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In spite of considerable progress during the last few years, the fossil record of the ophiuroids, or brittle stars, is still poorly known, especially with respect to taxa restricted to specific environments. Here, we describe new ophiuroid fossils collected from an Upper Cretaceous rocky shore in Ivö Klack, southern Sweden, consisting of fully disarticulated skeletal remains retrieved from the sediments deposited between boulders and hummocks. The fossils are identified as a new species of the extant ophiocomid genus Ophiocoma. In a critical revision of the ophiocomid fossil record, we show that all fossils previously assigned to the Ophiocomidae belong to other families. Thus, the fossil record of the Ophiocomidae is currently restricted to the new species described herein, and Amphiura? gigantiformis from the Miocene of Austria which, in fact, is a species of Ophiocoma. Since recent species of Ophiocoma exclusively occur in tropical to subtropical shallow subtidal environments, our discovery of a fossil Ophiocoma species in the rocky shore sediments of Ivö therefore conforms with the previously assumed subtropical palaeotemperatures prevailing in southern Sweden during the Late Cretaceous. Most notably, it represents the northernmost occurrence of an ophiocomid recorded to date. [ABSTRACT FROM AUTHOR]

Articulated fossil ophiuroids from South America were reported for the Devonian, Cretaceous, Eocene, and Miocene. Here we report the first Jurassic record of an articulated ophiuroid from the Sierra Chacaicó Formation (early Pliensbachian-Sinemurian) in Neuquén Basin, Argentina, and discuss the taphonomic processes that allowed its preservation. The Sierra Chacaicó Formation represents the onset of the Early Jurassic extensive marine transgression in the basin. The basal section comprises shoreface and offshore Gilbert-type delta system, which was affected by hyperpycnal discharges. The middle and upper sections are represented by offshore deposits, affected by storms and eroded by hyperpycnal channel-levee systems. The ophiuroid specimen was found in levels of massive, fine, tuffaceous sandstone beds and covered by coarse sandstone containing a large amount of plant debris and organic matter. It was preserved articulated, with a complete disc and almost complete arms. Based on the microstructure of the spine-bearing lateral arm plates, the ophiuroid is assigned to Sinosura, an extinct genus of the family Ophioleucidae, widespread in the Lower Jurassic deposits of Europe but previously unknown from other parts of the world. The posture of the ophiuroid, with one arm curved distally and extended in one direction and the other four arms symmetrically oriented in the opposite direction, suggests a walking or escape movement frozen in time. This implies that the ophiuroid was buried alive by sediment thick enough to prevent successful escape. The taphonomic and sedimentologic evidence indicates that the fossil material was found in hyperpycnal deposits accumulated in offshore positions, which carried a high concentration of sediment in suspension. [ABSTRACT FROM AUTHOR]

Regeneration is a post-embryonic developmental process common in Metazoa, which, despite obvious taxa-specific differences, can often share common principles and patterns. Among these, the distalization and (proximal) intercalation model successfully describes most animal regeneration phenomena. Stellate echinoderms (Crinoidea, Asteroidea, and Ophiuroidea) are particularly practical models for regeneration studies as the proximo-distal regrowth of their "segmental" arms, including the inner "continuous" yet homologous structures, i.e. radial water canal, radial nerve cord, and somatocoel, provide a unique opportunity to investigate the existence of evolutionarily shared regenerative patterns. In the present work, we comparatively examined the anatomy of arm regeneration in four stellate echinoderm species – the crinoid Antedon mediterranea, the asteroids Echinaster sepositus and Coscinasterias tenuispina, and the ophiuroid Amphipholis squamata. We observed that in all the models the distal elements, i.e. the apical blastema of crinoids, and terminal ossicle and tube foot of asteroids and ophiuroids, form in an early stage, followed by the proximal region, which develops in the proximal-to-distal direction. In all arms, the continuous structures develop before discrete lateral structures (e.g. ossicles and tube feet), and appear to provide materials that make the subsequent development possible. Overall, the model inferred from our study is compatible with those previously proposed for other animal models that involve processes of distalization and intercalation. The evidence of shared patterns suggests that at least some overall regeneration mechanisms have ancient origins and are well conserved throughout echinoderm and animal evolution. This study could help shed light on those evolutionarily conserved principles (patterns) among metazoan regeneration. [ABSTRACT FROM AUTHOR]

