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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]

DNA barcoding is commonly used for species identification. Despite this, there has not been a comprehensive assessment of the utility of DNA barcoding in crayfishes (Decapoda: Astacidea). Here we examined the extent to which local barcoding gaps (used for species identification) and global barcoding gaps (used for species discovery) exist among crayfishes, and whether global gaps met a previously suggested 10× threshold (mean interspecific difference being 10× larger than mean intra specific difference). We examined barcoding gaps using publicly available mitochondrial COI sequence data from the National Center for Biotechnology Information's nucleotide database. We created two versions of the COI datasets used for downstream analyses: one focused on the number of unique haplotypes (NH) per species, and another that focused on total number of sequences (NS; i.e., including redundant haplotypes) per species. A total of 81 species were included, with 58 species and five genera from the family Cambaridae and 23 species from three genera from the family Parastacidae. Local barcoding gaps were present in only 30 species (20 Cambaridae and 10 Parastacidae species). We detected global barcoding gaps in only four genera (Cambarus, Cherax, Euastacus, and Tenuibranchiurus), which were all below (4.2× to 5.2×) the previously suggested 10× threshold. We propose that a ~5× threshold would be a more appropriate working hypothesis for species discovery. While the NH and NS datasets yielded largely similar results, there were some discrepant inferences. To understand why some species lacked a local barcoding gap, we performed species delimitation analyses for each genus using the NH dataset. These results suggest that current taxonomy in crayfishes may be inadequate for the majority of examined species, and that even species with local barcoding gaps present may be in need of taxonomic revisions. Currently, the utility of DNA barcoding for species identification and discovery in crayfish is quite limited, and caution should be exercised when mitochondrial‐based approaches are used in place of taxonomic expertise. Assessment of the evidence for local and global barcoding gaps is important for understanding the reliability of molecular species identification and discovery, but outcomes are dependent on the current state of taxonomy. As this improves (e.g., via resolving species complexes, possibly elevating some subspecies to the species‐level status, and redressing specimen misidentifications in natural history and other collections), so too will the utility of DNA barcoding. [ABSTRACT FROM AUTHOR]

Simple Summary: Injection of acetic acid into one leg of a crab caused rubbing of that leg and holding the leg off the floor of a tank. Such activities directed towards the site of a noxious stimulus are consistent with the idea of pain. Some crabs also cast off the leg injected with acid. Because that occurred in association with possible pain-related behaviour, it too might be caused by pain. Prior morphine injection caused various behavioural changes, but morphine did not ameliorate the responses to acetic acid. Therefore, morphine does not act as an analgesic, and this agrees with previous work. Nevertheless, the directed behaviour that follows injection into a leg agrees with other studies and provides additional evidence suggesting that these animals experience pain. Noxious chemicals, coupled with morphine treatment, are often used in studies on pain in vertebrates. Here we show that injection of morphine caused several behavioural changes in the crab, Carcinus maenas, including reduced pressing against the sides of the enclosure and more rubbing and picking at the mouth parts and, at least for a short time, more defensive displays. Subsequent injection of acetic acid into one rear leg caused rubbing of the injected leg and the injected leg was held vertically off the ground. These activities directed at or involving the specific leg are consistent with previous observations of directed behaviour following noxious stimuli and are consistent with the idea that decapods experience pain. Further, acetic acid but not injection of water induced autotomy of the injected leg in these animals. Because autotomy is temporally associated with directed behaviour, it is possible that the autotomy is a pain-related response. Acetic acid is clearly a noxious substance when applied to decapods. However, morphine had no effect on the activities associated with acetic acid injection and thus there is no evidence for an analgesic effect. Further, the injection of acetic acid did not interfere with behavioural effects of morphine. The activities directed towards the site of injection are like those observed with injection, or with external application, of various noxious substances and the present study adds to a growing body of knowledge about possible pain in decapods. [ABSTRACT FROM AUTHOR]

Organismal symbioses are fundamental to biodiversity, evolution, and ecosystem functioning. On coral reefs, many decapod species have formed distinct epibiotic symbioses through decoration tendencies that enhance diet, camouflage, and defence. The red decorator crab, Schizophrys aspera (Majidae: Decapoda), has a broad Indo-Pacific distribution and is a successful predator of juvenile crown-of-thorns seastars (CoTS; Acanthaster sp.). However, little is known of the biology and decorating symbioses of S. aspera on the Great Barrier Reef (GBR), where CoTS pose ongoing management challenges. We characterised S. aspera and its epibiont community collected in coral rubble patches on the southern GBR. S. aspera predominantly used sponges (94 ± 1%; mean ± SE) in its decoration, with greater proportions of the carapace covered for juveniles (58 ± 5%) and females (46 ± 4%) compared to males (24 ± 4%). In short-term (8-d) experiments, S. aspera substantially reduced sponge (31%) and algal (47%) cover on rubble pieces, demonstrating its potential to alter sessile communities. The close association of S. aspera with sponges and algae likely reflects its diet and enhances camouflage and chemical defence in its coral rubble niche on the GBR. As sessile taxa are often noxious, we postulate that these symbioses may confer resilience of S. aspera to plancitoxins in its consumption of CoTS. Evaluating how epibiont diversity and biochemistry shape the habitat associations, distribution, and role of S. aspera as predator and prey may be important to understanding its ability to mediate CoTS densities on the GBR and elsewhere. [ABSTRACT FROM AUTHOR]

Simple Summary: The idea that invertebrates feel pain is often dismissed because of claims that their responses to noxious stimuli are simply reflexes. Reflexes do not require higher-order processing, but that is required for pain experience. One way to test this claim is to ask if animals only respond to the noxious stimulus or if that response can be influenced by other motivations. Here, we report that shore crabs that enter a dark shelter from a light area and receive a shock are subsequently less likely to use that shelter if the light level is low and the shock level high. They trade their requirement to avoid bright light for the avoidance of the noxious shock. They learn to avoid the shelter and show signs of anxiety when deciding to enter the shelter to escape the light. These observations demonstrate that the responses to shock are not reflexes but are decisions that should improve the outcome better than a reflex alone. This balancing of needs is a key expectation of pain, and the results are consistent with the idea that crabs feel pain. The suggestion that decapod crustaceans might experience pain has been dismissed by some authors who claim decapods only respond to noxious stimuli by nociceptive reflexes. Because reflexes do not require complex neuronal processing, but pain does, demonstrating reflex responses to noxious stimuli would not support the case for pain. Here, we report an experiment in which shore crabs are repeatedly placed in a light area (20 trials), but the animals can avoid the light by moving to a dark shelter. However, some crabs received an electric shock of 6 or 12 volts each time they entered the shelter. Those receiving either level of shock swiftly reduced their use of shelters and remained in the light. However, the magnitude of shelter avoidance was influenced by the brightness of the arena and the intensity of the shock. Shelter use was subsequently reduced to a greater extent if the shock level was high and the light intensity low. That is, crabs traded their avoidance of shock for their avoidance of bright light. Further, these animals showed avoidance learning and demonstrated activities suggesting anxiety, such as contact with the tank wall in the light area and increased latency to enter shelters when making the decision to enter the shelter if they had received shock in earlier trials. These results fulfil three key behavioural criteria for pain and, thus, are consistent with the idea that decapods can experience pain. [ABSTRACT FROM AUTHOR]

