [ABSTRACT FROM AUTHOR]

Norway lobster Nephrops norvegicus, a prized decapod crustacean species, is found at different depths across the East Atlantic Ocean and Mediterranean Sea. Despite management efforts, the stocks are globally characterised as overexploited. In the present study, the impact of biogeographical boundaries on the phylogeographical and demographic population status was investigated within the Adriatic Sea, addressing important genetic indices for decapod functional conservation management. Central Mediterranean, Adriatic Sea A total of 482 individuals of Nephrops divided into the 12 samples were collected across biogeographical range of the Adriatic Sea. Using the mtDNA D‐loop and microsatellite markers, methods of phylogeography and seascape genetics were applied to infer offshore versus coastal population divergence, demography and structure. Significant findings include genetic differentiation between offshore and coastal samples, with higher diversity indices in open waters. The limited gene flow observed between these two areas emphasises the self‐sustained nature of coastal populations. Recent demographic changes in coastal populations reflect geographical constraints, fishing pressures and fluctuations in self‐recruitment success. Additionally, the study reveals historical biogeographic events shaping the Adriatic populations, with evidence suggesting lineage divergence during the upper Pleistocene and postglacial recolonisation from southern Adriatic refugia. The role of biogeographical conditions in shaping genetic structure and limited gene flow between inshore and offshore areas underscore the need for improved management strategies, emphasising the importance of marine protected areas in conserving coastal populations and maintaining overall genetic diversity of the Norway lobster in the Adriatic Sea. Genomic monitoring within current management practices is recommended. [ABSTRACT FROM AUTHOR]

Simple Summary: Most of the ecosystems around the world are experiencing high levels of stress. Invasive species are one of the major threats to biodiversity. To successfully prevent and manage this conservation issue, a good understanding of ecological and biological processes involving the native and introduced species is required. This is often challenging due to the interaction of many stressors within an ecosystem, hindering direct changes caused by the invader. Here, we present a unique situation where an invading snow crab is the only disturbing factor in the benthic ecosystem of an arctic fjord. This study looks at how the crabs' feeding habits change as the invaded ecosystem degrades due to their foraging. Stomach content and stable isotope analyses have revealed that while the prey items have changed, and crabs are forced to feed on less accessible and less nutritional food, their trophic position has not altered. Changes in feeding habits have occurred within the same trophic level. Following the depletion of most nutritional prey items, the number of crabs in the bay has collapsed. We expect a further decrease in crab numbers, a possible partial restoration of the benthic community, and a repeat of the cycle after new settlements of young crabs. The introduction of a new species can lead to substantial changes in a new ecosystem. Local and introduced species' survival depends on their ability to adapt to the new environment. Studying such adaptations is often hindered by multiple factors affecting the ecosystem. The introduction of a large predatory snow crab, Chionoecetes opilio, into the Kara Sea, is a unique invasive species affecting an otherwise undisturbed ecosystem. The crab has caused drastic changes in the macro- and megabenthic taxonomic structure, abundance, and biomass of the most common species in an Arctic fjord, Blagopoluchiya Bay. Stomach content and stable isotope analysis were applied to study crabs' feeding habits. As the abundance of the most common prey items diminished, the crabs switched to other less accessible food. Prior to substantial changes in benthic communities, the diet of the snow crabs was similar to that of other invaded and native areas, where animal food predominates. However, with the degradation of the ecosystem, detritus contribution has substantially increased. The changes in prey items did not change the crab's trophic status, and they continued to feed within the same trophic niche. In the depleted benthic communities of Blagopoluchiya Bay, the snow crab is forced to use all available food sources. [ABSTRACT FROM AUTHOR]

The link between the northeastern Atlantic and Mediterranean Sea created by the Strait of Gibraltar and the adjacent Iberian and Moroccan coasts marks remarkable transition areas between distinct environments that harbour a diverse mixture of species. The area is interesting regarding marine connectivity and the transport of pelagic invertebrate larvae, crucial knowledge to manage over-exploited populations, and minimize the impacts of climate change and anthropogenic activities. Biophysical models were developed, combining oceanic and particle-tracking Lagrangian simulations with in situ zooplankton distribution data. The conditions driving the larval exchange between the sub-basins and the connectivity throughout the region were explored, using crustacean decapod larvae as biological references. The potential exchange between both sub-basins was confirmed, although specific larval traits revealed contrasting scenarios. The simulations showed that slope-dwelling and mesopelagic larvae have advantage when crossing from the Alboran into the Atlantic, in comparison with shelf-dwelling and epipelagic larvae. Transport pathways and retention areas were identified, and passive drifts were shown to increase the dispersal range of the simulations. The spatial origin of the larval release, larval duration, vertical distribution, and the interaction of larvae with the oceanic features are presented as the main factors impacting the effective larval input into the Atlantic or Mediterranean basins. [ABSTRACT FROM AUTHOR]

Based on a long-term dataset of species composition and infestation levels of associated organisms on the invasive Barents Sea red king crab, a multivariate analysis was conducted to determine the contributions of biotic and abiotic factors to the fouling community structure. Results indicate that host size and exoskeleton age were the most significant factors for diversity indices and infestation intensity. Abiotic factors played a lesser role in the formation of fouling communities. Temperature conditions during the mass molting periods were found to have significant effects, apparently acting as a trigger for the primary settlement of crab shells by benthic organisms. Our data not only provide new insights into the formation of fouling communities of decapod crustaceans, but also provide valuable information for further studies on the adaptation process of the red crab to the conditions of the Barents Sea. [ABSTRACT FROM AUTHOR]

In the dark, expansive habitat of the deep sea, the production of light through bioluminescence is commonly used among a wide range of taxa. In decapod crustaceans, bioluminescence is only known in shrimps (Dendrobranchiata and Caridea) and may occur in different modes, including luminous secretions that are used to deter predators and/or from specialised light organs called photophores that function by providing camouflage against downwelling light. Photophores exhibit an extensive amount of morphological variation across decapod families: they may be internal (of hepatic origin) or embedded in surface tissues (dermal), and may possess an external lens, suggesting independent origins and multiple functions. Within Dendrobranchiata, we report bioluminescence in Sergestidae, Aristeidae, and Solenoceridae, and speculate that it may also be found in Acetidae, Luciferidae, Sicyonellidae, Benthesicymidae, and Penaeidae. Within Caridea, we report bioluminescence in Acanthephyridae, Oplophoridae, Pandalidae, and new observations for Pasiphaeidae. This comprehensive review includes historic taxonomic literature and recent studies investigating bioluminescence in all midwater and deep benthic shrimp families. Overall, we report known or suspected bioluminescence in 157 species across 12 families of decapod shrimps, increasing previous records of bioluminescent species by 65%. Mounting evidence from personal observations and the literature allow us to speculate the presence of light organs in several families thought to lack bioluminescence, making this phenomenon much more common than previously reported. We provide a detailed discussion of light organ morphology and function within each group and indicate future directions that will contribute to a better understanding of how deep‐sea decapods use the language of light. [ABSTRACT FROM AUTHOR]

