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In the previous companion paper, the possibility of learning by Chasmagnathus in field conditions was demonstrated. Here, we study long-term memory inquiring to what extent an internal representation could be maintained in a complex environment. Two 45-min training sessions, each of 15 visual danger stimulus presentations with 3-min intertrials, were given at a 24-h interval. Throughout the first training session and during the first 22.5 min of re-training on day 2, crabs kept the same hiding response level but then, during the second phase of re-training, the re-emerging increased up to the point that 32% of surface crabs ignored the stimulus. Each session was followed by a 22.5-min testing without stimulation. At testing on day 2 after re-training, crabs showed a change in the usual exploring strategy. Results reveal long persistency in responding despite a rest interval of 24 h followed by a gradual decrease in response until it vanishes. The statistical analysis was performed by comparing performances at day 2 (Rescorla in Am Psychol 43:151–160, ) and then confirmed through comparisons between day 1 and day 2. However, it is not possible to identify separate and taxonomically well-defined learnings but rather a tangled collection of processes that influence each other blurring some of the diagnostic features of each learning. [ABSTRACT FROM AUTHOR]

The paper presents the results from a study of the population structure of alien snow crabs Chionoecetes opilio in the western Kara Sea near the Kara Strait using two methods: Sigsby trawling and video surveillance. The towed unmanned underwater vehicle Videomodule was used to estimate the population density of crabs: 0.55 ind/m2 in 2016, and 0.17 and 0.09 ind/m2 in 2017. No differences were revealed when comparing the size structure of the crab population based on the two methods. An exception is possible underestimation of younglings with a carapace width <20 mm when using the Videomodule. The minimum observed carapace size was ~10 mm, and the maximum, 127 mm. Both methods revealed the presence of all stages of crab growth, which indicates successful survival and growth of this crab in the western Kara Sea. An adequate assessment of the development of invasion of alien C. opilio in the Kara Sea requires annual video observations in the regions representing characteristic biotopes at different distances from the Kara Strait. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

This paper provides an overview of pea crabs of the genus Pinnixa White, 1846 (Brachyura: Pinnotheridae) that occur along the Russian coast of the Sea of Japan. Three species of the genus have been recorded for this area: P. tumida Stimpson, 1858, P. rathbuni Sakai, 1934, as well as P. banzu Komai, Nishi & Taru, 2014, which is the first record for the fauna of Russia. All species clearly differ ecologically: P. tumida was found in Posyet Bay in the intestine of the burrowing holothurian Paracaudina chilensis (Müller, 1850); P. rathbuni, in burrows of the echiuroid Urechis unicinctus (von Drasche, 1881); and P. banzu, in tubes of the polychaete Chaetopterus cautus Marenzeller, 1879. The paper also provides a definitive key to Pinnixa species and data on the size, behavior, symbionts, and parasites of P. rathbuni and P. banzu. [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 present paper reports five species of squat lobster, genus Agononida Baba and de Saint Laurent, 1996, of which A. squamosa (Henderson, 1885) and A. cf. variabilis (Baba, 1988) were not previously reported in Chinese waters. All the specimens are kept in the Marine Biological Museum collection in the Institute of Oceanology, Chinese Academy of Sciences, Qingdao. To date, there have been 11 species of this genus recorded from China’s seas. A key to those species is provided in this paper. [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 paper analyzes published and original data on the current distribution of alien species of malacostracan crustaceans including representatives from the orders Amphipoda, Mysidacea, Isopoda, Cumacea, and Decapoda in the Gulf of Finland (eastern part of the Baltic Sea). Thus far, 12 alien species of allochthonous origin have been recorded in this area. Also, seven species of malacostracans are known as actively spreading species in neighboring regions and therefore as potential invaders to the Gulf of Finland. The invasion history of the alien species and possible vector of their expansion from the original areas to the study area are discussed. [ABSTRACT FROM AUTHOR]

Abstract  This review re-addresses the question: Where does metamorphosis to the puerulus mainly take place among the shallow-water palinurids? A decade ago we reviewed this ecological question in a paper that focused on phyllosomal development of the western rock lobster, Panulirus cygnus. The main region of occurrence of its metamorphosis was found to be in the slope region beyond the shelf break. Because the puerulus of P. cygnus is a non-feeding stage, it was hypothesised that metamorphosis will not occur until the final phyllosoma has reached some critical, and specific, level of stored energy reserves. For late larval development and successful metamorphosis of P. cygnus, the richest food resources seem to be located in the slope waters adjoining the shelf break off Western Australia. This, like most shelf break areas, is a region of higher zooplankton and micronekton biomass than is usually found further offshore, and is dominated (in winter-spring months) by the warm south-flowing Leeuwin Current. In this new review, distribution and abundance data of final phyllosomas and pueruli are examined from, Panulirus argus, Panulirus cygnus, Panulirus japonicus, Panulirus ornatus and Jasus edwardsii, and where possible, related to features of the satellite imagery of the areas in which they occur. We hypothesise that metamorphosis will occur where the final stages have partaken of sufficient, appropriate nutrition to provide them with a reserve of bioenergetic resources, and this can occur where oceanographic fronts effect greater planktonic productivity and concentrations of food organisms. This may be near the shelf-break, or out to large distances offshore, because of large-scale oceanographic events such as the prevailing current system, its off-shoots, mesoscale eddy fronts, counter-currents, etc. However, we contend that, in terms of population recruitment, metamorphosis in most shallow-water palinurid species occurs mainly in the slope waters adjoining the shelf break of the region to which the species is endemic. Although some final phyllosomas may metamorphose much further offshore, it is unlikely that these pueruli will reach the shore, let alone settle and successfully moult to the juvenile stage. All of the data indicate that successful metamorphosis from the final-stage phyllosoma to the puerulus stage in all species occurs offshore but close to the continental shelf. [ABSTRACT FROM AUTHOR]

To respond appropriately to communication signals, animals must have the ability to decipher signal meaning. At a basic level, interpreting the difference between territorial and courtship signals can be vital for the survival and reproduction of social animals. Male and female fiddler crabs communicate with claw-waving displays, but the function of these waves remains uncertain. Species differ in the context in which they wave: Some wave during courtship, some during territorial defence and some during both. In this paper, we provide evidence that males of an Australian species of fiddler crab, Uca perplexa, use two different types of claw waving display, lateral and vertical. Lateral waves are employed solely in a courtship context, whilst vertical waves are employed during courtship as well as territorial interactions. Using video recordings, we show that lateral waves were produced spontaneously (broadcast), and their frequency increased only in the presence of female wanderers. Vertical waves were not broadcast but were elicited by male wanderers during agonistic interactions and female wanderers during close range courtship. Male resident U. perplexa were able to discriminate the sex of wandering crabs on the mudflat at distances of 32 cm. During all resident–wanderer interactions, residents attempted to maintain a position directly between the wanderer and the home burrow and orient themselves to face females and to present the major claw towards males. To our knowledge, this is the first demonstration of the multiple use of waving displays in a fiddler crab species. [ABSTRACT FROM AUTHOR]