Abstract DNA barcoding is commonly used for species identification. Despite this, there has not been a comprehensive assessment of the utility of DNA barcoding in crayfishes (Decapoda: Astacidea). Here we examined the extent to which local barcoding gaps (used for species identification) and global barcoding gaps (used for species discovery) exist among crayfishes, and whether global gaps met a previously suggested 10× threshold (mean interspecific difference being 10× larger than mean intra specific difference). We examined barcoding gaps using publicly available mitochondrial COI sequence data from the National Center for Biotechnology Information's nucleotide database. We created two versions of the COI datasets used for downstream analyses: one focused on the number of unique haplotypes (NH) per species, and another that focused on total number of sequences (NS; i.e., including redundant haplotypes) per species. A total of 81 species were included, with 58 species and five genera from the family Cambaridae and 23 species from three genera from the family Parastacidae. Local barcoding gaps were present in only 30 species (20 Cambaridae and 10 Parastacidae species). We detected global barcoding gaps in only four genera (Cambarus, Cherax, Euastacus, and Tenuibranchiurus), which were all below (4.2× to 5.2×) the previously suggested 10× threshold. We propose that a ~5× threshold would be a more appropriate working hypothesis for species discovery. While the NH and NS datasets yielded largely similar results, there were some discrepant inferences. To understand why some species lacked a local barcoding gap, we performed species delimitation analyses for each genus using the NH dataset. These results suggest that current taxonomy in crayfishes may be inadequate for the majority of examined species, and that even species with local barcoding gaps present may be in need of taxonomic revisions. Currently, the utility of DNA barcoding for species identification and discovery in crayfish is quite limited, and caution should be exercised when mitochondrial‐based approaches are used in place of taxonomic expertise. Assessment of the evidence for local and global barcoding gaps is important for understanding the reliability of molecular species identification and discovery, but outcomes are dependent on the current state of taxonomy. As this improves (e.g., via resolving species complexes, possibly elevating some subspecies to the species‐level status, and redressing specimen misidentifications in natural history and other collections), so too will the utility of DNA barcoding.

The nephropid lobster Hoploparia stokesi (Weller 1903a) is widely distributed among the islands of the Antarctic Peninsula, where it occurs in strata of Cretaceous (Campanian–Maastrichtian) to Palaeogene (Paleocene) age. Specimens of H. stokesi collected during expeditions in the 1980s that were in the collection of the United States Polar Rock Repository at The Ohio State University have been transferred to the Orton Geological Museum, joining other geological collections from Antarctica. Some of the transferred specimens are voucher specimens described or illustrated in earlier published work.

Personality variation, defined as among‐individual differences in behaviour that are repeatable across time and context, is widely reported across animal taxa. From an evolutionary perspective, characterising the amount and structure of this variation is useful since differences among individuals are the raw material for adaptive behavioural evolution. However, behavioural variation among individuals also has implications for more applied areas of evolution and ecology—from invasion biology to ecotoxicology and selective breeding in captive systems. Here, we investigate the structure of personality variation in the red cherry shrimp, Neocaridina heteropoda, a popular ornamental species that is readily kept and bred under laboratory conditions and is emerging as a decapod crustacean model across these fields, but for which basic biological, ecological and behavioural data are limited. Using two assays and a repeated measures approach, we quantify behaviours putatively indicative of shy–bold variation and test for sexual dimorphism and/or size‐dependent behaviours (as predicted by some state‐dependent models of personality). We find moderate‐to‐high behavioural repeatabilities in most traits. Although strong individual‐level correlations across behaviours are consistent with a major personality axis underlying these observed traits, the multivariate structure of personality variation does not fully match a priori expectations of a shy–bold axis. This may reflect our ecological naivety with respect to what really constitutes bolder, more risk‐prone, behaviour in this species. We find no evidence for sexual dimorphism and only weak support for size‐dependent behaviour. Our study contributes to the growing literature describing behavioural variation in aquatic invertebrates. Furthermore, it lays a foundation for further studies harnessing the potential of this emerging model system. In particular, this existing behavioural variation could be functionally linked to life‐history traits and invasive success and serve as a target of artificial selection or bioassays. It thus holds significant promise in applied research across ecotoxicology, aquaculture and invasion biology. [ABSTRACT FROM AUTHOR]

Simple Summary: The possibility of pain occurring in animals is often accepted if various criteria are fulfilled. These criteria include prolonged grooming or rubbing at the site of a wound or tissue damage, or other behaviour involving the site of damage. We also expect to see a reduction in such activities if a local anaesthetic is applied. Here, we report on an experiment that applied caustic soda, a known irritant in humans, to one eyestalk of the glass prawn. This caused immediate escape responses and then nipping and picking at the treated eyestalk rather than at the untreated eyestalk. Prior application of a local anaesthetic reduced the amount of directed behaviour. However, the local anaesthetic also appeared to be an irritant as it too caused immediate escape responses and directed behaviour to the eyestalk. The results provide further support to the idea that these animals can experience pain. Acceptance of the possibility of pain in animals usually requires that various criteria are fulfilled. One such criterion is that a noxious stimulus or wound would elicit directed rubbing or grooming at the site of the stimulus. There is also an expectation that local anaesthetics would reduce these responses to damage. These expectations have been fulfilled in decapod crustaceans but there has been criticism of a lack of replication. Here, we report an experiment on the effects of a noxious chemical, sodium hydroxide, applied to one eyestalk of the glass prawn. This caused an immediate escape tail-flick response. It then caused nipping and picking with the chelipeds at the treated eyestalk but much less so at the alternative eyestalk. Prior treatment with benzocaine also caused an immediate tail-flick and directed behaviour, suggesting that this agent is aversive. Subsequently, however, it reduced the directed behaviour caused by caustic soda. We thus demonstrated responses that are consistent with the idea of pain in decapod crustaceans. [ABSTRACT FROM AUTHOR]

Decapod crustaceans are important components of the fauna of soft-bottom habitats. In this work, the records of decapod crustaceans are provided through the analysis of a large soft-bottom benthic macroinvertebrates dataset of the Central Mediterranean Sea. Decapod crustacean assemblages were collected in the last twenty years by a Van Veen grab in 42 study sites located along the Italian coasts at depths ranging from 1 up to 120 m. The spatial distribution of the crustaceans examined, which include 120 species belonging to 40 families, was investigated according to the biogeographical zones identified in the Italian seas. The spatial distribution of 36 species was updated, comparing the ISPRA decapod crustacean dataset with the most recent Italian checklists. For the species updated, the number of specimens, the year and season of sampling, and environmental data, such as the bathymetric range and habitat details, are provided for each site investigated. Data are discussed and compared with the existing literature, also referring to what is reported in the World Register of Marine Species (WoRMS), with the aim of contributing to the knowledge of the biodiversity of the marine species and supporting the updating of checklists and registers in the Mediterranean Basin. [ABSTRACT FROM AUTHOR]

Noxious chemicals, coupled with morphine treatment, are often used in studies on pain in vertebrates. Here we show that injection of morphine caused several behavioural changes in the crab, Carcinus maenas, including reduced pressing against the sides of the enclosure and more rubbing and picking at the mouth parts and, at least for a short time, more defensive displays. Subsequent injection of acetic acid into one rear leg caused rubbing of the injected leg and the injected leg was held vertically off the ground. These activities directed at or involving the specific leg are consistent with previous observations of directed behaviour following noxious stimuli and are consistent with the idea that decapods experience pain. Further, acetic acid but not injection of water induced autotomy of the injected leg in these animals. Because autotomy is temporally associated with directed behaviour, it is possible that the autotomy is a pain-related response. Acetic acid is clearly a noxious substance when applied to decapods. However, morphine had no effect on the activities associated with acetic acid injection and thus there is no evidence for an analgesic effect. Further, the injection of acetic acid did not interfere with behavioural effects of morphine. The activities directed towards the site of injection are like those observed with injection, or with external application, of various noxious substances and the present study adds to a growing body of knowledge about possible pain in decapods.

Abstract Personality variation, defined as among‐individual differences in behaviour that are repeatable across time and context, is widely reported across animal taxa. From an evolutionary perspective, characterising the amount and structure of this variation is useful since differences among individuals are the raw material for adaptive behavioural evolution. However, behavioural variation among individuals also has implications for more applied areas of evolution and ecology—from invasion biology to ecotoxicology and selective breeding in captive systems. Here, we investigate the structure of personality variation in the red cherry shrimp, Neocaridina heteropoda, a popular ornamental species that is readily kept and bred under laboratory conditions and is emerging as a decapod crustacean model across these fields, but for which basic biological, ecological and behavioural data are limited. Using two assays and a repeated measures approach, we quantify behaviours putatively indicative of shy–bold variation and test for sexual dimorphism and/or size‐dependent behaviours (as predicted by some state‐dependent models of personality). We find moderate‐to‐high behavioural repeatabilities in most traits. Although strong individual‐level correlations across behaviours are consistent with a major personality axis underlying these observed traits, the multivariate structure of personality variation does not fully match a priori expectations of a shy–bold axis. This may reflect our ecological naivety with respect to what really constitutes bolder, more risk‐prone, behaviour in this species. We find no evidence for sexual dimorphism and only weak support for size‐dependent behaviour. Our study contributes to the growing literature describing behavioural variation in aquatic invertebrates. Furthermore, it lays a foundation for further studies harnessing the potential of this emerging model system. In particular, this existing behavioural variation could be functionally linked to life‐history traits and invasive success and serve as a target of artificial selection or bioassays. It thus holds significant promise in applied research across ecotoxicology, aquaculture and invasion biology.