The Norway lobster (Nephrops norvegicus) is one of the most important decapod crustacean seafood species in the Adriatic Sea. Previous research has identified significant differences in growth rates and maturation timing of Nephrops in the Pomo/Jabuka Pits area compared to other subpopulations in Adriatic fishing grounds. Here, we use 1,623 genome-wide single nucleotide polymorphisms (SNPs) to investigate whether the Pomo Pits subpopulation is genetically different from other sites in the Adriatic and neighbouring seas. We found no genetic differentiation among all sampled Adriatic sites, suggesting high gene flow between Pomo Pits Nephrops and those of surrounding areas. We also found genetic homogeneity between the Adriatic sites and single-site samples from the Aegean and Tyrrhenian Seas. However, we detected distinct genetic differentiation between all Mediterranean sites and an Atlantic site in western Scotland, which provides evidence for a phylogenetic break between the Atlantic and the Mediterranean. Our results indicate that Pomo Pits Nephrops are not genetically different from others sampled in the Adriatic and that key biological parameters in Pomo Pits Nephrops could be driven by spatial variation in fishing pressure and/or environmental factors rather than geographic isolation. [ABSTRACT FROM AUTHOR]

As a newly discovered virus, Decapoda iridovirus 1 (DIV1) can cause a mortality rate of up to 100% in crustaceans, leading to huge economic losses. At present, there is no effective prevention and control measures for this disease. In the present study, the specific primers targeting highly conserved regions of MCP gene were designed, and then a quantitative real-time PCR method was established. The results indicate that DIV1 quantitative real-time PCR established has good specificity and does not cross react with other pathogens including white spot syndrome virus (WSSV), infectious subcutaneous and hematopoietic necrosis virus (IHHNV) and Vibrio parahaemolyticus induced acute hepatopancreatic necrosis disease (VpAHPND). The real-time PCR was capable of detecting DIV1 DNA at a minimum concentration of 10 copies/µL within 34 cycles. The method has good repeatability, with intra group and inter group coefficients of variation both less than 2%. Thirty-two clinical samples were assessed using both the real-time PCR and conventional PCR. The results shown real-time PCR we established are more sensitive than conventional PCR. In conclusion, this method has strong specificity, stable repeatability, and high sensitivity, providing technical support for clinical diagnosis, epidemiology investigation and monitoring of DIV1. [ABSTRACT FROM AUTHOR]

Various biological traits support the invasive success of different organisms. The osmoregulatory capacity and food preferences of the signal crayfish Pacifastacus leniusculus were experimentally tested to determine if they contribute to its invasive success. The osmotic concentrations of haemolymph were determined after acclimation of the crustaceans to seven salinities from 0 to 20 PSU. Food preferences were tested using Canadian pondweed Elodea canadensis, and rainbow trout Oncorhynchus mykiss. The results showed that the signal crayfish exhibits a hyper-hypoosmotic regulation pattern in the salinity range from 0 to 20 PSU, enabling them to inhabit both freshwater and brackish environments. Furthermore, the study found signal crayfish to have non-specific food preferences, although fish muscle tissue is more beneficial as a source of energy. Both features, osmoregulatory ability and food preferences, can increase the invasive success of this species as it expands into new areas. The ability to survive in higher salinities compared to the coastal waters of the Baltic Sea along the Polish coastline should be considered in targeted management strategies to control the spread of this invasive species. [ABSTRACT FROM AUTHOR]

A study determining microsatellite markers was conducted to compare similarities among three different populations of Macrobrachium tenellum prawns from three different hydrological basins in Oaxaca, Mexico. In total, nine different markers in the population were used, of which six coded for the three populations and three did not. Although different, the three populations are closely genetically related, with an average allele richness from 6.845 to 16.754 and a heterozygosity of 0.166 to 0.264. However, the relationship could be much closer, particularly between them. The possible applications and scope of this knowledge are commented on and discussed. [ABSTRACT FROM AUTHOR]

We document the first record of Kishinouyepenaeopsis incisa (Wang & Liu in Liu & Wang, 1987) (Decapoda, Penaeidae) from the west coast of Peninsular Malaysia. Five specimens were initially collected during a trawling survey in April 2014, followed by another 17 specimens collected during sampling sessions from February 2023 to August 2023. Previously, this species was known to occur only in South China and Bangladesh. We provide detailed morphometric and meristic data, along with brief diagnostic characters, supported by genetic analysis that corroborates the species identity and distribution. [ABSTRACT FROM AUTHOR]

Grass shrimp of the genus Palaemon (Crustacea, Decapoda, Palaemonidae) occur worldwide in freshwater and saline wetlands. Palaemon species are frequently misidentified, and the genus itself has been reorganized several times. To clarify the intrageneric phylogenetic relationships and analyze the regional genetic diversity, we sequenced fragments of the mitochondrial cytochrome c oxidase subunit I (COI) and the nuclear Histone H3 (H3) genes from specimens collected along the northern Gulf of Mexico, where several morphologically similar Palaemon species reside. The generated sequences were combined with publicly available Palaemon sequences for phylogenetic and haplotype analyses. Our analyses indicate that the rostral formula is an unreliable character for species identification, that the Mississippi River does not act as a genetic barrier between the eastern and western populations, and that freshwater species are likely not derived from the saltwater species in the region. [ABSTRACT FROM AUTHOR]

Jack-knife shrimp Haliporoides sibogae is a target species for boat seine fishery in the waters off south-western Kyushu, Japan. Reproduction, including ovarian maturation, size at sexual maturity, and spawning season of this species were studied using females collected from Kagoshima Bay, southern Japan. The present study also explored an alternative maturity index by conducting a microscopic examination of oocytes. Histological analysis of the ovaries validated six oocyte developmental stages. Ovarian development was asynchronous, indicating multiple spawning throughout a reproductive season. On the basis of the developmental stage of the most advanced oocytes, ovarian maturity was categorized into three stages: immature, maturing and mature. Females containing oocytes exhibiting cortical crypts were defined as mature. The gonadosomatic index (GSI) significantly increased as ovarian maturation progressed, and all females with a GSI of ≥ 6% were determined to be mature. The minimum size at sexual maturity was estimated to be 24.0 mm in carapace length. The spawning season extended from November to May, with February being the peak. Moreover, microscopically, the oocytes with spherical bodies on the periphery all had cortical crypts. Therefore, observation of oocytes using a microscope was considered an effective method to easily identify mature females. [ABSTRACT FROM AUTHOR]