Due to their life cycle shared between rivers and oceans, amphidromous organisms serve as intriguing models for studying biogeography. To investigate the implications of their unique life history, we examined the population structure of the amphidromous shrimp Caridina natalensis across its known range in the South Western Indian Ocean. A total of 118 specimens were collected from 7 islands (Mayotte, Mohéli, Mahé, Praslin, Silhouette, Mauritius and Madagascar) and the African mainland (South Africa), and their 16S rRNA and Cox1 mitochondrial genes were sequenced. Our findings reveal significant regional structure among archipelagos, suggesting complex patterns of dispersal involving successive events of extinction-recolonization. By conducting a comparative analysis with six other amphidromous species from the South Western Indian Ocean, based on literature sources, we were able to draw conclusions regarding the amphidromous biogeography of the area. Furthermore, we propose a novel classification of amphidromous species, considering their population structure and life history traits. We defined four categories of increasing dispersal abilities and decreasing genetic population structure: 1. Land-locked species; 2. Species with reduced or facultative amphidromy; 3. Species with common amphidromy; and 4. Super-amphidromous species. Lastly, we identified the Comoros Islands (namely Mayotte and Mohéli) as a critical area for the dispersal of amphidromous species, emphasizing the need for prioritizing conservation efforts in this region. [ABSTRACT FROM AUTHOR]

Myxobdella sinanensis Oka, 1925 (Arhynchobdellida, Praobdellidae) is endemic to Japan, and was recently observed attaching to the freshwater Japanese crab, Geothelphusa dehaani White, 1847 (Decapoda, Potamidae), revealing that M. sinanensis is a facultative parasite of G. dehaani. Although they both inhabit headwater streams in Japan, their interactions and behavioral responses have not been investigated before. We hypothesized that G. dehaani reacts to M. sinanensis through (1) chemical cues, and (2) visual cues or physical contact in addition to the chemical cues. Two experiments were conducted in a container in which G. dehaani could hide under a rock on the bottom covered with sediment. The duration of activity outside the rock and distance moved before and after introducing rearing water of M. sinanensis, or live M. sinanensis, was measured. No statistical difference was observed in movement distance, behavior, and time outside the rock in G. dehaani, indicating limited sensitivity to chemical cues. G. dehaani remained beneath the rock for a statistically shorter period after M. sinanensis was introduced into the container, indicating its dependence on visual and/or physical cues. It showed altered behavior by remaining stationary and escaping, confirming importance of visual and contact stimuli to escape the ectoparasite. [ABSTRACT FROM AUTHOR]

Establishment of artificial reefs and no-take areas are management measures available for restoring deteriorated marine ecosystems, compensating for habitat loss and strengthening harvested populations. Following the establishment of no-take artificial reefs in western Sweden to compensate for hard bottoms lost to a shipping lane, we detected rapid positive effects on crustaceans and demersal fish compared to fished reference areas. The relative abundance and size structure of European lobster (Homarus gammarus) increased strongly in the no-take area indicating more than doubled and tripled egg production in 5 and 10 years, respectively. For benthic fish and crustacean communities, the abundances of gadoids and wrasses increased and the abundances of small decapod crustaceans decreased in the no-take area, likely indicating cascading effects of increased predation. The study demonstrates that relatively small no-take areas, enhanced by artificial reefs, can rapidly invigorate populations of lobster and fish that in turn may re-initiate local top-down control. [ABSTRACT FROM AUTHOR]

Xenophthalmus pinnotheroides is a tiny subtidal marine crab from the West Pacific and Northern Indian Oceans. Its native range is poorly documented, with few records from the wild. Although it is not exploited by humans, degradation of suitable habitats by anthropogenic activities can significantly threaten this species. Here we bring the first record of the species in Vietnamese waters and prediction of its native range based on climate matching analysis. The areas of its potential occurrence are highlighted and future confirmation through field survey is recommended. The present findings indicate the range extension of X. pinnotheroides in Asia. [ABSTRACT FROM AUTHOR]

Based on the materials obtained in the Kara Sea, the size structure and sexual maturity of the male population of the invasive snow crab opilio (Chionoecetes opilio) are analyzed. Observations in the southern bays of the Novaya Zemlya archipelago and the Novaya Zemlya depression showed that the bulk of male crabs reach maturity at a carapace width (CW) above 60 mm. All captured males with CW of more than 67 mm underwent terminal molt. Only two males caught in the Novaya Zemlya trough reached the established commercial size of carapace width (CW) of 100 mm. The most numerous size group of adult males in the bays had CW of 60 mm, and 80–90 mm in the Novaya Zemlya trough. The obtained data allow us to assert that harvesting crabs with CW of 80–90 mm will not result in the removal of immature individuals and will not reduce the reproductive potential of the Kara Sea population beyond predicted levels of sustainable fishing. [ABSTRACT FROM AUTHOR]

The impact of dam reservoirs on river ecosystems is one of the current major issues in hydrobiology. In addition to the impact on native biodiversity, impoundments may facilitate biological invasions. A successful invasion is presumably related to the individual life history and resource allocation strategy in expanding populations. We tested whether reservoirs affect the body condition of invasive Faxonius limosus in upland streams. We found positive allometry of growth in females but more frequent isometric growth in males, and the form factor a3.0 was significantly higher in males than in females within populations. Fulton's condition factor (K) was calculated for standard carapace lengths of 20 mm (juvenile) and 40 mm (adult). Both mean KCL 20 and KCL 40 were higher in males than in females. Positive allometry of growth in females resulted in a larger mean KCL 40 than KCL 20. The majority of the mean K obtained in reservoirs was similar or lower than the respective condition in streams. The condition of adult females was higher in streams in comparison to reservoirs. The obtained results are in contrast to the hypothesis that reservoirs positively affect individual body conditions and show that these man-made lakes do not provide more favourable habitat conditions for F. limosus than those in the natural aquatic environments of an upland landscape. An advantageous effect of the presence of reservoirs on invasion spread may be possible in more ecologically harsh landscapes, especially in colder climatic zones. Our study is the first to investigate the relationship of the body condition of F. limosus in two contrasting habitats. [ABSTRACT FROM AUTHOR]