Cryptic species and their interactions are challenging to describe owing to the difficulties in observing and sampling their populations. Such methodological hurdles are critical to resolve, especially when important interactions involving poorly described species are detected. The red decorator crab, Schizophrys aspera , is a newfound predator of the corallivorous Pacific crown-of-thorns seastar (CoTS; Acanthaster sp.). We discuss the Indo-Pacific distribution and taxonomy of S. aspera and provide characterization of its cryptic population at sites around Heron Island, Great Barrier Reef, that differ in CoTS densities. Most S. aspera (>95%) were found under coral rubble pieces atop existing rubble, associated with large pieces and chasmic interstices. The three smallest individuals (carapace width: 5–11 mm) were found under rubble overlying sand. Mean density of S. aspera was 0.8 ± 0.2 ind. 100 m−2, which varied among sites. Areas with lower records of CoTS had higher densities of S. aspera (p  = 0.002; R 2 = 0.25), which justifies evaluation of the distribution and impact of this species in context of CoTS outbreaks. We present a method to survey cryptic decapods on coral reefs, along with microhabitat characteristics to help predict S. aspera on reefs prone to CoTS outbreaks and its capacity to act as a natural top-down control mechanism. [ABSTRACT FROM AUTHOR]

In decapod crustaceans, the conditions experienced during embryonic development trigger phenotypic plasticity of the larvae at hatching. The objective of this study was to test the effects of temperature during embryonic development of Palaemon serratus on the phenotypic plasticity of hatching larvae. We incubated egg‐bearing females from eggs laying to hatching at four temperatures (10, 15, 18 and 20°C). Weight, carbon and nitrogen contents were measured on newly laid eggs and on freshly hatched larvae. The duration of embryonic development was negatively correlated with incubation temperature. At 20°C, all females abandoned their eggs during development. Incubation temperature had no effect on the weight and the percentage of N of the larvae at hatching, while it did affect their percentage of C and their C/N ratio. Embryos incubated at 10°C seemed to produce larvae with fewer lipid reserves than those incubated at 15 and 18°C. They probably overconsumed their lipid reserves to compensate for the metabolic losses due to the low temperature. These results provide information on the link between maternal investment per egg and larval development in P. serratus. [ABSTRACT FROM AUTHOR]

Assessing decapod sensitivity to regional-scale ocean acidification (OA) conditions is limited because of a fragmented understanding of the thresholds at which they exhibit biological response. To address this need, we undertook a three-step data synthesis: first, we compiled a dataset composed of 27,000 datapoints from 55 studies of decapod responses to OA. Second, we used statistical threshold analyses to identify OA thresholds using pH as a proxy for 13 response pathways from physiology to behavior, growth, development and survival. Third, we worked with the panel of experts to review these thresholds, considering the contributing datasets based on quality of the study, and assign a final thresholds and associated confidence scores based on quality and consistency of findings among studies. The duration-dependent thresholds were within a pH range from 7.40 to 7.80, ranging from behavioral and physiological responses to mortality, with many of the thresholds being assigned medium-to-high confidence. Organism sensitivity increased with the duration of exposure but was not linked to a specific life-stage. The thresholds that emerge from our analyses provide the foundation for consistent interpretation of OA monitoring data or numerical ocean model simulations to support climate change marine vulnerability assessments and evaluation of ocean management strategies.

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The suggestion that decapod crustaceans might experience pain has been dismissed by some authors who claim decapods only respond to noxious stimuli by nociceptive reflexes. Because reflexes do not require complex neuronal processing, but pain does, demonstrating reflex responses to noxious stimuli would not support the case for pain. Here, we report an experiment in which shore crabs are repeatedly placed in a light area (20 trials), but the animals can avoid the light by moving to a dark shelter. However, some crabs received an electric shock of 6 or 12 volts each time they entered the shelter. Those receiving either level of shock swiftly reduced their use of shelters and remained in the light. However, the magnitude of shelter avoidance was influenced by the brightness of the arena and the intensity of the shock. Shelter use was subsequently reduced to a greater extent if the shock level was high and the light intensity low. That is, crabs traded their avoidance of shock for their avoidance of bright light. Further, these animals showed avoidance learning and demonstrated activities suggesting anxiety, such as contact with the tank wall in the light area and increased latency to enter shelters when making the decision to enter the shelter if they had received shock in earlier trials. These results fulfil three key behavioural criteria for pain and, thus, are consistent with the idea that decapods can experience pain.

Acceptance of the possibility of pain in animals usually requires that various criteria are fulfilled. One such criterion is that a noxious stimulus or wound would elicit directed rubbing or grooming at the site of the stimulus. There is also an expectation that local anaesthetics would reduce these responses to damage. These expectations have been fulfilled in decapod crustaceans but there has been criticism of a lack of replication. Here, we report an experiment on the effects of a noxious chemical, sodium hydroxide, applied to one eyestalk of the glass prawn. This caused an immediate escape tail-flick response. It then caused nipping and picking with the chelipeds at the treated eyestalk but much less so at the alternative eyestalk. Prior treatment with benzocaine also caused an immediate tail-flick and directed behaviour, suggesting that this agent is aversive. Subsequently, however, it reduced the directed behaviour caused by caustic soda. We thus demonstrated responses that are consistent with the idea of pain in decapod crustaceans.

Decapod crustaceans are important components of the fauna of soft-bottom habitats. In this work, the records of decapod crustaceans are provided through the analysis of a large soft-bottom benthic macroinvertebrates dataset of the Central Mediterranean Sea. Decapod crustacean assemblages were collected in the last twenty years by a Van Veen grab in 42 study sites located along the Italian coasts at depths ranging from 1 up to 120 m. The spatial distribution of the crustaceans examined, which include 120 species belonging to 40 families, was investigated according to the biogeographical zones identified in the Italian seas. The spatial distribution of 36 species was updated, comparing the ISPRA decapod crustacean dataset with the most recent Italian checklists. For the species updated, the number of specimens, the year and season of sampling, and environmental data, such as the bathymetric range and habitat details, are provided for each site investigated. Data are discussed and compared with the existing literature, also referring to what is reported in the World Register of Marine Species (WoRMS), with the aim of contributing to the knowledge of the biodiversity of the marine species and supporting the updating of checklists and registers in the Mediterranean Basin.

Decapods have been recently classified as sentient beings in UK policy and therefore the establishment of humane methods for the live transportation and slaughter of commercially valuable shellfish as well as for decapods used in research is critical. Formerly overlooked, the use of anaesthetics provides a promising avenue for improving welfare standards for husbandry and slaughter for decapod crustaceans destined for human consumption or research. In particular, clove oil and its derivatives (eugenol and isoeugenol) have been trialled and recommended in literature as naturally-derived and effective, reversible anaesthetic compounds for a variety of decapods, including two commercially important British shellfish, brown crab (Cancer pagurus) and Norway lobster (Nephrops norvegicus). Further investigations should be undertaken to confirm the use of such anaesthetics is suitable for improving welfare standards in the British shellfish sector and in research to ensure that when the legislation changes, humane solutions are present.