Background: Echinoderms are established models in experimental and developmental biology, however genomic resources are still lacking for many species. Here, we present the draft genome of Ophioderma brevispinum, an emerging model organism in the field of regenerative biology. This new genomic resource provides a reference for experimental studies of regenerative mechanisms. Results: We report a de novo nuclear genome assembly for the brittle star O. brevispinum and annotation facilitated by the transcriptome assembly. The final assembly is 2.68 Gb in length and contains 146,703 predicted protein-coding gene models. We also report a mitochondrial genome for this species, which is 15,831 bp in length, and contains 13 protein-coding, 22 tRNAs, and 2 rRNAs genes, respectively. In addition, 29 genes of the Notch signaling pathway are identified to illustrate the practical utility of the assembly for studies of regeneration. Conclusions: The sequenced and annotated genome of O. brevispinum presented here provides the first such resource for an ophiuroid model species. Considering the remarkable regenerative capacity of this species, this genome will be an essential resource in future research efforts on molecular mechanisms regulating regeneration. [ABSTRACT FROM AUTHOR]

Gastropods of the genus Mucronalia (Eulimidae) are known ectoparasites of brittle stars (Ophiuroidea). However, the identities of host species are only known for three of some ten described species in the genus. Here, we report associations of Mucronalia snails, including one new species, with ophiuroid hosts from Japan and New Caledonia: M. spp. aff. alba with Ophiomastix annulosa, Ophiomastix mixta, and Ophiocoma cynthiae; M. sp. cf. exquisita with Amphioplus (Amphioplus) sp.; Mucronalia ryukyuensis n. sp. with Ophionereis porrecta; and Mucronalia sp. with Amphiura velox. Mucronalia ryukyuensis n. sp. is described from Okinawa, southwestern Japan. The new species is characterized by its slender shell with a large body whorl and aperture compared with other species of the genus. Among Japanese congeners, the shell of the new species is most similar to that of M. exilis, but differs in having a teleoconch with less-convex whorls, regularly increasing in diameter. The present study corroborates Warén's (1983) general rule that eulimids in a single genus parasitize hosts of the same echinoderm class, and our records suggest that closely related species of Mucronalia tend to exploit hosts of a more restricted lineage. We also briefly discuss the divergence processes of Mucronalia snails, which likely involve host shifts and geographic isolation. [ABSTRACT FROM AUTHOR]

The fossil record of the Ophiuroidea is still patchy, especially in the Cenozoic. Only four species have been described from the entire Oligocene, which is in stark contrast to the present-day diversity counting more than 2000 species. Here, we describe two new species of ophiuroid, Ophiura tankardi sp. nov. and Ophiodoris niersteinensis sp. nov., from the Lower Oligocene of the Mainz Basin. The species are based on microfossils extracted from the sieving residues of bulk sediment samples from a flush drill in Nierstein, Rhineland-Palatinate. The new species belong to extant genera and add to the poor Oligocene fossil record of the class. Based on present-day distributions, the occurrence of Ophiodoris suggests deep sublittoral to shallow bathyal palaeodepths for the Nierstein area of the Mainz Basin. [ABSTRACT FROM AUTHOR]

