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Eulimidae is a prominent group within the class Gastropoda, comprising 1087 species that have developed specialised symbiotic relationships with all extant echinoderm classes. At least 47 species of eulimids can be found in the waters of Vietnam. Representatives of the genus Pulicicochlea, the species Vitreobalcis tripneusticola, and four new undescribed species were observed for the first time. In this study, we update the existing checklists of Vietnamese eulimids, emphasising the use of molecular barcoding to determine the phylogenetic relationships among the collected species. The classical taxonomy of molluscs relies heavily on the morphology of the shell and radula. The family Eulimidae presents challenges as in many species these features are poorly developed, and molecular phylogenetic methods have proven to be more informative for the taxonomy and systematics of this family. To understand the evolutionary pathways in Eulimidae, we constructed a COI-based phylogenetic tree, which included original sequences primarily from Vietnam and all available sequences for Eulimidae from GenBank. The newly obtained genetic information is crucial for enhancing our understanding of this family of gastropod mollusсs, as well as for any future revisions that may be necessary. [ABSTRACT FROM AUTHOR]

The Pliensbachian (Lower Jurassic) age-based Lower Marly Limestone Formation of the Moulay Idriss Zerhoun area (Morocco) and the Ain Ouarka Formation of the Ksour Mountains (Algeria) have yielded rare crinoids. Although crinoids have previously been described from the Jurassic of Algeria, their Pliensbachian occurrence is being reported here for the first time. On the other hand, one isocrinid taxa [Terocrinus subsulcatus (Münster in Goldfuss)] was also recorded from the Pliensbachian strata of Morocco. Additionally, now, from both Morocco and Algeria, Seirocrinus subangularis (Miller), belonging to the family Pentacrinitidae, is documented. This is a cosmopolitan and pseudoplaktonic crinoid species that is well-known from Asia, Europe, and North America. The taxonomic evaluation of the genus Seirocrinus is provided. The present records from Algeria and Morocco are the first finds of Seirocrinus from the African continent. Ticinocrinus moroccoensis sp. nov. represented by a cup of a rare cyrtocrinid (Cyrtocrinida) is associated with S. subangularis from Morocco. Globally, this is the second record of the genus; the first Ticinocrinus being described from the Pliensbachian of Switzerland. Thus, the present records from Morocco and Algeria are also the oldest cyrtocrinids from the southern margin of the Tethys. [ABSTRACT FROM AUTHOR]

Dorometra Clark, 1917 (Comatulida: Antedonidae) is an Indo-Pacific genus of small-sized cryptic feather stars currently comprising nine species. The monophyly of this crinoid genus has been widely questioned, although only few studies have investigated the phylogeny of Antedonidae in depth. In this study we used an integrated approach combining molecular phylogenetic, morphology, and multivariate analyses to clarify the taxonomic placement of the genus Dorometra within family Antedonidae. Eight of the nine known species of the genus collected from Australia to the Sea of Japan were included in analyses. Phylogenetic analyses using sequences from two mitochondrial (COI, 16S) and one nuclear (28S) genes demonstrate that Dorometra is polyphyletic, and its species are divided into three main clades, which are spread within other Antedonidae. As a result, we herein describe Nesometra gen. nov. Four different species delimitation methods on single and multi-locus alignments also showed higher diversity than previously thought. In particular, our results highlighted the presence of cryptic diversity within the species Dorometra nana (Hartlaub, 1890) in geographically close localities within southern Japan. By multivariate analysis of morphological matrix, we confirmed the homoplasy and plasticity of the taxonomic characters used in the description of Dorometra species, providing a path forward for the general taxonomic revision of this genus and of Antedonidae and related families. [ABSTRACT FROM AUTHOR]