IntroductionGenetic variation underlies the populations’ potential to adapt to and persist in a changing environment, while phenotypic plasticity can play a key role in buffering the negative impacts of such change at the individual level.MethodsWe investigated the role of genetic variation in the thermal response of the northern shrimp Pandalus borealis, an ectotherm species distributed in the Arctic and North Atlantic Oceans. More specifically, we estimated the proportion transcriptomic responses explained by genetic variance of female shrimp from three origins after 30 days of exposure to three temperature treatments.ResultsWe characterized the P. borealis transcriptome (170,377 transcripts, of which 27.48% were functionally annotated) and then detected a total of 1,607 and 907 differentially expressed transcripts between temperatures and origins, respectively. Shrimp from different origins displayed high but similar level of transcriptomic plasticity in response to elevated temperatures. Differences in transcript expression among origins were not correlated to population genetic differentiation or diversity but to environmental conditions at origin during sampling.DiscussionThe lack of genetic variation explaining thermal plasticity suggests limited adaptability in this species’ response to future environmental changes. These results together with higher mortality observed at the highest temperature indicate that the thermal niche of P. borealis will likely be restricted to higher latitudes in the future. This prediction concurs with current decreases in abundance observed at the southern edge of this species geographical distribution, as it is for other cold-adapted crustaceans.

In crustaceans that live in seasonal environments and produce several broods during an annual cycle, there are generally seasonal patterns in reproductive traits. Thus, females are able to modulate the trade-off between per offspring investment and quantity of eggs produced in order to maximise the fitness of their offspring in response to the environmental conditions they will face during their development. We collected females of Palaemon serratus (Pennant, 1777) that had just laid eggs during the entire laying season from December 2021 to November 2022 on the coast of Seine-Maritime (France). We measured their fecundity, biomass per egg and the fatty acid composition of the eggs. The largest females laid their eggs from December to March ("winter laying") and from May to July ("summer laying"), while the smallest females laid from January to August. Fecundity and in general biomass per egg increased with the size of the females. The FA concentration of eggs decreased throughout the laying season and winter eggs were more concentrated in essential PUFAs than summer eggs. In summer, the old females laid eggs with the same biomass as those laid by the young females, enabling them to significantly increase their relative fecundity. All these trends are consistent with the environmental conditions encountered by future embryos and larvae. These results provide a clear illustration of the maternal effects and trade-offs between reproductive traits observed in decapods. • Palaemon serratus females live for 2 to 5 years and lay eggs twice a year (winter and summer layings). • We measured the fecundity, egg biomass and fatty acid content of broods from December to August. • In winter, fecundity, biomass per egg and FA content increase with the age of the females. • In summer, old females produce eggs identical to those of young females, but in very large numbers. • Fitness is maximised by adapting the investment per offspring to anticipated seasonal conditions. [ABSTRACT FROM AUTHOR]

Simple Summary: Decapod crustaceans are used extensively in laboratory experiments. Recently in the United Kingdom decapods have been included in animal care protocols. However, little is known about how captive conditions affect the survival and general condition of wild crustaceans. We used the green shore crab, Carcinus maenas, to investigate the effects of stocking density and shelter on survival and vitality indices during a 6 month period in the laboratory. Both stocking density and the presence of shelter did not affect survival, nor have a clear effect on vitality indices (limb loss, claw strength, 'blood' protein concentration, righting time, leg flare and retraction). However, vitality indices showed that crab condition was declining over time: this became most apparent after 8 to 11 weeks storage in the laboratory. This decline in condition was likely due to repeated handling of the crabs, rather than the stocking conditions, which apparently led to a cumulative stress and a deterioration in animal health. Bringing wild crustaceans into the laboratory and holding them, even with modest experimental manipulation, may result in high mortality rates. Researchers and animal care committees need to be aware that wild captive invertebrates will respond very differently to laboratory-bred vertebrates, and plan experiments accordingly. The wide geographic distribution, large size and ease of capture has led to decapod crustaceans being used extensively in laboratory experiments. Recently in the United Kingdom decapod crustaceans were listed as sentient beings, resulting in their inclusion in animal care protocols. Ironically, little is known about how captive conditions affect the survival and general condition of wild decapod crustaceans. We used the green shore crab, Carcinus maenas, to investigate the effects of stocking density and shelter on survival and vitality indices during a 6 month period in the laboratory. Neither stocking density nor the presence of shelter affected survival. Stocking density also had no effect on the vitality indices (limb loss, claw strength, BRIX, righting time, leg flare and retraction). The presence of shelter did affect the number of limbs lost and the leg retraction response, but had no effect on the other vitality indices. All vitality indices changed, and mortality increased over time, independent of treatment: this became most apparent after 8 to 11 weeks storage in the laboratory. This decline in condition may have been due to repeated handling of the crabs, rather than the stocking conditions. In support of this, untracked, non-handled (control) individuals sustained a 4% mortality rate compared with 67% mortality in experimental crabs during the 6 month period. Although simple experimental monitoring of crabs with biweekly vitality tests only produced transient short-term stress events, the repeated handling over time apparently led to a cumulative stress and a deterioration in animal health. Bringing wild crustaceans into the laboratory and holding them, even with modest experimental manipulation, may result in high mortality rates. Researchers and animal care committees need to be aware that wild captive invertebrates will respond very differently to laboratory-bred vertebrates, and plan experiments accordingly. [ABSTRACT FROM AUTHOR]

The toxicity of pesticides to non-target organisms continues to be important in understanding the dynamic interactions between anthropogenic chemicals and ecosystem health. This study assesses biochemical markers to determine the effects that varying concentrations of atrazine (13.1–5557 µg/l) have on the freshwater shrimp, Caridina africana. Exposure and oxidative stress biomarkers were analysed and followed by univariate, integrated biomarker response v2 (IBRv2) and Kendall Tau correlation statistical analyses, to gain insight into the concentration-dependent responses. Oxidative stress biomarkers such as reduced glutathione content (GSH), glutathione-S-transferase activity (GST), superoxide dismutase activity (SOD) and catalase activity (CAT) were significantly correlated with increasing atrazine exposure concentration (p < 0.01). Bimodality has been seen when looking at both the univariate statistically significant differences as well as the IBRv2, with the first peak at 106.8 µg/l and the second peak at 5557 µg/l atrazine. The results indicate that while individual responses may indicate statistically significant differences, using correlation and integrated statistical analysis can shed light on trends in the adaptive response of these. [ABSTRACT FROM AUTHOR]

Decapod iridescent virus 1 (DIV1) is an emerging viral pathogen that seriously threatens crustacean farming and has caused enormous economic losses in recent years. This virus was originally isolated and identified from diseased crayfish Cherax quadricarinatus and shrimp Litopenaeus vannamei in Fujian and Zhejiang, China, in 2014 by two research groups. In 2019, the Executive Committee of the International Committee on Taxonomy of Viruses approved DIV1 as a member of the new genus Decapodiridovirus in the family Iridoviridae. DIV1 is icosahedral in shape and contains a single linear double‐stranded DNA genome of approximately 165 kb. DIV1 can infect many host species, including freshwater and seawater crustaceans, but infected hosts do not show unique pre‐clinical signs, which increases the difficulties in the diagnosis and treatment of this disease. Increasing progress has been made towards understanding many aspects of this virus, including its classification, genomic features, transmission mode, host range, pathogenicity, clinical symptoms, histopathology, detection method and host immunity in response to infection. In this review, we provide an overview of recent progress towards understanding the epidemiology and pathobiology of disease caused by DIV1 and highlight the future research prospects in control and prevention strategies. [ABSTRACT FROM AUTHOR]

Simple Summary: Policies that affect animals need to consider which animals can experience suffering and other positive or negative feelings. Policymakers, therefore, need to determine which animals should be treated as sentient. This requires answering several questions about the definition, criteria, evidence requirements and sources, and how far the conclusions should be generalized. These should use scientific evidence where available, but the process is also full of ethical aspects that should conform to ethical principles applicable to policymakers, such as selflessness, objectivity, accountability and openness. Deciding which animals are sentient is an important precursor for decisions about the application of animal welfare legislation, and the wider assessment of the impacts of policies on animal suffering. We ascribe sentience in order to inform decisions about how animals should be treated, and how their treatment should be regulated. This ascription is both an ethical and an evidential process, and what evidence to use and require are ethical questions. Policymakers, therefore, cannot simply rely on scientific evidence in an ethically neutral way, but must be conscious of the ethical assumptions and positions underlying the process of ascription and its application in policy and law. As such, ethical principles that apply to policymaking apply to the ascription of sentience. This paper considers the implications of the Nolan principles for public service on the ascription of animals. [ABSTRACT FROM AUTHOR]