Some hosts harbor more parasites than others. Overdispersion of parasitism suggests that coevolution with parasites may be more important to the biology and ecology of certain species. We examined patterns of parasitism and host traits in fished decapod crustaceans, which are economically and ecologically important worldwide. Using a synthesis approach, we determine that host life history, including habitat, longevity, sociality, invasion history, and fisheries involvement, correlate with the number and type of parasite species harbored. Indicator species analysis revealed close relationships between decapods and certain parasite groups, including crabs with rhizocephalans and dinoflagellates; crayfish with mesomycetozoans, oomycetes, branchiobdellids, and fungi; lobsters with copepods and amoebae; and shrimp with viruses. In contrast, Nematomorpha and Nemertea appear to be under-represented and under-studied as parasite groups in decapods. Decapods that are commercially fished, aquacultured, introduced outside their native range, and/or exhibit parental care tend to have higher parasite species richness (PSR). Parasite richness also increases with how well-studied a host group is, which we addressed with a machine learning algorithm that predicts false negative associations. Geographic range is commonly positively correlated with parasite richness, however reliable ranges are not available for most decapod species, highlighting a significant future research need. Identifying patterns such as these increases our broad understanding of decapod disease ecology but also enabled us to develop a series of recommendations on how to focus future research, management, and aquaculture development efforts. [ABSTRACT FROM AUTHOR]

Genetic diversity is shaped by life history traits and environmental factors across the marine ecoregions of the world (MEOW), a condition that serves as a valuable framework to enhance our understanding of gene flow processes and identifying priority conservation centers among populations in different regions. We investigated the genetic and phylogenetic diversity of 13 decapod crustacean species distributed across the marine ecoregions of Brazil. We hypothesized that ecoregions act as barriers to gene flow, creating distinct population structures and varying genetic diversity levels. We examined how habitat type, bathymetry, geographical distribution, and larval development affect genetic diversity. Mitochondrial markers from 13 species of the four major decapod groups (Anomura, Brachyura, Caridea, and Penaeoidea) were analyzed using nucleotide diversity, haplotype networks, pairwise F ST, and linear mixed-effects models (LMER). Results show no significant genetic structuring among ecoregions. Genetic diversity correlates with habitat type (P < 0.05), with species from less impacted areas, especially intertidal zones like rocky shores and estuaries, displaying higher diversity. Phylogenetic diversity (PD) and species richness (SR) varied, with the highest PD in eastern Brazil and the highest SR in southeastern Brazil. Intertidal zones showed the highest genetic diversity, likely due to their complex microhabitats and environmental variability. Our findings indicate that environmental and geographical barriers defined by the ecoregions do not significantly impede genetic connectivity among decapod crustaceans, which suggests that high dispersal potential of larval stages facilitates genetic flow across ecoregions. The results underscore the need for conservation strategies that consider the high genetic connectivity and diversity of marine species across broad spatial scales. [ABSTRACT FROM AUTHOR]

Biological information on Glyphocrangon spinicauda A. Milne-Edwards, 1881, a western Atlantic deep-sea armored shrimp, is scant. This species occurs in the Gulf of Mexico, but at low abundance, in the southern (Mexican) part. We obtained a sample of 203 G. spinicauda at depths of 244–455 m during a research cruise exploring the biota of the upper continental slope of the southeastern Gulf of Mexico, off the Yucatán Peninsula. We examined morphometric and allometric relationships of the shrimp as well as some reproductive traits based on the number and size of embryos. Sex ratio (1.4 females:1 male) differed significantly from unity. Females had significantly larger total length (TL) and total weight, but not carapace length (CL), than males, suggesting that females have proportionally larger abdomens. All morphometric relationships were significant for both sexes and most were linear. Relationships against CL were mostly isometric, but TL and rostral length exhibited negative allometry, i.e. a proportionally smaller increase with increasing CL. Brood size (BS) and embryo mass volume were linearly related with female size, but embryo development stage significantly affected BS, embryo size, embryo mass volume, and reproductive output. We found a significant, negative relationship between residuals of the number and size of embryos, suggesting a trade-off in embryo production. Although G. spinicauda is of no commercial value, it co-occurs with other species of potential interest. Our results can thus be useful to design management and conservation plans should fisheries for deep-sea resources eventually develop in the southern Gulf of Mexico. [ABSTRACT FROM AUTHOR]

Nepinnotheres villosulus (Guérin-Méneville, 1832) [ Guérin-Méneville, 1829–1837 ] [type locality: Timor] and Nepinnotheres edwardsi (De Man, 1887) [type locality: Mergui Archipelago], as currently understood, are both reportedly widespread in Southeast Asia and northern Australia, and unique in the genus in having females densely covered by a setal tomentum that completely obscures the surfaces of the carapace and pereiopods. Based on the limited information contained in the type accounts, N. edwardsi and N. villosulus appear indistinguishable, but this cannot currently be confirmed by comparing type material because the holotype of N. villosulus , the senior name, is lost. A neotype is therefore designated for N. villosulus to fix its identity and taxonomic status as a senior synonym of N. edwardsi. In addition to the unique setation pattern of female N. villosulus , males of the species also present important differences from those of male Nepinnotheres sensu stricto. Pinnotheres trichopus Tesch, 1918 [type locality: Elat, Great Kei Island, Indonesia], is also shown to be a junior synonym of P. villosulus. Moreover, recent molecular phylogenetic analyses determined that N. villosulus is phylogenetically distant from Nepinnotheres sensu stricto. As such, we establish a new genus for N. villosulus. [ABSTRACT FROM AUTHOR]

The harvesting of the puerulus of rock, or spiny, lobsters for seed for aquaculture is a large industry throughout the Indo-Pacific region, and an increasing number of puerulus collectors are deployed. Little is known about the 'crowding effect' of the collectors and how catch might be influenced by their placement relative to each other owing to a lack of aggregate statistics for puerulus collectors in this region. The rock lobsters puerulus is also collected for fisheries research, as an index of puerulus catches on collectors can provide an indicator of recruitment strength. Both as a management tool and for commercial purposes, the collectors should act independently, not reducing or influencing catch rates on adjacent or other collectors in the area. We explored the independence of collectors of the puerulus of the southern rock lobster (Jasus edwardsii (Hutton, 1875)) using a long-term-data series from four sites on the east coast of Tasmania, Australia. Arrays of collectors were in grid and cross-shaped configurations, with individual collectors spaced three metres apart. Patterns in catches were examined using generalised least squares (GLS) modelling to determine if collectors filter pueruli as they swim shoreward, testing directional, neighbour, edge, and radial effects. The results revealed that there were no significant differences in puerulus settlement among collectors at this scale of spacing, meaning that arrays with collectors even as close as 3 m apart did not interfere with each other. This finding also suggests that collectors at this spacing only capture a small proportion of the available pueruli, allowing a significant number to pass through collector grids, with no significant reduction in catch of collectors further inshore. Such a result implies that it cannot be assumed that recruitment to a natural reef will be reduced by harvesting of pueruli with this type of collector and configuration. [ABSTRACT FROM AUTHOR]