Recent records of the occurrence of a little-known ribbon worm, Nipponnemertes ogumai (Yamaoka ), along the Pacific coast of Honshu, Japan, are summarized with a map of known distribution. Photographs of the worm in its living state are provided, with brief descriptions of external morphology and behavior. Sequences of the nuclear 18S rDNA (1,785 bp) and 28S rDNA (2,215 bp), as well as the mitochondrial 16S rDNA (452 bp) and cytochrome c oxidase subunit I (COI) gene (621 bp) were determined. Preliminary maximum-likelihood phylogenetic analyses were performed together with some other congeners, viz., N. bimaculata (Coe ), N. pulchra (Johnston ), N. punctatula (Coe ), and two unidentified forms, for which sequences were available in the public databases. In the resulting tree, N. ogumai was nested within the congeners, consolidating the previous alteration of the generic placement of the species from Amphiporus Ehrenberg (-), to Nipponnemertes Friedrich . A contaminated cytochrome c oxidase subunit I (COI) sequence implied that N. ogumai may feed on caridean shrimps. [ABSTRACT FROM AUTHOR]

The sperm nucleus of the decapod crustacean Chinese mitten crab, Eriocheir sinensis, is loose and fibrous, which is a non-condensed nucleus. Our purpose was to analyze the structural distribution of the fusome-related protein Add1 during the spermatogenesis in E. sinensis to better understand the non-condensed nucleus of E. sinensis. RT-qPCR and western blot results showed that Add1 was expressed at the transcriptional and translational level during spermatogenesis of E. sinensis. Immunofluorescence results showed that Add1 was widely distributed in the process of spermatogenesis, including spermatogonia, spermatocytes, spermatids, and sperm. In the initial stage of sperm nucleus decondensation of E. sinensis, Add1 was widely expressed in the cytoplasm of spermatogonia. In the process from stage III spermatids to sperm, Add1 is mainly expressed in the nucleus. With the continuous differentiation of cells, Add1 gradually transferred from the cytoplasm to the nucleus. Our results indicated that the fusome-related protein Add1 might be involved in the spermiogenesis through the construction of a new nuclear skeleton to participate in the decondensation of sperm nuclei and the maintenance and protection of non-condensed chromatin. [ABSTRACT FROM AUTHOR]

The class Branchiopoda, whose origin dates back to Cambrian, includes ~ 1200 species which mainly occupy freshwater habitats. The phylogeny and systematics of the class have been debated for long time, until recent phylogenomic analyses allowed to better clarify the relationships among major clades. Based on these data, the clade Anostraca (fairy and brine shrimps) is sister to all other branchiopods, and the Notostraca (tadpole shrimps) results as sister group to Diplostraca, which includes Laevicaudata + Spinicaudata (clam shrimps) and Cladoceromorpha (water fleas + Cyclestherida). In the present analysis, thanks to an increased taxon sampling, a complex picture emerges. Most of the analyzed mitogenomes show the Pancrustacea gene order while in several other taxa they are found rearranged. These rearrangements, though, occur unevenly among taxa, most of them being found in Cladocera, and their taxonomic distribution does not agree with the phylogeny. Our data also seems to suggest the possibility of potentially homoplastic, alternative gene order within Daphniidae. [ABSTRACT FROM AUTHOR]

Aquatic organisms detect chemical cues to sense the local environment, for example, to find a mate, locate food, and identify danger. Knowledge of chemical cues can be used in aquaculture, in practical applications such as controlling mating behavior to increase fertility, enhance feeding, and decrease stress; in fisheries, by catching selected species with low-cost artificial attractants; and to address maritime issues, by decreasing biofouling. Aquatic organisms also detect chemical cues related to global environmental changes, ocean acidification, and increases in ocean plastics, all of which can affect their chemosensory behaviors. Here we discuss the nature of chemical cues and chemosensory biology and ecology of aquatic organisms, and potential applications with an emphasis on sex pheromones in commercially important and well-studied animals, namely, decapod crustaceans and fish. [ABSTRACT FROM AUTHOR]

The ranges of species are shifting as a consequence of anthropogenic climate change. In the marine realm biogeographic transition zones could form barriers to dispersal and inhibit range-shift, but little is known about this potential effect. The hermit crab Clibanarius erythropus appeared in the UK in 2016 with the nearest reproducing population being on the northern coast of Brittany. This raises questions of which conditions may have permitted C. erythropus to cross the English Channel (7.25°W, 49.00°N) and whether this barrier could be overcome by other intertidal species. Dispersal simulations suggest the larvae of C. erythropus arrived in 2014, originated from North Brittany, experienced a mean temperature of around 16 °C, and took longer than 20 days to be transported across the channel. The transportation of larvae from Brittany to the southwest UK appears to be rare and driven by occasional, unusual ocean currents. The English Channel may continue to prevent species with pelagic larvae that settle within 20 days, such as many species of gastropod, annelids, and macroalgae, from successfully range expanding to the UK. North Brittany was the only landmass from which it is feasible the UK population of C. erythropus could have originated. Therefore, species with long-lived pelagic larvae but without reproducing populations in North Brittany may not appear in the southwest UK until the species are established in North Brittany. The English Channel could continue to limit the ability of many intertidal species to shift their range with climate change. [ABSTRACT FROM AUTHOR]

Rhodolith distribution, morphology, and cryptofauna have been minimally studied on fringing reefs. We present the first study to examine both rhodolith distribution and associated cryptofauna in a tropical fringing reef, located along the microtidal, wave-dominated north shore of Moorea, French Polynesia. We find higher abundances of larger, rounder, and more branching rhodoliths in locations where longer waves impact the fringing reef. Among 1879 animals extracted and identified from 145 rhodoliths, ophiuroids, polychaetes, decapod crustaceans, and gastropods are most abundant, with a wide range of additional taxa contributing to diversity. Large and branching rhodoliths contain the greatest number and diversity of cryptofaunal organisms and are the preferred habitat of rigid-bodied, non-burrowing forms. Overall, exposure to waves entering the lagoon through passes appears to be a critical determinant of rhodolith abundance, morphotype, and in turn cryptofaunal composition in fringing reef habitats. [ABSTRACT FROM AUTHOR]