Various ecosystems of the Gulf of Mexico (GoM) may be impacted by the present increase in offshore oil exploitation. To identify future changes caused by this activity, we assessed the structure of the megabenthos community in the Perdido Fold Belt (PFB) and its relationships with environmental variables, hydrocarbons, and heavy metals. To achieve this, biological and sediment samples were obtained during the surveys Perdido II (PII) and Perdido III (PIII). 325.75 103 ind km−2 and 582.34 kg AFDW km−2 were collected, distributed in 110 species. Crustaceans and echinoderms comprised more than 70% of the total abundance and biomass. The most abundant species were Astropecten cingulatus Sladen, 1883, Callinectes sapidus Rathbun, 1896, Astropecten duplicatus Gray, 1840, and Penaeus aztecus (Ives, 1891) (12.2 103 ≤ ind Km−2 ≤ 59.4 103). They also had the greatest biomass contribution (16.8 ≤ kg AFDW km−2 ≤ 192.2). BIOENV test showed the influence of depth (Z), salinity, dissolved oxygen (DO), Acenaphthylene (Acy), Fluoranthene (Flu), n-C12, n-C37, and nickel (Ni) on the community structure. Recruitment and trawling also influenced the abundance and biomass values. Despite Z defines the environmental gradient, the hydrocarbon concentration gradient within the shelf areas makes it a good candidate for developing monitoring programmes. [ABSTRACT FROM AUTHOR]

Seawater temperature, oxygen, salinity and pH are important abiotic factors, changes in which can generate stress in marine organisms. Subtidal and intertidal species, such as the sand dollar Dendraster excentricus, are daily exposed to stressors against which they have developed survival mechanisms to face environmental challenges. Analysing the expression of some key genes in response to stress factors due to changes in temperature and pH, especially in the early stages of development, opens a window of knowledge on the effect that these stressors have on benthic marine organisms. In the present work larvae and post-larvae of D. excentricus were exposed to high temperature and low pH scenarios. Survival, size and gene expression of five genes, involved in both stress response (hsp70 IV and hsp90 beta-like) and biomineralization for skeletogenesis (sm29, sm30A, carbonic anhydrase 14-like and mitochondrial proton/calcium exchanger protein LOC575637), were analysed in 4-, 6-, 8-arms, competent larvae and post-larvae. Survival of stressed larvae and post-larvae presented a significant decrease, up to 37% in some stages. A size reduction of almost 30 μm was observed when larvae were exposed to stressful conditions, except in competent larvae and in post-larvae where no significant changes were detected. After stress treatments, transcripts of hsp90 beta-like were up-regulated in all larval stages but hsp70 IV transcripts were not. Under tested stressful conditions sm29 and sm30A expression was down-regulated in larvae and post-larvae, while carbonic anhydrase 14-like and LOC575637 expressions were up-regulated. It is evident that tolerance to changes in seawater temperature and pH has a direct effect on metabolic functions of D. excentricus larvae and post-larvae, which depends on the developmental stage. If laboratory results are extrapolated to marine ecosystems, it is possible that populations of this structuring organism may be disturbed with subsequent damage to ecosystem balance, until resilient organisms acclimatize and adapt to their changing habitats. [ABSTRACT FROM AUTHOR]

This paper presents nine new records of brittle stars for the Indian waters, collected between 49 and 957 m depths in the Arabian Sea, Bay of Bengal and Andaman Sea. Of these, Ophiolepis cardioplax and Ophiopsammus aequalis are being reported for the first time from the Indian Ocean, while Astrothorax waitei, Amphiophiura insolita, Ophialcaea tuberculosa and Ophioplocus declinans are new records for the northern Indian Ocean. Three other species – Amphiura (Amphiura) dejectoides, Amphiura (Amphiura) uncinata and Ophiopeza spinosa are recorded from nearby areas but are being reported for the first time from the Indian waters. Indophioderma ganapatii, described from Agatti Island, Lakshadweep is synonymized with Ophiopeza spinosa. The nine species described in this paper include several that have not been adequately described in literature or have rarely been documented at all. [ABSTRACT FROM AUTHOR]