Species of Plesionika Spence Bate, 1888 holds significant importance in the commercial harvesting of deep-sea shrimps along the southern coasts of India. Despite Plesionika quasigrandis Chace, 1985 being a crucial resource on the southwest coast of India, there is a need for comprehensive information on its food and feeding habits. We investigated the diet of P. quasigrandis in relation to sex, size, and season. The species exhibited a diet primarily consisting of crustaceans, foraminiferans, and detritus. Both males and females showed a noteworthy reliance on detritus, as indicated by an index of preponderance values exceeding 45.8. The species displayed active scavenging behaviour alongside predatory dietary habits. We observed a decrease in feeding intensity from pre-monsoon to post-monsoon in both males and females. Permutational multivariate analysis of variance (PERMANOVA) revealed significant differences in the diets of P. quasigrandis , considering the combined effects of size and sex (P < 0.01). No significant distinctions were noted in the diet composition between males and females in relation to season. [ABSTRACT FROM AUTHOR]

The corystid Gomeza serrata Dana, 1852, described from Patagonia in South America has rarely been reported and its taxonomy is poorly understood. While superficially similar to G. bicornis Gray, 1831 from the Indo-West Pacific and the type species of Gomeza Gray, 1931, direct comparisons have not been recorded. Examination of topotypic specimens show that Gomeza serrata is actually a juvenile of Peltarion spinosulus (White, 1843), a member of the family Trichopeltariidae. A neotype is selected for G. serrata to stabilize its taxonomy. [ABSTRACT FROM AUTHOR]

The present study aims to describe the histomorphology and ultrastructure of the hepatopancreas of a brachyuran crab, Varuna litterata using light and transmission electron microscopy. The hepatopancreas is an orange-yellow-coloured bilobed organ that comprises numerous blind-ended tubules. Each tubule is divided into proximal, mid, and distal regions and lined by pseudostratified epithelium with five cell types (E-, F-, R-, B-, M-cells). Each cell has distinct cytomorphological features and their relative percentages can vary along the length of the tubules. E-cells are embryonic cells and confined to the extreme distal end. It has a high nucleus-to-cytoplasm ratio and is involved in mitotic activity. M-cells are infrequently scattered throughout the length of the tubule without any brush border and play an important role in nutrient and endocrine regulation. R-cells exhibit a distinct polar organization of the cell organelles into apical, medial, and basal areas and are responsible for nutrient absorption, storage, and detoxification processes. F-cells contain abundant rER that gives fibrillar appearances to the cytoplasm and are involved in the synthesis of digestive enzymes. B-cells have an apical endocytotic complex in the early stage and a large central vacuole in the final stage of maturation. Mature B-cells are eliminated into the tubular lumen by holocrine secretion. These are considered for intracellular digestion and excretory functions. These findings provide the basic information regarding the identification, characterization, and functions of the hepatopancreatic cell types of V. litterata that might be useful in further nutritional research as well as in histopathological and biomarker studies. [ABSTRACT FROM AUTHOR]

The settlement phase is a challenging period for meropelagic octopus, as they adapt to their new life in the sea bottom after a planktonic period. Their ecology and trophic interactions with the surrounding fauna in the wild are practically unknown. To understand their predatory role in the littoral zone, the diet of recently settled Octopus vulgaris from a Mediterranean sandy bottom was studied through molecular methods. Amphipods were present in all the analysed stomach contents, with a total of 20 amphipod taxa recorded as prey. Jassa slatteryi and Microprotopus maculatus were the most commonly found amphipod species. Hydrozoans, decapod crustaceans, cephalopods and bivalves followed amphipods in importance. Niche breadth index assigned to small recently settled octopus the role of a specialised predator, increasing the diversity of prey as they grow. Larger juveniles displayed a higher number of prey taxa suggesting a decreasing predatory specialisation with octopus size and an ontogenetic shift in trophic ecology from diet mainly based on amphipods to a richer diet. The considerable arm elongation and the strong muscular arm crown development after settlement probably allow the juvenile benthic octopus to develop ambush predation and speculative hunting, increasing the range of potential benthic prey species along its adaptation to the benthos. [ABSTRACT FROM AUTHOR]

Freshwater crabs play essential roles in the well-functioning of the inland aquatic ecosystems. However, due to the lack of sufficient molecular resources, the study of freshwater crabs has been greatly hindered. In this study, the mitochondrial genome of Huananpotamon koatenense, a freshwater crab endemic to China, was sequenced for the first time. This mitogenome sequence is 15,528 bp long, and contains 13 protein-coding genes, 2 rRNA genes and 22 tRNA genes. Phylogenetic analyses based on 25 mitogenomes showed that H. koatenense was clustered with the known congeneric species of H. lichuanense.

Our study investigated the size at the onset of morphological sexual maturity, sexual size dimorphism, and relative growth in the green porcelain crab Petrolisthes armatus from a population in Northeastern Brazil. Specimens were collected monthly between February 2011 and January 2012 from the Baía do Pontal, Ilhéus, Bahia. We analysed 576 specimens, with females reaching the size at the onset of morphological sexual maturity at a carapace width of 4.7 mm and males at a carapace width of 5.83 mm. Sexual size dimorphism was confirmed, with females exhibiting a broader pleon and males a wider carapace and larger chelipeds. Positive allometry was observed in cheliped growth, with males exhibiting variation among juveniles and adults. Females showed ontogenetic distinctions in pleon width and cheliped dimensions. Our findings reveal that females and males of P. armatus exhibit different energetic investments in the development of secondary sexual characteristics, especially in cheliped growth for males and pleon enlargement for females. These results from a population of P. armatus in Northeastern Brazil contribute to a deeper understanding of reproductive strategies in females and males of the species. [ABSTRACT FROM AUTHOR]