As the materials for this project, we used data on the distribution of the larvae of the Asian paddle crab Charybdis japonicus (A. Milne-Edwards, 1861); the spider crabs Hyas coarctatus ursinus (= Hyas ursinus) (Rathbun, 1924), Pugettia quadridens (de Haan, 1839), and Pisoides bidentatus (H. Milne-Edwards, 1873); the samurai crab Paradorippe granulata (= Dorippe granulata) (de Haan, 1841); the pea crab Pinnixa rathbuni (Sakai, 1934); and the porcelain crab Pachycheles stevensii (Stimpson, 1858) in Minonosok Bay of Pos'eta Bay obtained during 2000-2002 and in 2004. The planktonic samples were collected from the last third of May to September. The greatest density of the larvae was observed in May, mid-June, late June-early July, and late July-early August. The greatest densities of the crab larvae and the decapod larvae ranged from 20.4 to 48.2 and from 88.4 to 245.3 specimens/m. The schedule of the crab larvae's occurrence in the plankton is provided for the first time. The distribution of the density showed pronounced patchiness. [ABSTRACT FROM AUTHOR]

This study is concerned with determining the infection rates of the hermit crab of the family Diogenidae, living off the southern coast of the Crimean Peninsula, Black Sea, with representatives of the superorder Rhizocephala. Individuals of the hermit crab, Diogenes pugilator were identified as being invaded by the specific parasite, Septosaccus cuenoti, with the invasion extensity (prevalence) and intensity at 10.6% and 0–2 individuals, respectively. It examines the morphology of the external part of the female parasite, and the externa, as well as eggs developing inside it. The embryonic development of the egg was found to occur in four stages. Calculations performed for each growth stage include the major and minor diameters of the egg; the shape index, and area and volume; the number of eggs with the developing embryos in the externa; the potential number of nauplii hatched by the female Septosaccus cuenoti per generation; and the estimated share of their yield from the initial number of fertilized oocytes. [ABSTRACT FROM AUTHOR]

Purpose: Cymothoid isopods of the genus Nerocila are generally poorly known. The aim of this work was to document the first record of cymothoid isopod Nerocila exocoeti for the South-West Indian Ocean, representing a significant westward range extension for this species. Methods: A single adult, female N. exocoeti and 38 mancae specimens were collected from a live sharksucker Echeneis naucrates at D'Arros Island, Seychelles. The female isopod specimen was examined using a stereo microscope and described based on distinct morphological traits. Observations of novel behaviour were also made for E. naucrates. Results: The examined female isopod specimen measured 26 mm long by 10 mm wide. It possessed short coxae with the postero-lateral angles of pereonites 1–5 not produced and those of 6 and 7 reduced. The first antenna was composed of eight articles and the endopod of the uropod was half the length of the exopod. These traits confirm the specimen as N. exocoeti. Observations of novel behaviour in the wild host specimen showed the individual to deliberately and repeatedly swim ashore before thrashing in the substrate, returning to the water only once the isopod was removed. Conclusion: To date, N. exocoeti is known from India, Indonesia, Papua New Guinea and Taiwan. The present study represents the first record of N. exocoeti from the South-West Indian Ocean region and the first record of E. naucrates as a host of any cymothoid isopod. Additionally, N. exocoeti has previously only been recorded as parasitising beloniform fish hosts and these data present the first evidence of a perciform host for this species. The novel behaviour observed in E. naucrates likely represents a means to remove external parasites. [ABSTRACT FROM AUTHOR]

During the evolution of shrimp, essential aspects of their organization have remained unchanged. Approximately the same adaptations that have generated a large number of parallelisms within this relatively small group of arthropods have been used in the process of their adaptive evolution. This evolutionary process is typical telogenesis. The ancient shrimp fauna of both Dendrobranchiata and Pleocyemata may have originated in shallow waters not later than in the Jurassic. This is confirmed by the remains of Dendrobranchiata found in the shallow-water sediments of the Cenomanian (early Upper Cretaceous) and the remains of Pleocyemata as inhabitants of shallow-water refugia and representatives of the most primitive caridean shrimp family Procarididae. The last group is morphologically very similar to fossil shrimp of the Jurassic (for example, Udorella agassizi). Later, due to adaptive radiation at the generic level, shrimp occupied both the continental slope and the pelagic zone. These shallow-water species may have then been ousted by a new shrimp fauna during colonization of the shelf. The previous shrimp fauna may have been displaced to the continental slope, perhaps bordering on it. Some part of the species from various genera could have moved deeper along the slope down to the abyssal zone, whereas some others might have shifted to occupy the pelagic zone. This movement may have been associated with food resources, which were limited on the slope in the places with low levels of terrigenous sedimentogenesis. Numerous species seem to have switched from the detrital food chain to a grazing one. This process was repeated several times; as a result, the surviving representatives of the most ancient and subsequent fauna occurred at even greater depths. It follows from the above information that a pulsing type of telogenesis is characteristic of shrimp. Therefore, the modern shrimp fauna consists of young shelf groups with intensive cladogenesis, groups that have persisted since the Cretaceous (or even Jurassic), and remains of earlier fauna that have survived at great depths or in shallow-water refugia. [ABSTRACT FROM AUTHOR]

Based on original data, the most complete and updated species list of the water fleas (Crustacea: Cladocera) of both the southern part of the Russian Far East and Korea is represented. In total, 122 taxa are identified to the species level. The list includes 92 valid species recorded in the Far East of Russia and 71 in South Korea. Each taxon is attributed to one of the six zoogeographical groups: one among four faunistic complexes (widespread Eurasian, East Asian–American, endemic East Asian, and southern tropical), a group of widely distributed unrevised taxa, and a group of invasive species. With a decrease in latitude (i.e., in the north–south direction), (1) the species richness is decreased, (2) the dominance structure (based on species occurrence frequencies) is changed from two–three dominant species to a lack of clear dominants; (3) the rate of representatives of the widespread Eurasian complex is decreased, while that of the southern tropical taxa is increased, and (4) the taxocoenoses of the boreal type are changed to those of subtropical type. In addition to boreal and subtropical type taxocoenoses, three more taxocoenosis types are found in the Khanka Lake basin (the largest water body in the region). The relative abundance and occurrence of taxa from the endemic East Asian complex are similar within the entire region and do not vary with latitude. [ABSTRACT FROM AUTHOR]