Climate change combined with anthropogenic stressors (e.g. overfishing, habitat destruction) may have particularly strong effects on threatened populations of coastal invertebrates. The collapse of the population of European lobster (Homarus gammarus) around Helgoland constitutes a good example and prompted a large-scale restocking program. The question arises if recruitment of remaining natural individuals and program-released specimens could be stunted by ongoing climate change. We examined the joint effect of ocean warming and acidification on survival, development, morphology, energy metabolism and enzymatic antioxidant activity of the larval stages of the European lobster. Larvae from four independent hatches were reared from stage I to III under a gradient of 10 seawater temperatures (13–24°C) combined with moderate (∼470 µatm) and elevated (∼1160 µatm) seawater pCO2 treatments. Those treatments correspond to the shared socio-economic pathways (SSP), SSP1-2.6 and SSP5-8.5 (i.e. the low and the very high greenhouse gas emissions respectively) projected for 2100 by the Intergovernmental Panel on Climate Change. Larvae under the elevated pCO2 treatment had not only lower survival rates, but also significantly smaller rostrum length. However, temperature was the main driver of energy demands with increased oxygen consumption rates and elemental C:N ratio towards warmer temperatures, with a reducing effect on development time. Using this large temperature gradient, we provide a more precise insight on the aerobic thermal window trade-offs of lobster larvae and whether exposure to the worst hypercapnia scenario may narrow it. This may have repercussions on the recruitment of the remaining natural and program-released specimens and thus, in the enhancement success of future lobster stocks. [ABSTRACT FROM AUTHOR]

Simple Summary: The use of decapods (such as lobsters and crabs) and cephalopods (such as octopuses and cuttlefish) by humans for food, experimentation and education (e.g., in zoos and aquariums) is on the increase. Growing evidence that these species have feelings and can experience emotions has highlighted the need for a tool to monitor the welfare of these species in captivity. This study adapted a welfare monitoring tool, the Animal Welfare Assessment Grid, that has been successfully used with a variety of mammal and bird species, for use with decapods and cephalopods. This tool was then trialed at a zoological institution (Marwell Zoo, UK) and, for the first time, a public aquarium (National Marine Aquarium, UK), with the intention of showing how data collected on invertebrates in a zoological environment can be both efficiently and easily applied to implement positive welfare. This study highlights how evaluating the welfare impact of management processes using animal-based indicators can lead to improved welfare outcomes. Consumer demand for invertebrates is on the rise as their numbers in the wild dwindle. However, with the growing conservation efforts of modern zoos and aquariums, and evidence from over 300 studies showing that invertebrates are capable of sentience, public interest, and moral concern for welfare of invertebrates have increased. The challenge for zoos and aquariums is in developing an objective and repeatable method for evaluating welfare that can be applied to invertebrates in zoological collections. Recently introduced into zoological collection management is the Animal Welfare Assessment Grid (AWAG). The AWAG helps to identify negative and positive welfare states, through assessing animal- and environmental-based indicators to make changes that lead to a better quality of life. Originally developed for the assessment of laboratory primates, the system has been successfully adapted to assess a variety of taxa across different environments, facilitated by the development of cloud-based software. In this study, the AWAG has been adapted to assess the cumulative lifetime experience of captive decapods and cephalopods at two different institutions, Marwell Zoo and National Marine Aquarium. This study has provided further evidence that the AWAG is adaptable and demonstrates the first time any objective scoring system has been successfully adapted for use in invertebrates. Through graphical representation, the results show that the AWAG identifies changes in welfare scores that can be attributed to specific events and can be used to predict the future vulnerability of species to welfare changes and suggest alternative management methods. This monitoring tool provides a versatile method of implementing practical welfare monitoring in zoos and aquariums. [ABSTRACT FROM AUTHOR]

Surveying free-ranging crab populations is important for monitoring the health of exploited stocks and predicting future productivity. Here, we present a novel research trap design for use in fisheries-independent surveys of blue swimmer crab (Portunus armatus) populations, and evaluate the trap against some existing approaches within an independent survey framework. Specifically, the trap design aimed to improve efficiency for capturing smaller crabs, without adversely affecting catches of larger crabs. We quantify and report the abundance and selectivity of these traps, relative to co-located samples obtained using beam trawls and standard commercial round traps, to establish whether these small-mesh traps may offer any improvements over existing survey methods. Comparison and evaluation of these small-mesh traps against other existing survey gear, in different places and at different times, showed that the traps are more effective at catching smaller crabs when they are present, and equally or more effective at catching larger size classes of crabs. The beam trawl appeared to be effective at capturing a reasonable size range of crabs; however, the number of crabs caught (using a similar investment of time) was substantially lower than that caught in traps. This novel small-mesh research trap appears suitable for fisheries-independent surveys of portunid crab species. This manuscript presents an evaluation of a novel crab trap for use in fisheries-independent surveys, and evaluates the efficacy of this trap against existing approaches within an independent survey framework. We quantify and report the abundance, variability and size structure of these traps relative to co-located samples obtained using beams trawls and standard round crab traps, to establish whether these traps may offer any improvements over existing survey methods. [ABSTRACT FROM AUTHOR]

Spiny lobsters rely on multiple biomineralized exoskeletal predator defenses that may be sensitive to ocean acidification (OA). Compromised mechanical integrity of these defensive structures may tilt predator-prey outcomes, leading to increased mortality in the lobsters’ environment. Here, we tested the effects of OA-like conditions on the mechanical integrity of selected exoskeletal defenses of juvenile California spiny lobster, Panulirus interruptus. Young spiny lobsters reside in kelp forests with dynamic carbonate chemistry due to local metabolism and photosynthesis as well as seasonal upwelling, yielding daily and seasonal fluctuations in pH. Lobsters were exposed to a series of stable and diurnally fluctuating reduced pH conditions for three months (ambient pH/stable, 7.97; reduced pH/stable 7.67; reduced pH with low fluctuations, 7.67 ± 0.05; reduced pH with high fluctuations, 7.67 ± 0.10), after which we examined the intermolt composition (Ca and Mg content), ultrastructure (cuticle and layer thickness), and mechanical properties (hardness and stiffness) of selected exoskeletal predator defenses. Cuticle ultrastructure was consistently robust to pH conditions, while mineralization and mechanical properties were variable. Notably, the carapace was less mineralized under both reduced pH treatments with fluctuations, but with no effect on material properties, and the rostral horn had lower hardness in reduced/high fluctuating conditions without a corresponding difference in mineralization. Antennal flexural stiffness was lower in reduced, stable pH conditions compared to the reduced pH treatment with high fluctuations and not correlated with changes in cuticle structure or mineralization. These results demonstrate a complex relationship between mineralization and mechanical properties of the exoskeleton under changing ocean chemistry, and that fluctuating reduced pH conditions can induce responses not observed under the stable reduced pH conditions often used in OA research. Furthermore, this study shows that some juvenile California spiny lobster exoskeletal defenses are responsive to changes in ocean carbonate chemistry, even during the intermolt period, in ways that can potentially increase susceptibility to predation among this critical life stage.