In this study, the complex organization of the AnG in the giant freshwater prawn Macrobrachium rosenbergii was revealed using various techniques, including conventional histology, histochemistry, scanning electron microscopy, and X-ray tomography. The results showed the diversity of cells in the AnG and the detailed organization of the labyrinth's tubule into four radiated areas from the central to peripheral zones. The study also demonstrated the expression of some vertebrate kidney-associated homolog genes, aquaporin (AQP), solute carrier family 22 (SLC-22), nephrin, and uromodulin, in the AnG by qPCR. The result of in situ hybridization further showed the localization of SLC-22 and AQP transcript in the bladder and labyrinth's epithelium, specifically in regions 2, 3, and 4. Additionally, the study revealed neuropeptide expressions in the AnG by qPCR and in situ hybridization, i.e., crustacean hyperglycemic hormone (CHH) and molt inhibiting hormone (MIH), implying that the AnG may have a role in hormone production. Moreover, male and female prawns exhibited different levels of AQP, SLC-22, nephrin, and CHH expressions during the premolt and intermolt stages, suggesting a crucial role relevant to the molting stages. In conclusion, this study clarified the complex structure of the AnG in M. rosenbergii and demonstrated for the first time the expression of vertebrate kidney-associated genes and the possible endocrine role of the AnG. Further investigation is needed to clarify the role of these genes, particularly during ecdysis. The implications of these findings could significantly advance our understanding of the AnG in decapod crustaceans. [ABSTRACT FROM AUTHOR]

Land hermit crabs play a pivotal role in ecosystems as scavengers, contributing to the nutrient cycle in coastal forests and serving as a food source for various consumers. Nevertheless, they are subjected to large-scale capture for the pet trade in multiple regions. It is imperative to expand our knowledge of land hermit crabs to enhance conservation efforts. Taiwan is located in the transition zone between tropical and subtropical regions with rich biodiversity. Seven land hermit crab (Family: Coenobitidae) species have been identified here, namely Birgus latro, Coenobita brevimanus, C. cavipes, C. perlatus, C. purpureus, C. rugosus, and C. violascens. This article introduces the scientific record of the 8th species, Coenobita pseudorugosus, in Taiwan. Further ecological research of C. pseudorugosus is essential to deepen our understanding of this species and ensure its conservation status. [ABSTRACT FROM AUTHOR]

Simple Summary: This research investigated microplastic ingestion in two marine crustacean species of high commercial importance, namely the Giant Red Shrimp Aristaeomorpha foliacea and the Deep-Water Rose Shrimp Parapenaeus longirostris. The primary purpose of this study was to better understand how these species are affected by microplastic pollution, a growing concern in the marine environment worldwide. Based on stable isotope analysis of muscle tissue and on the examination of their gastrointestinal tracts, it was found that the trophic niche of the two species is similar, but the type of particles ingested differed significantly in terms of shape, colour, size class, and polymer. These outcomes shed light on the pervasive impact of microplastic contamination on marine wildlife, emphasising potential threats to consumers at higher levels of the food web. A better knowledge of pathways that microplastics follow through marine food webs is crucial for understanding the ecological implications posed by this emerging contaminant. Increasing plastic contamination poses a serious threat to marine organisms. Microplastics (MPs) ingestion can represent a risk for the organism itself and for the ultimate consumer. Through the analysis of the gastrointestinal tract, coupled with stable isotope analysis on the muscle tissue, this study provides insights into the relationship between MPs pollution and ecology in two commercial marine species caught in the Central Tyrrhenian Sea: Aristaeomorpha foliacea and Parapenaeus longirostris. Stable isotope analysis was conducted to determine the trophic position and the trophic niche width. The gastrointestinal tracts were processed, and the resultant MPs were analysed under FT-IR spectroscopy to estimate the occurrence, abundance, and typology of the ingested MPs. The trophic level of the species was similar (P. longirostris TP = 3 ± 0.10 and A. foliacea TP = 3.1 ± 0.08), with an important trophic niche overlap, where 38% and 52% of P. longirostris and A. foliacea has ingested MPs, respectively. Though species-level differences may not be evident regarding MP's abundance per individual, a high degree of dissimilarity was noted in the typologies of ingested particles. This research provides valuable insights into how MPs enter marine trophic webs, stressing that isotopic niche analysis should be combined with other methods to explain in detail the differences in MPs ingestion. [ABSTRACT FROM AUTHOR]

Little is known of the macrobenthos supported within stingray feeding pits. Compared to adjacent unpitted areas during low tide, macrobenthic abundance and biodiversity within the stingray pits might be expected to be (i) greater, the water-retaining pits functioning like rock pools; (ii) no different, since macrofaunal recolonisation can occur very rapidly; or (iii) less, consequent on the substratum changes that typify depressions in soft sediments. In both (i) and (iii) differences in composition of the supported assemblages would be expected, though not in (ii). To differentiate between these alternative hypotheses, faunal characteristics within intertidal stingray pits were compared to those in the adjacent background sandflat in Moreton Bay, Queensland, where the prey of the rays are the decapod crustaceans Trypaea and Mictyris that otherwise structure the benthic system. Results generally (though not totally) support hypothesis (ii), it being consistently found that feeding pits supported less macrobenthic abundance than the surrounding sandflat but subequal taxon density, evenness and patchiness of their faunas, and their taxonomic compositions were very similar. Such feeding pits undoubtedly structure many intertidal sandflats and increase both their topographical complexity and their habitat diversity, but this is not reflected in increased macrobenthic biodiversity. [ABSTRACT FROM AUTHOR]

The present work provides an updated and corrected list of hosts for the five European species of pinnotherid crabs, taking into consideration all recent published works as well as new data obtained in the present study. In relation to the number of hosts, there are two groups of species, one composed by Pinnotheres pisum and Afropinnotheres monodi with the highest number of hosts, and a second group, with a reduced number of hosts and more specific taxa, consisting of three other species: Nepinnotheres pinnotheres, Pinnotheres bicristatus, and P. pectunculi. When studying the relationships between host preferences, host distributions, and pea crab distributions, we could not find a clear direct relationship between these parameters. Temperature is also probably an important influence and relevant factor responsible for the distribution of pinnotherid crabs, and this may be independent from the potential distribution due to the distribution of hosts. [ABSTRACT FROM AUTHOR]

A single specimen of a new genus and species of marine palaemonid shrimp was collected from the outer slope of the barrier reef of Koumac, northwest New Caledonia. The new shrimp is remarkable due to its unique series of diagnostic characters, i.e., the presence of compressed supraorbital teeth, a well-developed orbital cavity, closely set antennal and hepatic teeth on the carapace, swollen eyestalks, fully reduced endites on the maxilla, an anteriorly produced lobe on the fourth thoracic sternite, relatively small second chelipeds, and strongly biunguiculate ambulatory dactyli. This specimen occupies an isolated phylogenetic position among the symbiotic palaemonid shrimp analyzed, only demonstrating a feeble morphological inclination towards the "gnathophyllid" section of these. However, neither the main diagnostic characters nor genetic data allow for further clarification of a closer relationship between this new shrimp and any currently known palaemonid genus as of yet. The new genus and species is described in this report, and its phylogenetic position is discussed based on molecular and morphological characters. [ABSTRACT FROM AUTHOR]