Rocky reefs of the northern Colombian Pacific (Chocó) are diverse ecosystems that are poorly studied. Echinoderms are one of the principal groups in these ecosystems with associations to different species, including benthic organisms in which they live and other species that use them as hosts. These relationships include fishes, sponges, seaweeds, cnidarians, polychaetes, bryozoans, crustaceans, mollusks, and other echinoderms. For this area, 22 associations were registered, including commensalism, epibionts and parasitism. This work constitutes the first report for the associations of Eucidaris thouarsii with Suberites aff. ficus, E. thouarsii with Ophiothela mirabilis, and Holothuria (Thymiosicia) impatiens with Encheliophis vermicularis. Associations of Pentaceraster cumingi with Zenopontonia soror, and Ophionereis annulata with Malmgreniella cf. variegata are new records for Colombia. This work also expands the range of hosts previously described for Ophiothela mirabilis and expands the distribution of the association between Diadema mexicanum and Echineulima cf. robusta. [ABSTRACT FROM AUTHOR]

The article focuses on research which aims to determine how the ophiuroid nervous system performs complex decision making and locomotory actions under decentralized control. Information about the results, which show that brittle star arms must be connected by the nerve ring for coordinated locomotion however information can travel bidirectionally around the nerve ring so that it circumvents the severance, is presented.

Brittle stars (Phylum Echinodermata, Class Ophiuroidea) have evolved rapid locomotion employing muscle and skeletal elements within their (usually) five arms to apply forces in a manner analogous to that of vertebrates. Inferring the inner workings of the arm has been difficult as the skeleton is internal and many of the ossicles are sub‐millimeter in size. Advances in 3D visualization and technology have made the study of movement in ophiuroids possible. We developed six virtual 3D skeletal models to demonstrate the potential range of motion of the main arm ossicles, known as vertebrae, and six virtual 3D skeletal models of non‐vertebral ossicles. These models revealed the joint center and relative position of the arm ossicles during near‐maximal range of motion. The models also provide a platform for the comparative evaluation of functional capabilities between disparate ophiuroid arm morphologies. We made observations on specimens of Ophioderma brevispina and Ophiothrix angulata. As these two taxa exemplify two major morphological categories of ophiuroid vertebrae, they provide a basis for an initial assessment of the functional consequences of these disparate vertebral morphologies. These models suggest potential differences in the structure of the intervertebral articulations in these two species, implying disparities in arm flexion mechanics. We also evaluated the differences in the range of motion between segments in the proximal and distal halves of the arm length in a specimen of O. brevispina, and found that the morphology of vertebrae in the distal portion of the arm allows for higher mobility than in the proximal portion. Our models of non‐vertebral ossicles show that they rotate further in the direction of movement than the vertebrae themselves in order to accommodate arm flexion. These findings raise doubts over previous hypotheses regarding the functional consequences of ophiuroid arm disparity. Our study demonstrates the value of integrating experimental data and visualization of articulated structures when making functional interpretations instead of relying on observations of vertebral or segmental morphology alone. This methodological framework can be applied to other ophiuroid taxa to enable comparative functional analyses. It will also facilitate biomechanical analyses of other invertebrate groups to illuminate how appendage or locomotor function evolved. [ABSTRACT FROM AUTHOR]

The peristomial plates are skeletal components of the interbrachial frame (or mouth frame), which is located below the true mouth of ophiuroids. Whilst the peristomial plates were extensively described and used as diagnostic characters by some early workers, for the past 100 years they have been largely neglected as a taxonomic resource. In this investigation the peristomial plates of 48 species representing 21 families were examined directly, and information on a further 61 species, including representatives of another eight families, was obtained from the published literature. Observations were made with regard to fragmentation state, relative size and orientation of the peristomial plates. Although fragmentation state showed little consistency at any taxonomic level, relative size and orientation segregated a group of families comprising species with relatively small, inclined peristomial plates, viz. Ophiotrichidae, Ophiopholidae, Ophiactidae, Amphiuridae and Ophiocomidae, together with a single hemieuryalid species–Ophioplocus januarii. The distribution of peristomial plate traits was strongly correlated with that of several other character states pertaining to the interbrachial frame. This supported the proposition that two major types of interbrachial frame are present in ophiuroids (designated ‘A’ and ‘B’). Current phylogenies inferred from both morphological and molecular data imply that type B is derived and has evolved independently at least twice in the orders Amphilepidida and Ophiacanthida. This represents a remarkable example of evolutionary convergence. An analysis of the distribution of all interbrachial frame character states suggested that within the Amphilepidida paedomorphosis was probably responsible for the complete reversion of the interbrachial frame to the ancestral type A condition in two families (Ophiothamnidae and Amphilepididae) of suborder Gnathophiurina and possibly responsible for varying degrees of trait reversal in the four families of suborder Ophionereidina. Such paedomorphic events may have been associated with a secondary return to the deep-sea from shallow-sea environments. [ABSTRACT FROM AUTHOR]