Comparison between the number of taxa observed and the number expected in the absence of human impact is an easily understood and ecologically meaningful measure of biological integrity. This approach has been successfully applied to the assessment of the biological quality of flowing water sites using macroinvertebrates with the river invertebrate and classification system (RIVPACS) and its derivatives. In this paper, we develop a method similar to the RIVPACS predictive model approach to assess biological integrity at flowing-water sites using freshwater fish and decapod assemblages. We extend the RIVPACS approach by avoiding the biotic classification step and model each of the individual species separately. These assemblages were sampled at 118 least impacted (reference) sites in the Auckland region, New Zealand. Individual discriminant models based on the presence or absence of the 12 most common fish and decapod species were developed. Using the models, predictions were made using environmental measures at new sites to yield the probability of the capture of each of the 12 species, and these were combined to predict the assemblage expected at sites. The expected assemblage was compared to that observed using an observed over expected ratio (O/E). The models were evaluated using a number of internal tests including jackknifing, data partitioning, and the degree to which O/E values differed between reference sites and a set of sites perceived to be impaired by human impacts. [ABSTRACT FROM AUTHOR]

This paper reviews behavioral, physiological, anatomical, and ecological aspects of sound and vibration detection by decapod crustaceans. Our intent is to demonstrate that despite very limited work in this area in the past 20 years, evidence suggests that at least some decapod crustaceans are able to detect and use sounds in ways that parallel detection and processing mechanisms in aquatic and terrestrial vertebrates. Some aquatic decapod crustaceans produce sounds, and many are able to detect substrate vibration at sensitivities sufficient to tell of the proximity of mates, competitors, or predators. Some semi-terrestrial crabs produce and use sounds for communication. These species detect acoustic stimuli as either air- or substrate-borne energies, socially interact in acoustic "choruses," and probably use "calls" to attract mates. [ABSTRACT FROM AUTHOR]

Megalopas of 15 brachyuran crab species collected in the open sea plankton, and unknown until now, were identified using DNA barcodes (COI and 16S rRNA). Specimens belonging to the families Portunidae, Pseudorhombilidae and Xanthidae (Crustacea, Decapoda, Brachyura), and corresponding to the species Achelous floridanus, Arenaeus mexicanus, Callinectes amnicola, C. arcuatus, C. ornatus, C. toxones, Charybdis (Charybdis) hellerii, Portunus hastatus, Thalamita admete, Scopolius nuttingi, Etisus odhneri, Liomera cinctimanus, Neoliomera cerasinus, Pseudoliomera variolosa, and Williamstimpsonia stimpsoni, are described and illustrated, and compared with other congeneric species previously described. We also provide a new geographical record for N. cerasinus and the most remarkable features for each species. [ABSTRACT FROM AUTHOR]

In South America, apicomplexan parasites of the genus Hepatozoon have been sporadically detected in mammals. Previous studies in wild canids from Brazil and Argentina demonstrated infections by species genetically related to Hepatozoon americanum. The aim of the present work was to detect the presence of Hepatozoon in road-killed foxes encountered in Uruguayan highways. Blood samples from 45 crab-eating (Cerdocyon thous) and 32 grey pampean (Lycalopex gymnocercus) foxes were analyzed by PCR for Hepatozoon 18S rRNA gene. Eight foxes (10.4%) were found to be infected with an H. americanum-like protozoan, an Hepatozoon closely related to H. americanum. Bayesian and maximum-likelihood phylogenetic analyses revealed that the sequences obtained in this study cluster with H. americanum from the United States, and with an H. americanum-like species from dog and foxes from Brazil and Argentina. In the Unites States, H. americanum causes severe disease in dogs. In addition to this, an increasing habitat overlap between dogs and foxes makes the presence of H. americanum-like protozoan in foxes acquires veterinary relevance. This work represents the first report of L. gymnocercus infected with an H. americanum-like protozoan, and of wild canids infected with Hepatozoon in Uruguay. [ABSTRACT FROM AUTHOR]

Crustaceans were among the most valuable fishery resources in Hong Kong. However, the unrestricted and intensive use of different fishing gears, especially bottom trawling, has led to the depletion of commercially important crustaceans in Hong Kong since the 1980s. This study investigated whether commercial crustaceans recovered after the implementation of a permanent Hong Kong-wide trawl ban that began on December 31, 2012. Standardized field surveys were conducted using a commercial shrimp trawler at two sites in eastern and western waters of Hong Kong before (2004) and after the trawl ban (2013–2014 and 2015–2016) and two sites in southern waters after the trawl ban. Diversity, mean size, abundance, biomass and level of disturbance of commercial crustaceans from the three periods were investigated. The eastern waters exhibited an increased diversity of crustacean assemblages in Inner Tolo, and a higher abundance and biomass of crabs were detected in Outer Tolo after the trawl ban. Reduced disturbance, higher diversity in crustacean assemblages and greater abundance and biomass of predatory crabs were observed after the trawl ban in the outer estuary of western waters, and increased abundance and biomass of shrimp were detected in the inner estuary of western waters. No temporal or negative changes were detected in the southeast and southern waters of Lamma Island. The various responses of crustacean assemblages in Hong Kong waters revealed the critical role of complex interactions among multiple stresses, such as ongoing reclamation works, illegal trawling activities and increased fishing efforts using other (legal) fishing methods. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome (mitogenome) of animals can provide useful information for evolutionary and phylogenetic analyses. The mitogenome of the genus Exhippolysmata (i.e., Exhippolysmata ensirostris) was sequenced and annotated for the first time, its phylogenetic relationship with selected members from the infraorder Caridea was investigated. The 16,350 bp mitogenome contains the entire set of 37 common genes. The mitogenome composition was highly A + T biased at 64.43% with positive AT skew (0.009) and negative GC skew (− 0.199). All tRNA genes in the E. ensirostris mitogenome had a typical cloverleaf secondary structure, except for trnS1 (AGN), which appeared to lack the dihydrouridine arm. The gene order in the E. ensirostris mitogenome was rearranged compared with those of ancestral decapod taxa, the gene order of trnL2-cox2 changed to cox2-trnL2. The tandem duplication-random loss model is the most likely mechanism for the observed gene rearrangement of E. ensirostris. The ML and BI phylogenetic analyses place all Caridea species into one group with strong bootstrap support. The family Lysmatidae is most closely related to Alpheidae and Palaemonidae. These results will help to better understand the gene rearrangements and evolutionary position of E. ensirostris and lay a foundation for further phylogenetic studies of Caridea. [ABSTRACT FROM AUTHOR]