Climate change combined with anthropogenic stressors (e.g. overfishing, habitat destruction) may have particularly strong effects on threatened populations of coastal invertebrates. The collapse of the population of European lobster (Homarus gammarus) around Helgoland constitutes a good example and prompted a large-scale restocking program. The question arises if recruitment of remaining natural individuals and program-released specimens could be stunted by ongoing climate change. We examined the joint effect of ocean warming and acidification on survival, development, morphology, energy metabolism and enzymatic antioxidant activity of the larval stages of the European lobster. Larvae from four independent hatches were reared from stage I to III under a gradient of 10 seawater temperatures (13–24°C) combined with moderate (∼470 µatm) and elevated (∼1160 µatm) seawater pCO2 treatments. Those treatments correspond to the shared socio-economic pathways (SSP), SSP1-2.6 and SSP5-8.5 (i.e. the low and the very high greenhouse gas emissions respectively) projected for 2100 by the Intergovernmental Panel on Climate Change. Larvae under the elevated pCO2 treatment had not only lower survival rates, but also significantly smaller rostrum length. However, temperature was the main driver of energy demands with increased oxygen consumption rates and elemental C:N ratio towards warmer temperatures, with a reducing effect on development time. Using this large temperature gradient, we provide a more precise insight on the aerobic thermal window trade-offs of lobster larvae and whether exposure to the worst hypercapnia scenario may narrow it. This may have repercussions on the recruitment of the remaining natural and program-released specimens and thus, in the enhancement success of future lobster stocks.

Increased demands of the seafood market have led to the rapid growth in crustacean aquaculture production in various parts of the world. Therefore, an expansion in the knowledge of the reproductive biology of crustaceans has become more important. Hormones released from the androgenic gland (AG) in crustaceans are liable for both the separation of primary and secondary sexual features and reproductive behavior. AG removal in male crustaceans causes a transformation of the intersex animals towards the females and a degeneration of spermatids and reproductive organs. AG implantation and injection of AG extracts are common approaches for crustacean masculinization. In this review, the importance of AG and its implication in crustacean aquaculture are reiterated, while the discovery, identification, chemical nature, and isolation of insulin-like androgenic gland hormone are also overviewed. [ABSTRACT FROM AUTHOR]

Behavioral variation in animals is often influenced by experience. Previous studies have found that daily threatening experiences can enhance fear- and anxiety-like behaviors in some vertebrates. However, it is unclear whether the change in fear/anxiety behavior occurs in invertebrates. The present study investigated whether fear/anxiety behavior could be affected by a net-chasing treatment in two shrimp species (Neocaridina denticulata ssp. and Palaemon pacificus). The net-chasing treatment was repeated for 8 days to simulate daily predator experiences, and behavioral tests (open-field, shelter-seeking, and escape-response tests) were conducted on the day following the last day of treatment. Net-chased N. denticulata ssp. displayed a tendency to remain near a wall compared with the control in the open-field test, whereas net-chased P. pacificus shrimps demonstrated greater escape behavior compared with the control in the escape-response test. These results suggest that fear/anxiety behavior for both shrimp species can be affected by the net-chasing treatment, although the pattern of behavioral change differed between the two species. The findings suggest that daily threatening experiences change the behavior of shrimp and cause them to select a regular avoidance strategy when they encounter risks and unknown situations. [ABSTRACT FROM AUTHOR]

In vertebrate reproduction, metabolism, growth and development, essential roles are played by glycoprotein hormones, such as follicle-stimulating hormone (FSH), luteinizing hormone (LH) and thyroid-stimulating hormone (TSH), all of which are heterodimers consisting of two subunits, a structurally identical alpha subunit, and a variable beta subunit, which provides specificity. A 'new' glycoprotein hormone heterodimer identified in both vertebrates and invertebrates, including decapod crustaceans, was shown to be composed of the glycoprotein alpha 2 (GPA2) and glycoprotein beta 5 (GPB5) subunits. The putative receptor for GPA2/GPB5 in invertebrates is the leucine-rich repeat-containing G protein-coupled receptor 1 (LGR1). In this study in the giant freshwater prawn, Macrobrachium rosenbergii , we identified and characterized the GPA2 (MrGPA2) , GPB5 (MrGPB5) and LGR1 (MrLGR1) encoding genes and revealed their spatial expression patterns in female animals. Loss-of-function RNA interference (RNAi) experiments in M. rosenbergii females demonstrated a negative correlation between MrGPA2/MrGPB5 silencing and MrLGR1 transcript levels, suggesting a possible ligand–receptor interaction. The relative transcript levels of M. rosenbergii vitellogenin (MrVg) in the hepatopancreas were significantly reduced following MrGPA2/MrGPB5 knockdown. MrLGR1 loss-of-function induced MrVg receptor (MrVgR) transcript levels in the ovary and resulted in significantly larger oocytes in the silenced group compared to the control group. Our results provide insight into the possible role of GPA2/GPB5-LGR1 in female reproduction, as shown by its effect on MrVg and MrVgR expression and on the oocyte development. Here, we suggest that the GPA2/GPB5 heterodimer act as a gonad inhibiting factor in the eyestalk-hepatopancreas-ovary endocrine axis in M. rosenbergii. [ABSTRACT FROM AUTHOR]

Post-autotomy appendage movement has evolved independently in several vertebrate and invertebrate taxa. Moving appendage may divert a predator's attention away from the body, allowing the prey to escape. Decapod crustaceans, particularly anomuran and brachyuran crabs, have been well studied in terms of autotomy; however, no studies have focused on post-autotomy limb behaviour. We first found post-autotomy limb movement in decapod crustaceans using the porcellanid crab Petrolisthes japonicus. Porcellanid crabs possess large chelipeds. The porcellanid crab autotomizes the cheliped readily when a predator crab grasps it by the cheliped, enabling it to escape. Our laboratory observations revealed that autotomized chelipeds of P. japonicus moved voluntarily: they repeated closing and stretching movements of the chela and remaining parts on the propodus-carpus joint. The number of strokes (a single sequential closing and stretching movement) and the total stroke duration of the chelipeds were about 28 times and 17 sec on average, respectively. Post-autotomy cheliped movement may further improve the anti-predator defence efficacy of large chelipeds with a hair-trigger autotomy response in porcellanid crabs. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) are widely distributed effector molecules that provide a first line of defence for organisms that lack adaptive immunity, such as crustaceans. They also represent bioactive molecules with great potential as therapeutic agents in aquaculture and biomedicine. Over the last years, an intensive research effort has been devoted to the identification and characterisation of antimicrobials in crustaceans resulting in the recognition of twelve gene‐encoded AMP families to date. In addition to classical linear and multi‐domain AMPs, crustaceans also rely on the production of unconventional ones, such as lysozymes and AMPs encrypted in large proteins carrying nonimmune functions. Besides their molecular and functional diversity, crustaceans have a particular AMP repertoire usually composed of diverse multigene families of taxonomically restricted peptides/polypeptides. In fact, only a few families of AMPs are shared between crustaceans and their close arthropod relatives. This review celebrates the silver jubilee of the discovery of the first crustacean AMPs and presents an updated and comprehensive overview in terms of structure, diversity and biological properties, emphasising their role in immune responses and in host‐microbe interactions. We also discuss the main progress achieved so far and major challenges remaining. [ABSTRACT FROM AUTHOR]

In vertebrate reproduction, metabolism, growth and development, essential roles are played by glycoprotein hormones, such as follicle-stimulating hormone (FSH), luteinizing hormone (LH) and thyroid-stimulating hormone (TSH), all of which are heterodimers consisting of two subunits, a structurally identical alpha subunit, and a variable beta subunit, which provides specificity. A 'new' glycoprotein hormone heterodimer identified in both vertebrates and invertebrates, including decapod crustaceans, was shown to be composed of the glycoprotein alpha 2 (GPA2) and glycoprotein beta 5 (GPB5) subunits. The putative receptor for GPA2/GPB5 in invertebrates is the leucine-rich repeat-containing G protein-coupled receptor 1 (LGR1). In this study in the giant freshwater prawn, Macrobrachium rosenbergii, we identified and characterized the GPA2 (MrGPA2), GPB5 (MrGPB5) and LGR1 (MrLGR1) encoding genes and revealed their spatial expression patterns in female animals. Loss-of-function RNA interference (RNAi) experiments in M. rosenbergii females demonstrated a negative correlation between MrGPA2/MrGPB5 silencing and MrLGR1 transcript levels, suggesting a possible ligand–receptor interaction. The relative transcript levels of M. rosenbergii vitellogenin (MrVg) in the hepatopancreas were significantly reduced following MrGPA2/MrGPB5 knockdown. MrLGR1 loss-of-function induced MrVg receptor (MrVgR) transcript levels in the ovary and resulted in significantly larger oocytes in the silenced group compared to the control group. Our results provide insight into the possible role of GPA2/GPB5-LGR1 in female reproduction, as shown by its effect on MrVg and MrVgR expression and on the oocyte development. Here, we suggest that the GPA2/GPB5 heterodimer act as a gonad inhibiting factor in the eyestalk-hepatopancreas-ovary endocrine axis in M. rosenbergii.