Ophioderma appressum is a common and abundant ophiuroid species in tropical reef communities. Nevertheless, few studies analyse and describe its biology. In this paper, we evaluate and describe the diet of this species collected at Seixas reefs, João Pessoa, Brazil. Monthly diurnal samples were obtained between September 2018 and July 2019. In total, 143 individuals were analysed. The recorded diet was variable and consisted of 24 taxa and two additional items. Most material represented unidentifiable and/or digested remains, foraminiferans, crustacean fragments, and sediment particles, indicating omnivory. The number of individuals with stomach contents varied along the year (from two to 13 specimens per month). There was also significant temporal variation in the composition of the stomach contents. The months September 2018, May 2019 and June 2019 had the highest variety of items during the study. Our results suggest generalist and opportunistic feeding behaviour and highlight the role of O. appressum as an active predator on prey of diverse taxa and body size. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine: (1) salinity that maximizes arm regeneration in the starfish Luidia clathrata; and (2) if low food consumption or low salinity is the cause of the reduced rate of arm regeneration seen at low salinities.. An estimated salinity of 33 g kg−1 produced maximum regeneration of two arms in L. clathrata. This salinity is typically greater than that found in bays that are the usual habitat for the species. Equivalent food consumption by L. clathrata in salinities of 20 g kg−1 and 30 g kg−1 resulted in greater regeneration in salinity of 30 g kg−1, suggesting lower food consumption at low salinities is not the primary reason for lower regeneration. Higher food consumption compared to lower food consumption, both tested in salinity of 30 g kg−1, did not increase regeneration, but resulted in more storage of energy in the pyloric caeca. [ABSTRACT FROM AUTHOR]

The sea urchin Centrostephanus longispinus rubicingulus was rediscovered on the continental shelf of Brazil. The subspecies was merely recorded in 1955, when Bernasconi described Centrostephanus besnardi (a synonym of C. longispinus rubicingulus), on the basis of two specimens collected at Trindade Island (State of Espírito Santo). This is the first record of this subspecies for northeastern Brazil (State of Rio Grande do Norte). A description is provided, along with comments on morphology and synonymy, illustrations of diagnostic characters and, for the first time, SEM figures of the pedicellariae of C. longispinus rubicingulus. An extended list of synonyms for the genus and species is included. This record raises the number of echinoids known from Northeastern Brazil to 32 species. [ABSTRACT FROM AUTHOR]

The sea urchin,Echinometra lucunter, is consumed in restaurants in Europe and Asia for high prices. This study evaluated the use of the essential oil ofLippia alba(EOL) as a sedative and anesthetic in this sea urchin. Different EOL concentrations were tested (50, 100 and 150 μL L−1), in addition to a group that received ethanol and a control group. After the anesthesia and recovery from the different treatments, the coelomic fluid, gonads and intestine were collected for the analysis of oxidative stress parameters. The highest concentration tested (150 μL L−1) was determined to be the optimal concentration for anesthesia. Results suggest that EOL improved the response to oxidative stress, since a lower level of thiobarbituric acid-reactive substances and greater superoxide dismutase and catalase activities were observed in the coelomic fluid andE. lucuntergonads, making the EOL a promising anesthetic for sea urchins. [ABSTRACT FROM AUTHOR]

Gorgonocephalid ophiuroids, or basket stars, reside in diverse ecosystems of all oceans, but there is limited information on their basic ecology worldwide; therefore, this study provides the first detailed numerical analysis published to date of the abundances and spatial distributions of gorgonocephalids from the eastern Pacific Ocean. We analysed the relevance of geography (latitude, longitude), oceanographic factors (temperature, chlorophyllaconcentration) and bottom type (coral, rock, sand, fleshy algae, coralline algae and turf) on the abundances ofAstrocaneum spinosumandAstrodictyum panamensein Los Angeles Bay, Mexico (29°N, 113°W), in 2006–2007. Depth did not influence the number of individuals per census, but an elevated chlorophyllaconcentration resulted in a higher abundance during the autumn (possibly the reproductive season ofAstrodictyum panamenseandAstrocaneum spinosum). The abundances of both species were positively linked to the presence of rocky bottoms and decreased in sandy areas. Additionally, the presence of live coral favoured the occurrence ofAstrodictyum panamense, while high macroalgal cover decreased its abundance. The spatial distributions of both ophiuroids were aggregated at most sites, and they were always associated with different species of octocorals, which are abundant in the area.Astrocaneum spinosumis considered among the 30 most important invertebrates in the aquarium trade in Mexico; therefore, its permanence in the study area could be affected by excessive extractions. [ABSTRACT FROM PUBLISHER]