Nectonema, the only horsehair worm (Nematomorpha) genus found in marine environments, was previously known to be parasitic only in decapod crustaceans. We report Nectonema sp. as the first record of a marine nematomorph parasitic in isopod crustaceans. This is also the third record of marine nematomorphs from the North Pacific. Six infected isopods (Natatolana japonensis) collected from 1425 m of depth in the Sea of Japan each contained one to seven (mean 2.33) nematomorphs in the body cavity in the pereon. There was no correlation between the host body length and number of parasites. For Nectonema sp., we describe and illustrate morphological features of the parasitic juvenile stage and present nucleotide sequences for the cytochrome c oxidase subunit I gene (COI or cox1; 451 nt), 18S rRNA gene (1777 nt), and region spanning the internal transcribed spacer 1 (ITS1) and the 28S rRNA gene including the 5.8S rRNA gene and ITS2 (1218 nt in total). In an 18S maximum-likelihood tree that included 24 nematomorph species, Nectonema sp. grouped with N. agile from the northwestern Atlantic; the 18S gene from these two taxa was divergent by 11.8% K2P distance, suggesting that they are different species. Nectonema species may have a broader range of host groups than previously suspected, but may have been previously misidentified as nematode parasites. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess whether regulated river reaches show higher numbers of the spiny cheek crayfish Faxonius limosus, a common freshwater invader in Europe. Man-made alterations of riverine habitats may increase their susceptibility to biological invasions. This phenomenon is commonly studied in the context of dam reservoirs; however, the impact of river channelization and the resulting riverine habitat homogenization on the success of invasive species are mostly lacking. Surveys were conducted in natural and channelised river stretches in five rivers of south-central Poland. General linear mixed model analysis showed that crayfish abundance is usually higher at sites located within regulated reaches. The likely reason for the detected differences in abundance of crayfish may be related to decreased food-web complexity and lack of predators in a homogenised habitat. The results suggest that the channelization of small watercourses may increase the abundance of invasive species F. limosus and its pressure on native European crayfish. However, due to limited data obtained in field, our study should be considered as a pilot one. [ABSTRACT FROM AUTHOR]

In Yellowknife (Northwest Territories, Canada), roaster stack emissions from historic gold mining activities, particularly Giant Mine (1948–2004), have left a legacy of arsenic contamination in lakes. We examined Cladocera (Branchiopoda, Crustacea) subfossil remains in the recent and pre-industrial sediments of 23 lakes (arsenic gradient of 1.5–750 µg/l) within a 40 km radius of Giant Mine to provide a snapshot of regional change in Cladocera since pre-1850. We found that littoral and benthic taxa dominated the recent assemblages in high-[As] lakes (surface water [As] > 100 µg/l), while pelagic Bosmina was dominant in lakes with lower [As]. Cladocera richness and diversity were positively correlated with [As] (P = 0.004, R2 = 0.39; and P = 0.002, R2 = 0.46, respectively), except for four lakes with [As] > 100 µg/l. The lakes that showed the most pronounced changes in Cladocera since pre-1850 were those affected by both metal(loid) pollution and urban development, where complete shifts in the dominant taxa occurred. Lakes that were most heavily impacted by arsenic emissions did not experience notable shifts in Cladocera assemblages. Our study suggests that changes in Cladocera assemblages in mining-impacted subarctic lakes are modulated by local, lake-specific limnological conditions and the interaction of multiple stressors. [ABSTRACT FROM AUTHOR]

Expanding human activities alongside climate change, the introduction of invasive species and water contamination pose multiple threats to the unique marine ecosystems of the Pechora Sea in the Russian Arctic. Baseline data on biodiversity and responses to environmental change are urgently needed. Benthic decapod crustaceans are globally distributed and play an important role in fisheries, yet their roles in food webs are less understood. In this study, we used an integrated approach combining stomach content analysis and stable isotope analyses (δ13C and δ15N) to examine the trophic niches of three decapod species in the Pechora Sea including the invasive snow crab Chionoecetes opilio and two species of native decapods, the spider crab Hyas araneus and the hermit crab Pagurus pubescens. Stomach contents of 75 decapods were analysed (C. opilion = 23; H. araneusn = 9; P. pubescensn = 43), and 20 categories of prey items were identified with the most frequently occurring prey items being bivalve molluscs (Ciliatocardium ciliatum, Ennucula tenuis, Macoma calcarea), polychaetes, crustaceans and plant debris. Bayesian ellipse analyses of stable isotope signatures (n = 40) revealed that C. opilio displays an overlapping trophic niche with the two native decapods, providing direct evidence that the invader likely competes for food resources with both H. araneus and P. pubescens. As such, the presence of this invasive species could hold important consequences for trophic interactions, benthic ecosystem functioning and biodiversity. Microplastics were also found to be a likely stressor on this ecosystem, as 28% of all stomachs contained digested microplastics among other items. Long-term studies of benthic ecosystem structure and functioning are now needed to more fully understand the extent to which this new competitor may alter the future biodiversity of the Pechora Sea alongside the additional stressor of digested plastics. [ABSTRACT FROM AUTHOR]

The Wnt/β-catenin pathway participates in many important physiological events such as cell proliferation and differentiation in the male reproductive system. We found that Kinesin-2 motor KIF3A is highly expressed during spermatogenesis in Eriocheir sinensis; it may potentially promote the intracellular transport of cargoes in this process. However, only a few studies have focused on the relationship between KIF3A and the Wnt/β-catenin pathway in the male reproductive system of decapod crustaceans. In this study, we cloned and characterized the CDS of β-catenin in E. sinensis for the first time. Fluorescence in situ hybridization and immunofluorescence results showed the colocalization of Es-KIF3A and Es-β-catenin at the mRNA and the protein level respectively. To further explore the regulatory function of Es-KIF3A to the Wnt/β-catenin pathway, the es-kif3a was knocked down by double-stranded RNA (dsRNA) in vivo and in primary cultured cells in testes of E. sinensis. Results showed that the expression of es-β-catenin and es-dvl were decreased in the es-kif3a knockdown group. The protein expression level of Es-β-catenin was also reduced and the location of Es-β-catenin was changed from nucleus to cytoplasm in the late stage of spermatogenesis when es-kif3a was knocked down. Besides, the co-IP result demonstrated that Es-KIF3A could bind with Es-β-catenin. In summary, this study indicates that Es-KIF3A can positively regulate the Wnt/β-catenin pathway during spermatogenesis and Es-KIF3A can bind with Es-β-catenin to facilitate the nuclear translocation of Es-β-catenin. [ABSTRACT FROM AUTHOR]