Crustacean hyperglycemic hormone superfamily neuropeptides (CHHs) are typical crustacean eyestalk hormones that include the crustacean hyperglycemic hormone (CHH), moult-inhibiting hormone (MIH), vitellogenesis/gonad-inhibiting hormone (VIH/GIH) and mandibular organ-inhibiting hormone (MOIH), which are divided into two subfamilies: type I CHH (included CHH) and type II CHH (consisting of MIH, VIH/GIH, and MOIH). They are involved in various biological activities, such as metabolism, molting, reproduction, and osmotic regulation. Discovery of the ion transport peptide (ITP) in insects expanded the members of CHHs and revealed that CHHs are not restricted to crustaceans. In this study, we focused on three economically important crabs: the mud crab, Scylla paramamosain, the swimming crab, Portunus trituberculatus, and the Chinese mitten crab, Eriocheir sinensis. Their genomes, Pacbio full-length transcriptomic data as well as comparative RNA-seq data were obtained and used to analyze the genomic structures and expression patterns of CHHs and their putative receptors through bioinformatic methods. Two type I CHH members (CHH1 and CHH2) were identified, of which CHH1 had two splice variants, CHH1-v1 and CHH1-v2. One copy of type II CHH (MIH) was found in P. trituberculatus and E. sinensis. While most decapods, including S. paramamosain, have two copies of type II CHHs (MIH/VIH), these MIH/VIHs are adjacent to each other on the same chromosome. Besides type I and II CHH, ITP-like peptides have also been found in the three crabs, and they are mainly expressed in the eyestalk. Four, five, and three G protein-coupled receptors (GPCRs) were identified in S. paramamosain, P. trituberculatus, and E. sinensis, respectively, which might be putative CHH receptors. These GPCRs were divided into three groups. One group was composed of two contiguous genomic position GPCRs, and they were mainly expressed in the hepatopancreas. These findings provide a basis for further studies on CHHs receptor binding tests and on CHHs/GPCRs signaling pathways.

Assessing decapod sensitivity to regional-scale ocean acidification (OA) conditions is limited because of a fragmented understanding of the thresholds at which they exhibit biological response. To address this need, we undertook a three-step data synthesis: first, we compiled a dataset composed of 27,000 datapoints from 55 studies of decapod responses to OA. Second, we used statistical threshold analyses to identify OA thresholds using pH as a proxy for 13 response pathways from physiology to behavior, growth, development and survival. Third, we worked with the panel of experts to review these thresholds, considering the contributing datasets based on quality of the study, and assign a final thresholds and associated confidence scores based on quality and consistency of findings among studies. The duration-dependent thresholds were within a pH range from 7.40 to 7.80, ranging from behavioral and physiological responses to mortality, with many of the thresholds being assigned medium-to-high confidence. Organism sensitivity increased with the duration of exposure but was not linked to a specific life-stage. The thresholds that emerge from our analyses provide the foundation for consistent interpretation of OA monitoring data or numerical ocean model simulations to support climate change marine vulnerability assessments and evaluation of ocean management strategies.

The wide geographic distribution, large size and ease of capture has led to decapod crustaceans being used extensively in laboratory experiments. Recently in the United Kingdom decapod crustaceans were listed as sentient beings, resulting in their inclusion in animal care protocols. Ironically, little is known about how captive conditions affect the survival and general condition of wild decapod crustaceans. We used the green shore crab, Carcinus maenas, to investigate the effects of stocking density and shelter on survival and vitality indices during a 6 month period in the laboratory. Neither stocking density nor the presence of shelter affected survival. Stocking density also had no effect on the vitality indices (limb loss, claw strength, BRIX, righting time, leg flare and retraction). The presence of shelter did affect the number of limbs lost and the leg retraction response, but had no effect on the other vitality indices. All vitality indices changed, and mortality increased over time, independent of treatment: this became most apparent after 8 to 11 weeks storage in the laboratory. This decline in condition may have been due to repeated handling of the crabs, rather than the stocking conditions. In support of this, untracked, non-handled (control) individuals sustained a 4% mortality rate compared with 67% mortality in experimental crabs during the 6 month period. Although simple experimental monitoring of crabs with biweekly vitality tests only produced transient short-term stress events, the repeated handling over time apparently led to a cumulative stress and a deterioration in animal health. Bringing wild crustaceans into the laboratory and holding them, even with modest experimental manipulation, may result in high mortality rates. Researchers and animal care committees need to be aware that wild captive invertebrates will respond very differently to laboratory-bred vertebrates, and plan experiments accordingly.

Lipids are the main energy source for embryonic development in oviparous animals. Prior to the utilization and catabolism, lipids are primarily transported from the yolk sac to embryonic tissues. In the present study, cDNA encoding a circulatory large lipid transfer protein (LLTP) superfamily member, the precursor of large discoidal lipoprotein (dLp) and high-density lipoprotein/β-1,3-glucan-binding protein (HDL-BGBP), named dLp/HDL-BGBP of 14,787 bp in length, was cloned from the mud crab Scylla paramamosain. dLp/HDL-BGBP was predicted to encode a 4,831 amino acids (aa) protein that was the precursor of dLp and HDL-BGBP, which were both detected in hemolymph by liquid chromatography–mass spectrometry (LC-MS/MS) analysis. For the intracellular LLTP, three microsomal triglyceride transfer protein (MTP) cDNAs of 2,905, 2,897, and 3,088 bp in length were cloned from the mud crab and were predicted to encode MTP-A of 881 aa, MTP-B of 889 aa, and MTP-C of 919 aa, respectively, which were different merely in the N-terminal region and shared an identical sequence of 866 aa. During embryonic development, the expression level of dLp/HDL-BGBP consecutively increased from the early appendage formation stage to the eye pigment-formation stage, which indicated that HDL-BGBP is probably the scaffolding protein for yolk lipid. For the MTP gene, MTP-C accounted for ~70% of MTP mRNA from the blastocyst stage to the nauplius stage, as well as the pre-hatching stage; MTP-C and MTP-A expression levels were comparable from the early appendage formation stage to the late eye pigment-formation stage; MTP-A was extremely low in blastocyst and gastrula stages; MTP-B was expressed at a relatively low-level throughout embryo development. The variations in the expression profiles among MTP transcripts suggested that MTP might play roles in the lipid droplet maturation and lipoprotein assembly during embryonic development.

Lipids are the main energy source for embryonic development in oviparous animals. Prior to the utilization and catabolism, lipids are primarily transported from the yolk sac to embryonic tissues. In the present study, cDNA encoding a circulatory large lipid transfer protein (LLTP) superfamily member, the precursor of large discoidal lipoprotein (dLp) and high-density lipoprotein/β-1,3-glucan-binding protein (HDL-BGBP), named dLp/HDL-BGBP of 14,787 bp in length, was cloned from the mud crab Scylla paramamosain. dLp/HDL-BGBP was predicted to encode a 4,831 amino acids (aa) protein that was the precursor of dLp and HDL-BGBP, which were both detected in hemolymph by liquid chromatography–mass spectrometry (LC-MS/MS) analysis. For the intracellular LLTP, three microsomal triglyceride transfer protein (MTP) cDNAs of 2,905, 2,897, and 3,088 bp in length were cloned from the mud crab and were predicted to encode MTP-A of 881 aa, MTP-B of 889 aa, and MTP-C of 919 aa, respectively, which were different merely in the N-terminal region and shared an identical sequence of 866 aa. During embryonic development, the expression level of dLp/HDL-BGBP consecutively increased from the early appendage formation stage to the eye pigment-formation stage, which indicated that HDL-BGBP is probably the scaffolding protein for yolk lipid. For the MTP gene, MTP-C accounted for ~70% of MTP mRNA from the blastocyst stage to the nauplius stage, as well as the pre-hatching stage; MTP-C and MTP-A expression levels were comparable from the early appendage formation stage to the late eye pigment-formation stage; MTP-A was extremely low in blastocyst and gastrula stages; MTP-B was expressed at a relatively low-level throughout embryo development. The variations in the expression profiles among MTP transcripts suggested that MTP might play roles in the lipid droplet maturation and lipoprotein assembly during embryonic development. [ABSTRACT FROM AUTHOR]