Freshwater crabs play essential roles in the well-functioning of the inland aquatic ecosystems. However, due to the lack of sufficient molecular resources, the study of freshwater crabs has been greatly hindered. In this study, the mitochondrial genome of Huananpotamon koatenense, a freshwater crab endemic to China, was sequenced for the first time. This mitogenome sequence is 15,528 bp long, and contains 13 protein-coding genes, 2 rRNA genes and 22 tRNA genes. Phylogenetic analyses based on 25 mitogenomes showed that H. koatenense was clustered with the known congeneric species of H. lichuanense. [ABSTRACT FROM AUTHOR]

In Brazil, glyphosate is present in more than 130 commercial formulations, and its toxic effects have already been tested in different species to understand its impact on biota Decapod crustaceans are widely used as experimental models due to their biology, sensitivity to pollutants, ease of collection, and maintenance under laboratory conditions. We evaluated the changes in metabolism (hemolymph) and oxidative balance markers (gill and hepatopancreas) of a crayfish (Parastacus promatensis) after exposure to Roundup® (active ingredient: glyphosate). The crayfish were captured in the Garapiá stream within the Center for Research and Conservation of Nature Pró-Mata, Brazil. We collected adult animals outside (fall) and during (spring) the breeding season. The animals were transported in buckets with cooled and aerated water from the collection site to the aquatic animal maintenance room at the university. After acclimatization, the animals were exposed to different concentrations of glyphosate (0, 65, 260, 520, and 780 µg/L). The results showed a significant variation in the hemolymph glucose, lactate, and protein levels. We observed variations in the tissue antioxidant enzymatic activity after exposure to glyphosate. Finally, the increase in oxidative damage required a high energy demand from the animals to maintain their fitness, which makes them more vulnerable to stress factors added to the habitat. [ABSTRACT FROM AUTHOR]

Crustaceans are one of the most widespread and speciose groups of marine organisms, fulfilling multiple ecological roles in numerous ecosystems. On coral reefs, many crustacean species form associations with scleractinian corals. Although the Red Sea is considered a biodiversity hotspot, few studies examined the diversity of coral-associated crustacean communities to date. In this study, 460 decapod crustaceans were recovered from 67 coral colonies of the three branching genera Acropora, Pocillopora and Stylophora in the central Saudi Arabian Red Sea. Crabs and shrimps were morphologically identified to the lowest taxonomic level possible, and portions of the mitochondrial COI and 16S rRNA genes were amplified with the objective of assessing their diversity and phylogenetic relationships. Finally, patterns of co-occurrence were evaluated to investigate the presence of species-specific symbiotic epifauna on different host corals. Overall, we recovered four families, five genera, and nine species of Red Sea crabs, nested into 11 molecular clades, and two families, eight genera and 11 species of shrimps, grouped within 12 lineages. Crabs of the species Trapezia tigrina were found to be exclusively associated with Pocillopora corals, while Tetralia crabs and the shrimps Jocaste japonica and Harpilius lutescens only occurred on Acropora colonies, providing evidence that potential loss of host corals due to local and global impacts could lead to consequent shifts in the symbiotic communities on reefs and to the loss of certain associated taxa. This study represents an advancement towards the understanding and molecular characterization of coral-associated benthic communities in the Red Sea and lays the ground for further research assessing the patterns of biodiversity, evolution, and ecological preferences of these organisms in the area. [ABSTRACT FROM AUTHOR]

The biology of extinct animals is usually reconstructed from external morphological characters and comparison with present-day analogues. Internal soft organs are very rarely preserved in fossils and require high-tech approaches for visualization. Here, we report the internal anatomy of a female and male of the ~ 162 Myr-old lobster Eryma ventrosum from the Jurassic La Voulte-sur-Rhône Konservat-Lagerstätte in France using X-ray synchrotron tomography. The Erymidae is an extinct, species-rich, widespread and ecologically important Mesozoic family of decapod crustaceans. Our investigation revealed the anatomy of the locomotory, respiratory, circulatory, excretory, digestive, nervous and sensory, and reproductive systems at a resolution resembling low-magnification histology. Particularly notable is the detailed preservation of the small brain and the fragile hepatopancreas, the main metabolic organ of decapods that decays rapidly post-mortem. The remarkable preservation shows that the internal anatomy of Eryma ventrosum is closer to that of Nephropidae (clawed lobsters) than Astacidae (freshwater crayfish), their closest living relatives based on skeletal morphology. The microanatomy of the gonads and hepatopancreas indicates that the two specimens investigated were a young, well-nourished female and male prior to sexual maturity. The analysis of the soft anatomy reveals remarkable conservatism over 160 Myr and offers new insights into feeding, reproduction, life history and lifestyle of an important component of the macrozoobenthos of Middle Jurassic seas. [ABSTRACT FROM AUTHOR]

The morphology of the zoeae I, II and III of Alpheus cf. packardii was described based on laboratory-hatched larvae. Parental female was captured at Ubatuba bay, north coast of São Paulo, Brazil. The morphological characteristics of the species were compared with descriptions of other Alpheus species with known first zoeal stages. The zoea I of A. cf. packardii differs from the other 27 species through: coxal endite of maxillule with 6 (4 simple, and 2 sparsely plumose) setae; basal endite with 2 stout spines, 1 small plumose setae and 1 small simple setae; coxal endite of maxilla not bilobed, with 2 long sparsely plumose setae; basal endite bilobed, proximal lobe 2 simple and 1 sparsely plumose setae, distal lobe with 2 simple setae and 1 sparsely plumose setae, both with one terminal protuberance; second maxilliped with endopod 4-segmented, 1 terminal simple, 0, 1 terminal serrate, 5 (1 proximal and 3 terminal simple, plus 1 terminal serrate) setae. Considering the importance of the identification of larval forms in the natural environment, our results can be used in a larval identification key and help to advance research on areas such as ecological distribution of early post-embryonic stages in the meroplankton community. [ABSTRACT FROM AUTHOR]

This study investigated the seasonal changes in embryonic development of the red snow crabs inhabiting the deep sea using wild and captive ovigerous females. The embryonic stages were categorised into 14 groups based on their external morphology. Females with recently spawned eggs (between stage 1 and early stage 3), those with the eggs at the midterm stage (mainly stages 7 and 8), and those with eggs just before hatching (stage 14) were observed simultaneously from January to March indicating a 2-year reproductive cycle. These findings aid in understanding and identifying the spawning years of the red snow crabs sampled from their natural habitats. [ABSTRACT FROM AUTHOR]