The images of D'Arcy Wentworth Thompson's book "On Growth and Form" got an iconic status and became influential for biometrics and other mathematical approaches to organismic form. In particular, this is true for those of the chapter on the theory of transformation, which even has an impact on art and humanities. Based on his approach, Thompson formulated far-reaching conclusions with a partly anti-Darwinian stance. Here, we use the example of Thompson's transformation of crab carapaces to test to what degree the transformation of grids, landmarks, and shapes result in congruent images. For comparison, we applied the same series of tests to digitized carapaces of real crabs. Both approaches show similar results. Only the simple transformations show a reasonable form of congruence. In particular, the transformations to majoid spider crabs reveal a complicated transformation of grids with partly crossing lines. By contrast, the carapace of the lithodid species is relatively easily created despite the fact that it is no brachyuran, but evolved a spider crab-like shape convergently from a hermit crab ancestor. [ABSTRACT FROM AUTHOR]

Data on the record of a new prawn species for the estuarine ecosystems of the Western Caspian Sea, Macrobrachium nipponense (De Haan, 1849) (Decapoda, Crustacea, Palaemoninae), are given. Several specimens of oriental river prawn were found in the lower reaches of the Terek River, 24 km upstream of the mouth. To determine the taxonomic status of this prawn, we carried out the DNA barcoding of the COI gene. The COI gene sequence that we obtained is 99% correlated with the previously published data in the GenBank and BOLD databases. A phylogenetic analysis has revealed a genetic proximity between M. nipponense from the Terek River and the native population of prawn living in the Huaihe River in the Huaibin and Huainan regions (China). The biological features of the species suggest a high probability of its successful naturalization in the estuarine systems of the Caspian Sea, as well as its further expansion. [ABSTRACT FROM AUTHOR]

Crabs and shrimps (order Decapoda) use colours in various tasks such as foraging and mate choice. Colour vision requires at least two types of photoreceptors with different spectral sensitivities. Previous physiological studies revealed that most crabs including Scylla mud crabs have a single visual receptor system, i.e. they are colour blind. We determined colour vision by means of a behavioural experiment on hatchery-produced and wild-captured purple mud crab Scylla tranquebarica in a roofed hatchery. Adult crabs (8-10 cm carapace width) were subjected to classical conditioning to associate a food reward with a blue or a green stimulus placed among seven shades of grey. The hatchery-produced crabs learnt this task after 14 days of reward training, and thereafter distinguished blue in 27 non-reward trials, and green in 39 non-reward trials. The wild-captured crabs did so after 25 days of reward training, and distinguished green in 49 non-reward trials. These results indicated colour vision in S. tranquebarica. However, the crabs were unable to distinguish blue or green in dim light of 4.4 cd/m2 (which is slightly brighter than full moon light). The high colour vision threshold was attributed to the small optic parameters of the apposition compound eyes of S. tranquebarica. [ABSTRACT FROM AUTHOR]

The digestive system of the malacostracan crustaceans, namely the decapods, isopods, amphipods and mysids, is among the most complex organ systems of the animal kingdom serving multiple functions such as food processing, absorption and storage of nutrients, synthesis of digestive enzymes and blood proteins, detoxification of xenobiotics and osmoregulation. It is rather well investigated compared to other invertebrates because the Malacostraca include many ecological keystone species and food items for humans. The Decapoda and Peracarida share food processing with chewing and filtering structures of the stomach but differ with respect to morphology and ultrastructure of the digestive glands. In the Peracarida, the digestive glands are composed of few, relatively large lateral caeca, whereas in the Decapoda, hundreds to thousands of blindly ending tubules form a voluminous hepatopancreas. Morphogenesis and onset of functionality of the digestive system strongly depend on the mode of development. The digestive system is early developed in species with feeding planktonic larvae and appears late in species with direct lecithotrophic development. Some structures of the digestive system like the stomach ossicles are rather constant in higher taxa and are of taxonomic value, whereas others like the chewing structures are to some degree adapted to the feeding strategy. The nutrient absorbing and storing cells of the digestive glands show considerable ultrastructural variation during moult cycle, vitellogenesis and starvation. Some of the various functions of the digestive system are already assigned to specific sections of the digestive tract and cell types, but others still await precise localization. [ABSTRACT FROM AUTHOR]

The El Niño phenomenon refers to a warming of the tropical Pacific basin whose meteorological effects influence the dynamics of aquatic ecosystems around the world. Prior studies have shown that strong El Niño events are highly correlated with high rainfall episodes and high freshwater discharge into subtropical estuaries, with subsequent changes in species composition, abundance, and diversity of their biota. In this work, we evaluated the hypothesis that riverine allochthonous matter associated with the strong 2015 El Niño event is assimilated by decapod crustaceans and fishes of a southwestern Atlantic estuary. We analyzed carbon (δ13C) and nitrogen (δ15N) stable isotope ratios of primary food sources and consumers in the estuary and of riverine allochthonous matter. Our findings revealed that higher water surplus and lower salinity associated with the 2015 El Niño coincided with an increase in the number of freshwater fish species and a decrease in the number of marine- and estuarine-dependent fishes inside the estuary. In addition, most estuarine consumers had lower average δ13C values during the wet period associated with the 2015 El Niño. This seemed to reflect the assimilation of 13C-depleted riverine matter, which according to Bayesian isotope mixing models ranged from 11% (adult resident decapod crustaceans) to 60% (adult resident fishes) during the wet season. Further studies are needed to evaluate the role of El Niño events on structuring food web organization in estuaries under the influence of this climatic phenomenon, which may become more frequent and intense in a global warming scenario. [ABSTRACT FROM AUTHOR]

As a result of the commercial importance of food relevant crustaceans belonging to the order Decapoda, reliable methods for species identification are required to protect consumers against adulteration and mislabelling of crustacean products. The aim of this present study is, therefore, to compare three marker regions for their suitability to identify food relevant crustaceans of the order Decapoda: (A) the official control method in Germany for identification of crustacean species based on 16S rDNA sequences; (B) sequencing of another 16S rDNA fragment developed by Palumbi et al.; and (C)'DNA barcoding, by sequencing of the mitochondrial cytochrome c oxidase subunit 1 gene (COI). Marker region A showed some disadvantages compared to marker region C because of inadequate amplification or resulting low-quality sequences for several decapods. Marker region B showed better species identification results than marker region A, but offered no advantage compared to marker region A combined with marker region C. Marker region A is only to be preferred for species, of which the reference sequences of COI are not yet present in public sequence databases. The results of this study show that the most suitable marker region for the identification of food relevant decapods is COI and that this marker region has the potential to supplement or even replace the current official method of Germany in the official control of foodstuff. Moreover, this study shows that for certain food relevant crustacean species, there is still a lack of reference sequences. [ABSTRACT FROM AUTHOR]