Some species of shrimp, lobster and crabs known as decapod (ten feet) crustase are among the economically important aquatic organisms. The increase in peoples protein needs leads to the inadequate consumption of these organisms caught from the nature and the consumption of them as a luxury food in general. Therefore, there has been a significant increase in the reproduction and rearing of decapod crustaceans, especially in recent years. It is of great importance to know the reproductive systems and to investigate the factors affecting this system in the studies to increase the production of decapods. In this study, informations on the external and internal factors that are effective in the regulation of growth in crustaceans, and the role of hormones and neurotransmitters in the reproduction of crustaceans were reviewed. The most important external factors in growth regulations in crustaceansare water temperature, photoperiod, feeding, salinity on the other hand, among internal factors, neuroendocrine and non-neuroendocrine secretions appear to be effective on gonadal growth in crustaceans. [ABSTRACT FROM AUTHOR]

The redclaw crayfish, Cherax quadricarinatus (von Martens, 1868), a tropical freshwater crayfish endemic to Northern Australia and Southern Papua New Guinea, was introduced to the island of Puerto Rico in the late 1990's. Redclaw has established populations within man-made reservoirs and ponds across the island, where impoundments have impeded the migration and recruitment of native decapods, potentially opening niche space for the redclaw. We present a case study focused on documenting the presence/ absence, sex ratio, size class, and standing stock biomass of redclaw populations from six reservoirs (Carraízo, Cidra, Carite, Güajataca, El Guineo, Dos Bocas), as well as from various holding ponds of an aquaculture facility (Caribe Fisheries) located near the town of Lajas in the southwestern part of the island where the crayfish are considered pests. Crayfish were detected in 5 out of the 7 sample locations (Carraízo, Cidra, Carite, Güajataca, and Caribe Fisheries). A total of N = 150 crayfish were caught during sampling, with 91% being adults (N = 136) and sex counts resulting in a 0.81 male to female ratio. Standard Carapace Length (SCL) ranged from 16 mm (Güajataca) to 82 mm (Carraízo). No significant difference in SCL was found between adult males (48.32 mm ± 1.62 SE) and females (48.17 mm ± 1.47 SE) (F(1,134) = 0.81, P = 0.37), as well as between SCL in M:F ratio among sample sites (F(4,134) = 0.84, P = 0.50). However, a significant difference in total mean SCL among sample sites was found (F(4,134) = 16.96, P < 0.0001). A post-hoc Tukey-Kramer test indicated that individuals in Carraízo, located close to the area of initial redclaw introduction into the headwaters of the Loiza River, had the largest mean SCL (61.38 mm). Mean standing stock biomass per individual ranged from 1.46 g (Güajataca) to 9.71 g (Carraízo). These biomass estimates provide the first insight into the energy supplements that redclaw provides to higher trophic levels (e.g. predatory fish) in these reservoirs. Furthermore, with populations of native decapods having been completely extirpated from most impounded watersheds, introduced redclaw could fill in the empty niche space by processing organic matter and by providing a direct consumption item to recreational fish species. This could reestablish the missing links in the cycling of nutrients and transfer of energy within reservoirs. [ABSTRACT FROM AUTHOR]

Deciding which animals are sentient is an important precursor for decisions about the application of animal welfare legislation, and the wider assessment of the impacts of policies on animal suffering. We ascribe sentience in order to inform decisions about how animals should be treated, and how their treatment should be regulated. This ascription is both an ethical and an evidential process, and what evidence to use and require are ethical questions. Policymakers, therefore, cannot simply rely on scientific evidence in an ethically neutral way, but must be conscious of the ethical assumptions and positions underlying the process of ascription and its application in policy and law. As such, ethical principles that apply to policymaking apply to the ascription of sentience. This paper considers the implications of the Nolan principles for public service on the ascription of animals.

Consumer demand for invertebrates is on the rise as their numbers in the wild dwindle. However, with the growing conservation efforts of modern zoos and aquariums, and evidence from over 300 studies showing that invertebrates are capable of sentience, public interest, and moral concern for welfare of invertebrates have increased. The challenge for zoos and aquariums is in developing an objective and repeatable method for evaluating welfare that can be applied to invertebrates in zoological collections. Recently introduced into zoological collection management is the Animal Welfare Assessment Grid (AWAG). The AWAG helps to identify negative and positive welfare states, through assessing animal- and environmental-based indicators to make changes that lead to a better quality of life. Originally developed for the assessment of laboratory primates, the system has been successfully adapted to assess a variety of taxa across different environments, facilitated by the development of cloud-based software. In this study, the AWAG has been adapted to assess the cumulative lifetime experience of captive decapods and cephalopods at two different institutions, Marwell Zoo and National Marine Aquarium. This study has provided further evidence that the AWAG is adaptable and demonstrates the first time any objective scoring system has been successfully adapted for use in invertebrates. Through graphical representation, the results show that the AWAG identifies changes in welfare scores that can be attributed to specific events and can be used to predict the future vulnerability of species to welfare changes and suggest alternative management methods. This monitoring tool provides a versatile method of implementing practical welfare monitoring in zoos and aquariums.

I review studies that examined the possibility of pain experience in fish and note how they provided guidance on general methods that could be applied to other animals such as decapod crustaceans. The fish studies initially reported the occurrence of prolonged rocking movements in trout and rubbing of their lips if they were injected with acetic acid. Subsequent studies examined the role of morphine in reducing these activities and examined shifts in attention when responding to noxious stimuli. Various studies take up these themes in decapods. The results reported for the two taxonomic groups are remarkably similar and indicate that responses of both go beyond those expected of mere nociceptive reflex. Thus, the idea of pain cannot be dismissed by the argument that fish and decapods respond only by reflex. The responses of both clearly involve central processing, and pain experience, although not proven for either, is a distinct possibility. These studies have been the subjects of highly critical opinion pieces and these are examined and rebutted. The conclusion is that both fish and decapods should be awarded consideration for their welfare.

A compilation of halacarid mite species (Halacaridae) found associated with decapod crustaceans (Arthropoda, Crustacea, Decapoda) has been carried out based on published records. In this paper, we listed 24 species associated with crustaceans altogether. These 24 species belong to 10 genera, viz. Arhodeoporus (1 species), Astacopsiphagus (1 species), Copidognathus (11 species), Halacarellus (2 species), Limnohalacarus (1 species), Lohmannella (1 species), Porohalacarus (1 species), Porolohmannella (1 species), Soldanellonyx (2 species), Thalassarachna (3 species). Majority of the association types are probably commensals or occasional invaders in nature and only a few species are assumed to be parasitic. [ABSTRACT FROM AUTHOR]

Eusociality is a highly conspicuous and ecologically impactful behavioral syndrome that has evolved independently across multiple animal lineages. So far, comparative genomic analyses of advanced sociality have been mostly limited to insects. Here, we study the only clade of animals known to exhibit eusociality in the marine realm—lineages of socially diverse snapping shrimps in the genus Synalpheus. To investigate the molecular impact of sociality, we assembled the mitochondrial genomes of eight Synalpheus species that represent three independent origins of eusociality and analyzed patterns of molecular evolution in protein-coding genes. Synonymous substitution rates are lower and potential signals of relaxed purifying selection are higher in eusocial relative to noneusocial taxa. Our results suggest that mitochondrial genome evolution was shaped by eusociality-linked traits—extended generation times and reduced effective population sizes that are hallmarks of advanced animal societies. This is the first direct evidence of eusociality impacting genome evolution in marine taxa. Our results also strongly support the idea that eusociality can shape genome evolution through profound changes in life history and demography. [ABSTRACT FROM AUTHOR]