Drilling predation of cassid gastropods (tonnacean) on echinoids is common in marine environments but is rarely documented. Tests of the minute clypeasteroidEchinocyamus pusillusOF Müller (1776) were collected from the Mediterranean Sea (Isola del Giglio, Italy). Besides general morphology, features pertaining to the morphology and distribution of predatory boreholes were examined. Furthermore, borehole frequencies among different samples sites were compared. Cassid gastropods are assumed to be the originators of the boreholes. A total of 1061 tests were analysed for drilling rates with 15.3% drilled with predominantly single boreholes. The borehole morphology is strongly affected by the microstructure of the skeleton; the borehole outline is irregular if drilled within areas where ambulacral pores are present. Vertical borehole morphology is influenced by stereom density. The size frequencies of non-drilled and drilled specimens show significant differences. Comparisons of borehole size with test size show only a low correlation between predator and prey size. The distribution of boreholes shows a high site selectivity of the predator for the aboral side of the test and the petalodium. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) contained in commercial products are released and enter into the aquatic ecosystem, posing serious possible risks to the environment and affecting the food chain. Therefore, investigating the potential toxicity of NPs on aquatic organisms has become an important issue. This study assessed the toxicity and trophic transfer of metal oxide NPs from marine microalgae (Cricosphaera elongata) to the larvae of the sea urchinParacentrotus lividus. Larvae (24 h old) were fed on 2000 cell mL−1 48 h of microalgae contaminated with 5 mg L−1of several metal oxide NPs (SiO2, SnO2, CeO2, Fe3O4) for 15 days. Larval viability and development were monitored from the 4-arm stage to the 8-arm pluteus stage. A significant decrease in survival was observed in larvae fed with microalgae exposed to SiO2and CeO2NPs. Abnormal development, characterised by skeletal degeneration and altered rudiment growth, was observed in all larvae fed with contaminated NP algae. Our findings revealed that SiO2and CeO2NPs exerted a toxic effect in the trophic interaction analysed, by reducing sea urchin larval viability, and all metal oxide NPs induced toxicological effects. In conclusion, metal oxide NPs may enter the food chain and become bioavailable for marine organisms, affecting their development. [ABSTRACT FROM PUBLISHER]

Nutrition is a major factor governing early development of sea urchins. The morphological development and survival ofTripneustes gratillalarvae, from field-collected urchins, was investigated from two separate feeding trials under different feeding regimes. MicroalgaeIsochrysissp.,Pavlova lutheriandChaetoceros muelleriwere tested as feed in May 2010 andTetraselmis suecica,Skeletonema pseudocostatumandC. muelleriwere tested in September 2010. Morphometric measurements of post-oral arm (PO), total width, total length, stomach length and mid-body line (MBL) were recorded every second day. In May, larvae fedPavlovadied after 23 days and did not reach competence. Larvae grew significantly better onChaetocerosandIsochrysis, reaching competence on day 16 and 18 respectively, and had survival rates of 5.12% and 13.8% respectively. In the September trial, larvae fedTetraselmisdied by day 9, whereas larvae fedSkeletonemaandChaetocerosreached competence by day 22. Survival rates forSkeletonemaandChaetoceroswere 2.14% and 2.3% respectively. There was a significant difference in the body profile (PO:MBL) between feed treatments at day 8 in both trials. The study suggests thatC. muelleri,S. pseudocostatumandIsochrysissp. are all suitable feeds for rearingT. gratillalarvae. [ABSTRACT FROM AUTHOR]

Shellfish aquaculture is a widespread activity in the Italian peninsula. However, only two bivalve species are mainly cultured along the coastline of that country: the Mediterranean mussel Mytilus galloprovincialis and the Manila clam Venerupis philippinarum (Ruditapes philippinarum). By contrast, just a few other mollusc species of commercial interest are scarcely reared at a small-scale level. After analysing the current status of Italian shellfish production, this paper reports and discusses the potential for culturing several different invertebrate species [i.e., the European flat oyster Ostrea edulis, the grooved carpet shell Venerupis decussata (Ruditapes decussatus), the razor clams Ensis minor and Solen marginatus, the cephalopod Octopus vulgaris, and the purple sea urchin Paracentrotus lividus] in this country. In addition, a detailed overview of the progress made in aquacultural techniques for these species in the Mediterranean basin is presented, highlighting the most relevant bottlenecks and the way forward to shift from the experimental to the aquaculture phase. Finally, an outlook of the main economic and environmental benefits arising from these shellfish culture practices is also given. [ABSTRACT FROM AUTHOR]