In the Sea of Japan, field studies have found snow crab and red snow crab larvae occur between the surface and depths of up to 550 m and 1100 m, respectively. In this region, snow crab larvae hatch at depths of 240–260 m and red snow crab larvae hatch at 1000–1500 m. To understand their vertical distribution during the larval period, we investigated the upward swimming speed of newly hatched larvae (first-stage zoea) and the behaviour of all larval stages (first and second zoeal and megalopal stages) in a temperature gradient under laboratory conditions. Our results showed that the larvae have the potential to reach the surface within a few days of hatching. As the larvae developed, they preferred greater depth and lower temperatures; although they temporarily rose to higher levels immediately after each moult. The zoeae and megalopae of both species did not occur beyond the 16 and 6°C temperature layers, respectively. The preferred position of the larvae in the gradient temperature did not differ between the two species. The present study suggests that Chionoecetes larvae transported to unsuitable temperatures may not die, but could escape from low temperatures by upward swimming and from high temperatures by sinking. [ABSTRACT FROM AUTHOR]

Limitations on energetic resources create evolutionary trade-offs, prompting us to investigate if investment in claw strength remains consistent across crustaceans living in diverse habitats. Decapod crustaceans living in deep-sea hydrothermal vents are ideal for this study due to their extreme environment. In this study, we investigated whether decapods (blind crab Austinograea sp. and the squat lobster Munidopsis lauensis) living in deep-sea hydrothermal vents prioritize investing in strong claws compared to the carapace, like coastal decapods. We analyzed exoskeleton morphology, mechanical properties, structures, and elemental composition in both the carapace and claws of four Decapoda species (two each from Brachyura and Anomura infraorders) in vent and coastal habitats. Coastal decapods had ∼4–9 times more teeth on their claw cutting edge than the vent species. Further, only the coastal species exhibited higher firmness in their claws than in their carapaces. Each infraorder controlled exoskeletal hardness differently: Brachyura changed the stacking height of the Bouligand structure, while Anomura regulated magnesium content in the exoskeleton. The vent decapods may prioritize strengthening their carapace over developing robust claws, allocating resources to adapt to the harsh conditions of deep-sea hydrothermal vents. This choice might enhance their survival in the extreme environment, where carapace strength is crucial for protecting internal organs from environmental factors, rather than relying on the powerful claws seen in coastal decapods for a competitive advantage. [ABSTRACT FROM AUTHOR]

In Indonesia, the sand crab Albunea symmysta distribution includes Java, Sumatra, and Moluccas. Populations are assumed to be differentiated between western and eastern Indonesia due to the Wallace line; however, no information on the genetic diversity and differentiation of A symmysta in Indonesia is available. This study was conducted to clarify the genetic diversity and differentiation of A. symmysta in Indonesia. During the sampling campaign, A. symmysta specimens were found only in Java and Papua. Genetic analysis based on the 643-bp fragment of the partial COI gene from 32 individuals revealed significant genetic differentiation between the Java and Papua populations (FST = 0.94, p < 0.005). The haplotype connectivity of the five A. symmysta sampling sites revealed a two-clade network. Based on analysis of molecular variance, most of the variation was found among populations (94.21%) rather than within populations (5.79%). Tajima's D and Fu's FS values indicated a population expansion. Overall, the findings support a high level of differentiation between the Java and Papua A. symmysta populations, suggesting the separation of population stocks due to low connectivity. [ABSTRACT FROM AUTHOR]

The autochthonous caramote prawn, Penaeus kerathurus, is highly exploited and widely studied throughout its distribution range in the Mediterranean. However, in Algeria, very few studies have been conducted on its biological aspects. In this research article, we provided for the first time a detailed analysis of the key parameters: length-weight relationships (LWRs) and condition factor (K) of prawns harvested from the unique coastal lagoon in the country, El Mellah Lake. Thus, the morphometric relationships between the total and carapace lengths against body weight were established for 1066 males, 608 females, and grouped individuals, revealing a negative allometric growth in all cases. Similarly, all K-obtained average values were less than the unit, indicating the poor nutritional status of prawns. Overall, the present findings showed that both parameters were sex-dependent and more likely reflect the population response to species growth and reproductive traits, biotic (new predator-prey relationship), and abiotic (lagoon’s meso-oligotrophic status) stimuli. The present study will be useful for better enhancing our understanding about P. kerathurus in southwestern Mediterranean and lagoon habitats. [ABSTRACT FROM AUTHOR]

In caridean shrimps, sexual systems vary from gonochorism to various forms of hermaphroditism. The shrimp Salmoneus carvachoi has been reported to exhibit both male (appendix masculina) and female (brooding embryos) anatomical characteristics simultaneously. Our aim was to examine the sexual system of S. carvachoi and to test the hypothesis of protandric simultaneous hermaphroditism (PSH) in this species. We analysed internal and external features using microscopy and histology techniques. Our analyses support the hypothesis of PSH in S. carvachoi and enabled the identification of male-phase and hermaphroditic individuals. All individuals exhibit a well-developed appendix masculina on the endopods of the second pleopods; however, small male-phase individuals possess only male gonopores, whereas larger hermaphroditic individuals possess both female and male gonopores. Hermaphrodites exhibit both male and female germinative cells in various stages of development, as well as an androgenic gland. Our study describes a novel sexual system for alpheids and provides a detailed description of anatomical traits in S. carvachoi. Studies that describe sexual systems in Alpheidae may shed light on the evolutionary history of gender expression in carideans and how environmental conditions favour sex allocation in decapods and other invertebrates. [ABSTRACT FROM AUTHOR]

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The study aims to identify the distribution and diversity of shrimp species (Decapoda) in the Babo, Bintun Mangrove Forest Area and its conservation aspects. This research has been carried out in the period from March 2024 to May 2024 in three villages in the waters of bintun Bay, Babo District, namely Nusei Village, Modan Village, and Amutu Village. The results of the analysis show that the number and abundance of shrimp at the three research stations in Babo are moderate. Only one species was found in the family Palaemonidae. The distribution of shrimp was influenced by the distribution of food. The average temperature of the shrimp was 25.06 °C, and the good temperature for the growth of white leg shrimp ranged from 22.0 - 29.6oC. The good temperature of shrimp ranges from 0 to 30oC. Among the six species, Penaeus indicus, jerbung, vannamei, and alpheus were the most abundant. [ABSTRACT FROM AUTHOR]