The trace metal cadmium (Cd) is a toxic pollutant known to induce oxidative stress and other sublethal to lethal effects on aquatic organisms. We exposed the marine mud shrimp Austinogebia edulis to Cd concentrations of 0, 0.5, and 5 mg/kg for up to 4 days (24, 48, 72, 96 h). We studied the activity of antioxidant enzymes in the hepatopancreas, gill, and muscle of A. edulis. Antioxidant enzymes (SOD, CAT, and GPx) decreased with increasing Cd concentration and extended exposure time in these three organs of the mud shrimp A. edulis. Increasing Cd concentration led to an increase in ROS and resulted ultimately in membrane lipid peroxidation at higher Cd concentrations. Significant damage of the hepatopancreas of A. edulis was noticed at higher concentrations of Cd, showing damages like the disappearance of epithelial cell boundaries, detachment of cells from the basal lamina, cellular swelling, necrosis, and reduction of glycogen. In conclusion, Cd caused oxidative damage by reducing the activities of antioxidant enzymes and by damaging the tissue structure in major organs of the mud shrimp A. edulis. [ABSTRACT FROM AUTHOR]

Shrimps and prawns are known to generate a characteristic and pleasant aroma when cooked whole, including their shells and viscera. This study investigated this characteristic aroma of whole-roasted shrimp using Argentine red shrimp (Pleoticus muelleri). Shrimps were roasted in an oven, and the aroma changed upon the usage of whole shrimp. The aroma attributes of "roasted" and "rich" were significantly improved. We performed an analysis of volatile compounds to identify the contributors to roasted and rich aromas and identified 17 odor-active compounds. Heterocyclic compounds including pyrazines, thiazolines, and thiazoles were major contributors to the aroma of whole roasted shrimp. In aroma extract dilution analysis, 2,6-dimethylpyrazine, trimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2-acetyl-2-thiazoline, methional, 2-acetylthiazole, 2,5-dimethylpyrazine, 2,3-dimethylpyrazine, and indole were detected with higher flavor dilution factors than were other odor-active compounds. Furthermore, sensory evaluation analysis confirmed that pyrazines contributed to the roasted aroma, and thiazolines and thiazoles contributed to both the roasted and rich aromas. In conclusion, pyrazines, thiazolines, and thiazoles derived from shrimp shells or viscera were the major contributors to the characteristic aroma of whole roasted shrimp and strongly influenced the aroma impression of shrimp dishes. [ABSTRACT FROM AUTHOR]

Decapod crustaceans are faceless animals with five pairs of legs, an external skeleton and multiple nerve centres (ganglia) rather than a single brain (as in vertebrates). They include common seafood species such as crayfish, crabs, lobsters, prawns and shrimp. These characteristics make them difficult to empathise with and consequently legal protection of decapods ranges from strong (Norway and New Zealand), through circumstantial (Australia and Italy) to non-existent (in many other countries). Whether they are capable of experiencing pain depends on definitions and the requirement for absolute proof of an inherently subjective psychological experience. Yet like other animals, decapods fulfil neuroanatomical, pharmacological and behavioural criteria that are consistent with a pain response. Whether they experience stress, harm and distress is less controversial because these conditions are more measurable than the pain response. To balance animal welfare concerns with scientific merit whilst providing confidence for the growing public awareness of crustacean welfare, use of decapod crustaceans in research should require ethical review. [ABSTRACT FROM AUTHOR]

The Luoping Biota discovered from the early Middle Triassic (Anisian) Guanling Formation of southwestern China represents a fully recovered shallow marine ecosystem, marking the end point of Early Triassic biotic recovery following the end-Permian mass extinction. Contemporaneously preserved are prolific trace fossils, which offer good opportunities to understand the palaeoecology of marine invertebrates from a fully recovered shallow marine ecosystem. Here we present a newly discovered sinuous branching burrow from the fossil-bearing unit in Member II of the Guanling Formation. Several features, including the horizontal regular sinuous nature, the branching pattern, typical H-junction, and the small wavelength/amplitude ratio of these sinuous structures within the burrow systems justify assignment of these traces as Sinusichnus sinuosus, a trace possibly produced by decapod crustaceans. Close association of S. sinuosus with Rhizocorallium commune suggests a deposit-feeding strategy of these trace makers. The newly reported Anisian material from the Guanling Formation in Luoping represents first report of Sinusichnus from South China. The global record of Sinusichnus occurrence suggests that these burrows might have an older history than Early Middle Triassic. [ABSTRACT FROM AUTHOR]

The mandibles in the first zoeal stage of five species of the burrowing shrimp genera Upogebia (infraorder Gebiidea) and Nihonotrypaea (infraorder Axiidea) have been examined by scanning electron microscopy. The general shape of the mandibles in Upogebia zoeae is similar to that in Anomura larvae; in Nihonotrypaea, it is intermediate between the mandibles of anomuran and caridean shrimp larvae. The asymmetry of the mandibles, which is more pronounced in Nihonotrypaea, is confirmed. Species-specific features of the structure of the incisor process are found in three Upogebia species, while two Nihonotrypaea species almost do not differ in the mandible structure in their zoea I larvae. The morphological features of the mandibles indicate differences in the diet of Upogebia and Nihonotrypaea larvae. Under natural conditions, zoea I of the studied Nihonotrypaea species may feed on diatoms, which should be taken into account when rearing these decapod larvae in the laboratory. [ABSTRACT FROM AUTHOR]

Asthenognathus atlanticus Monod, 1932, is reported here for the first time in the area around Dieppe-Le Tréport (Normandy coast in the eastern part of the English Channel). A total of 26 specimens were collected in 2015-2016 from fine and coarse sands at water depths between 12 and 25 m. Two specimens were found in the stomach of two thornback rays Raja clavata. The eastward progression of A. atlanticus is consistent with tidal residual currents in the English Channel. The period of global warming is likely favorable for this easterly progression, and the species could reach the southern part of the North Sea in a few years. Our observations in the eastern part of the English Channel also illustrate a new commensal association between the tubicolous polychaete C. variopedatus and the crab A. atlanticus, the latter being found in a variety of soft-bottom sediments ranging from muddy to coarse sands, in agreement with reports of its presence in the Rade de Cherbourg and the Bay of Seine. [ABSTRACT FROM AUTHOR]