Research on the involvement of retroelements in developmental processes has been gaining momentum recently; however, most of the studies published so far have been focused on embryonic development. This commentary presents two recent papers, which document significant changes in transcriptional activity of retroelements in two different model systems, salamander limb regeneration and regeneration of radial organs in the sea cucumber Holothuria glaberrima. We hypothesize that transcriptional activity of the retrotransposons can be specifically controlled by the host and may play some hitherto unrecognized role in regeneration. [ABSTRACT FROM AUTHOR]

A Middle Cambrian (Series 3, Stage 5) echinoderm assemblage is described from the uppermost part of the Henson Gletscher Formation based on disarticulated material. This represents the first detailed echinoderm report from the Cambrian of North Greenland and one of the most diverse for that time. Recovered ossicles include a morphotype continuum between various biserial (brachiolar) and uniserial (“brachial”) plates from pelmatozoan feeding appendages along with thecal insertion plates, pelmatozoan holomeric and the oldest known polymeric stem elements and holdfasts. Ambulacral flooring plates from two different edrioasteroids are also described. This assemblage illustrates a high plasticity and disparity in early echinoderm stem and feeding appendages, thereby placing stress on the usual definitions of blastozoans and crinozoans, generally considered as two pelmatozoan subphyla. Along with previous studies, it also raises the question as to how early echinoderms responded to the Agronomic Revolution (Substrate Revolution). Echinoderm remains first appear during Cambrian Series 2, Stage 3, well after the Substrate Revolution had affected the first few centimetres of substrate used by this low-level tiering animals to stabilize themselves. Contrary to previous ideas, it is suggested that echinoderms evolved quickly and in a nonlinear way in response to the abrupt establishment of a mosaic of substrate types during the early Cambrian. Finally, this study highlights the primary importance of disarticulated elements in the elucidation of the early evolution, diversity and disparity of the earliest echinoderms. Such elements are much more common and always appear earlier in the geological record than the complete articulated specimens on which echinoderm studies generally focus despite the taphonomic biases which often characterize their preservation. [ABSTRACT FROM AUTHOR]

In echinoderms, the SALMFamide neuropeptides sharing the SxL/FxFamide motif seem widespread throughout the phylum and may be important signalling molecules that mediate various physiological functions. Recent identification of S1 and its analogues, MagS3 and MagS4, along with the S2 analogue, MagS2 from the starfish Marthasterias glacialis, indicated that SALMFamides in the class Asteroidea are more diverse than previously thought. Further, isolation of the neuropeptides from the radial nerve cord and studies on pharmacological actions of the neuropeptides on the cardiac stomach warrant studies on the tissue distributions of these peptides in both the nervous and digestive systems. In the present study, antisera raised against an S1 analogue, KYSALMFamide, and an S2 analogue, KYSGLTFamide, were used to localize the distribution patterns of the S1- and S2-like immunoreactivities (S1-IR/S2-IR) in the nervous and digestive systems of the starfish. In the nervous system, cell bodies in the ectoneural part were immunostained for both S1 and S2 peptides, while in the digestive system, the basi-epithelial plexus and mucosal cell bodies were immunoreactive. These immunocytochemical data support the notion that the SALMFamides may play a neuroendocrine role in mediating feeding behaviour of the starfish. Further studies including identification of peptide binding sites and differential expression pattern of mRNAs encoding the peptides are required to elucidate their physiological functions. [ABSTRACT FROM AUTHOR]