The alien Red Sea goatfish, Parupeneus forsskali (Fourmanoir & Guézé, 1976), is a Lessepsian migrant, entering the Mediterranean through the Suez Canal. This study explores its seasonal diet and biological traits in Cyprus, its non-native habitat. From August 2019 to July 2021, a total of 249 specimens were collected, ranging in total length (TL) from 5.8 to 27.7 cm, with a mean TL of 15.1 ± 4.54 cm (SD). These specimens were examined with respect to sex and season. Through various methods (F%, N%, W%, and IRI), the feeding habits of the species were analysed, revealing a diet dominated by Crustacea (mainly Decapoda) and Polychaeta, with the secondary consumption of Mollusca, Echinodermata, and others. Significant differences were found between males and juveniles and females and juveniles, with adults preferring Decapoda and juveniles Copepoda, while seasonal variations were mainly influenced by prey availability. The Red Sea goatfish exhibited ontogenetic niche shifts in its depth and habitat distribution, influenced by size and age. The trophic level (TROPH) of P. forsskali ranged from 3.22 to 3.46, corresponding to an omnivorous diet with a preference for animals. These findings suggest that P. forsskali is an opportunistic predator with a diverse diet, thriving in its new habitat and potentially impacting the local marine food webs by competing with economically important native species for resources. [ABSTRACT FROM AUTHOR]

Compound eyes formation in decapod crustaceans occurs after the nauplius stage. However, the key genes and regulatory mechanisms of compound eye development during crustacean embryonic development have not yet been clarified. In this study, RNA-seq was used to investigate the gene expression profiles of Neocaridina denticulata sinensis from nauplius to zoea stage. Based on RNA-seq data analysis, the phototransduction and insect hormone biosynthesis pathways were enriched, and molting-related neuropeptides were highly expressed. There was strong cell proliferation in the embryo prior to compound eye development. The formation of the visual system and the hormonal regulation of hatching were the dominant biological events during compound eye development. The functional analysis of DEGs across all four developmental stages showed that cuticle formation, muscle growth and the establishment of immune system occurred from nauplius to zoea stage. Key genes related to eye development were discovered, including those involved in the determination and differentiation of the eye field, eye-color formation, and visual signal transduction. In conclusion, the results increase the understanding of the molecular mechanism of eye formation in crustacean embryonic stage. [ABSTRACT FROM AUTHOR]

A new species of spider crab is described based on a single specimen collected from the Veraval fishing harbour, Gujarat, north-west coast of India, Arabian Sea. Globally nine species of spider crabs were reported of which four, Phalangipus filiformis , P. hystrix , P. indicus and P. longipes were documented from Indian waters. The new species, P. somnathensis sp. nov. differs from most species of the genus, based on the presence of blunt spines over the lateral & dorsal margin of the carapace, by the intestinal region being produced into a sharp spine, and by possessing a unique shape of male pleopod, i.e., branched into two lobes distally. The newly discovered species is compared with its congeners. [ABSTRACT FROM AUTHOR]

Phosphorus, calcium, and magnesium are pivotal elements in the exoskeleton of crustaceans, playing a crucial role in the moulting stages. As crustaceans cannot synthesize these nutrients, their acquisition relies on external sources, with tissues such as the hepatopancreas and gills actively participating in this process. Studying changes in phosphorus, calcium, and magnesium concentrations in these tissues is essential for a comprehensive understanding of their role in nutrient absorption during the moulting stages. The hepatopancreas, gills, muscles, and carapace of Macrobrachium nipponense (De Haan, 1849) were taken from the premoult, postmoult, and intermoult stages to study the changes in phosphorus, calcium and magnesium contents in the hepatopancreas, gills, muscles, and carapace during the moulting process of M. nipponense. Three parallel experiments were measured in each stage, and 10-20 prawns were mixed for each stage. Phosphorus content per tissue unit weight was measured using the vanadium-molybdenum yellow colorimetric method, and calcium and magnesium content per unit weight of tissue were measured using atomic absorption spectrophotometry. Phosphorus in the hepatopancreas and gills increased significantly from the premoult stage to the postmoult stage (P < 0.05), and magnesium also showed the same trend. Calcium in the hepatopancreas was significantly highest in the premoult phase, whereas phosphorus was significantly highest in the postmoult stage (P < 0.05). The hepatopancreas Ca/P ratio decreased significantly before and after moulting, while it increased significantly in the gills (P < 0.05). The results show that the hepatopancreas and gills are the main tissues that absorb phosphorus, calcium, and magnesium. The hepatopancreas absorbs and stores calcium earlier than phosphorus. The changes in the Ca/P ratio of the hepatopancreas and gills found that M. nipponense consumes more phosphorus than calcium during moulting and growth, and the gills have a better ability to absorb calcium than phosphorus. [ABSTRACT FROM AUTHOR]

This study explores the primary characteristics of intersexuality in Eriocheir sinensis in aquacultural environments. We employed a variety of research methods, including morphological observations, histological analysis, transcriptome analysis, and 3D reconstruction techniques, to comprehensively examine the phenomenon of intersexuality in this species. Our findings indicate that most intersex E. sinensis in aquaculture may be genetically female crabs undergoing masculinization processes. These crabs exhibit a combination of both external and internal sexual characteristics, with the extent of intersexuality varying among individuals. While these intersex crabs may engage in normal mating behaviour, the structures of their abnormal internal reproductive system may impede proper fertilization, ovulation, or egg production. Additionally, we found that the androgenic gland (AG) in intersex crabs did not inhibit ovarian development. Our study provides insights into the potential mechanisms underlying intersex occurrence in E. sinensis and contributes to the improvement of aquaculture practices, a reduction in the incidence of intersex crabs, and the safeguarding of consumer health. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of zinc (Zn)-supplemented diets on the growth, survival, and immunological indices of juvenile Pacific white shrimp, Penaeus vannamei. Four experimental diets were prepared and offered, which were: a non-supplemented basal diet (T1), a diet supplemented with organic Zn at 10 mg/kg (T2), a diet supplemented with organic Zn at 15 mg Zn/kg (T3), and a diet supplemented with inorganic Zn at 45 mg/kg (T4). In the 30-day feeding trial, specific growth rate, weight gain, and survival were significantly higher in shrimp fed T3 diets than in those fed T1 or T2. There were no significant differences in total haemocyte counts observed among the juvenile P. vannamei treated with Zn diets. In addition, dietary Zn supplementation significantly increased phagocytic activity of juvenile P. vannamei. Overall, these results indicate that appropriate dietary Zn has beneficial effects on growth, survival, and immune responses of juvenile Pacific white shrimp. [ABSTRACT FROM AUTHOR]