Sea cucumbers are now a global product known by the Chinese as 'beche-de-mer,' 'trepang,' or 'haisom' and are almost unexploited resources in the Mediterranean region. They are currently harvested in the Mediterranean region and exported from Turkey, and the sea cucumber species is currently the most expensive seafood in Catalonia and the Balearic Islands. Considered a delicacy in many Asian countries, there is also growing interest in their medicinal and nutraceutical value. Their successful utilization in the Mediterranean Sea will require continued refinement of aquaculture techniques and development of processes for enhancing the scale of production. Even though the majority of Mediterranean species are not considered high-value products, it is clear that the future of sea cucumber farming has interesting lucrative potential in the Mediterranean and that turning sea cucumbers into aquaculture value-added products could have profitable economic benefits in this region. [ABSTRACT FROM AUTHOR]

Ctenocystoids are a poorly understood group of fossil deuterostomes, with little known about their morphology, palaeobiology or affinities. A three-dimensional specimen of the ctenocystoid Ctenocystis utahensis from the Middle Cambrian Spence Shale (western USA) was imaged using X-ray microtomography and digitally reconstructed. This allowed the species to be described in greater detail than previously possible, providing a number of morphofunctional insights. Two openings are identified: (i) an anterior opening controlled by moveable plates in the distinctive ctenoid apparatus and (ii) a wide posterior periproct. A putative third body opening (hydropore and/or gonopore) is not present, contrary to previous reconstructions. Ctenocystis utahensis was most probably epibenthic, facing into water currents during life. Suspended food particles entered paired lateral grooves within the ctenoid apparatus through gaps between neighbouring ctenoid plates; when the ctenoid apparatus was open, material could pass from these lateral grooves to an internal chamber, which led into the main body cavity. Our reconstruction demonstrates that the plates of the ctenoid apparatus and the lateral feeding grooves are not homologous with paired brachioles, refuting suggestions that ctenocystoids are derived blastozoans. Instead, it is probable that ctenocystoids are basal stem-group echinoderms, sharing several plesiomorphies (a bilateral body plan, pharyngeal gill slits and a paired water vascular system) with the latest common ancestor of echinoderms plus hemichordates. Reconstructing the anatomy of ctenocystoids in three-dimensions is critical to a full understanding of their palaeobiology and phylogenetic position. [ABSTRACT FROM AUTHOR]

Collections of echinoderms were made from the intertidal, lagoon and reef slopes of Rodrigues over a period of 3 weeks in September to October, 2001. A total of 74 species are reported here, including three species of Crinoidea, 10 species of Asteroidea, 17 species of Ophiuroidea, 15 species of Echinoidea and 29 species of Holothurioidea. These findings include 10 new records for the Mascarene Islands (Réunion, Mauritius and Rodrigues), four species (two in the asteroid genus ' Asterina ', one in the ophiuroid genus Amphioplus and one species in the holothurioid genus Actinopyga ) that remain unnamed due to the need to clarify unresolved taxonomic issues, and one species of crinoid which could not be identified because only the distal parts of four arms were collected. In the dendrochirotid holothurioid family Psolidae, the little-known species Psolus appendiculatus (de Blainville) 1821 , P. boholensis Semper, 1868 and P. complanatus Semper, 1868 are referred to the genus Psolidium Ludwig, 1887. Despite its seniority, P. appendiculatus is treated as a (senior) synonym of the better known and described species Psolidium ornatum (Perrier, 1893). In the dendrochirotid holothurioid family Phyllophoridae, Thyonidiella cherbonnieri nom. nov. is proposed for misidentified specimens of Semperiella tenera (Ludwig, 1875) in the western Indian Ocean, and Semperiella Heding and Panning, 1954 is reduced to the synonymy of Thyonidiella Heding and Panning, 1954 . In the apodid holothurioid family Chiridotidae the species Chiridota eximia Haacke, 1880 is reduced to the synonymy of C. rigida Semper, 1868. Given the small size of the area of shallow water around Rodrigues that has been sampled, the relatively small range of marine habitats present and the geographic isolation, this is an impressive diversity. The biogeography of the 69 identified species of Rodrigues is discussed. [ABSTRACT FROM AUTHOR]

An annotated checklist is presented of echinoderm taxa recorded from around the Svalbard and Franz Josef Land archipelagos and adjacent area of the continental slope, to depths up to 3000 m. In total, 81 species are listed, together with referenced information on taxonomic synonymies, biogeographical and depth distributions. [ABSTRACT FROM AUTHOR]