The brittle star Ophiothela cf. mirabilis, an ophiuroid introduced in the Atlantic, has expanded its range north to Trinidad and Tobago and south to Paraná, Brazil. By monitoring the coast of Santa Catarina, Brazil, with both recruitment plates in harbors and scuba diving, we were able to observe specimens of O. cf. mirabilis in both natural and anthropogenic habitats. This confirms its reported range extension of roughly 80 km south and emphasizes the importance of anthropogenic means for their spread and establishment. [ABSTRACT FROM AUTHOR]

Background: Brittle stars (Ophiuroidea, Echinodermata) have been increasingly used in studies of animal behavior, locomotion, regeneration, physiology, and bioluminescence. The success of these studies directly depends on good working knowledge of the ophiuroid nervous system. Results: Here, we describe the arm nervous system at different levels of organization, including the microanatomy of the radial nerve cord and peripheral nerves, ultrastructure of the neural tissue, and localization of different cell types using specific antibody markers. We standardize the nomenclature of nerves and ganglia, and provide an anatomically accurate digital 3D model of the arm nervous system as a reference for future studies. Our results helped identify several general features characteristic to the adult echinoderm nervous system, including the extensive anatomical interconnections between the ectoneural and hyponeural components, neuroepithelial organization of the central nervous system, and the supporting scaffold of the neuroepithelium formed by radial glial cells. In addition, we provide further support to the notion that the echinoderm radial glia is a complex and diverse cell population. We also tested the suitability of a range of specific cell-type markers for studies of the brittle star nervous system and established that the radial glial cells are reliably labeled with the ERG1 antibodies, whereas the best neuronal markers are acetylated tubulin, ELAV, and synaptotagmin B. The transcription factor Brn1/2/4 - a marker of neuronal progenitors - is expressed not only in neurons, but also in a subpopulation of radial glia. For the first time, we describe putative ophiuroid proprioceptors associated with the hyponeural part of the central nervous system. Conclusions: Together, our data help establish both the general principles of neural architecture common to the phylum Echinodermata and the specific ophiuroid features. [ABSTRACT FROM AUTHOR]

The worms Malmgreniella variegata has been found as commensal of Ophionereis reticulata in Florida and Belize. Here we report the association in Playa Piscina (Arapo Islands), Venezuela. [ABSTRACT FROM AUTHOR]

The distributional records of Ophiuroidea stored at the Italian National Antarctic Museum (MNA, Section of Genoa) are presented, corresponding to 1595 individuals that belong to 35 species and 17 genera. Specimens were collected in 106 different sampling stations at depths ranging from 21 to 1652 m in the framework of 14 Antarctic expeditions to the Ross Sea, one to the Antarctic Peninsula, and one to the Falkland Islands (Islas Malvinas). Three species, Amphiura joubini Koehler, 1912, Amphiura (Amphiura) angularis Lyman, 1879, and Ophiura flexibilis (Koehler, 1911), are reported as new records for the Terra Nova Bay area, whose check-list of species increases from 15 to 18 species. The determination of these three new records was based both on morphological identification and molecular analyses (COI barcoding). Some of the genetically characterised specimens were also documented through photogrammetry and micro-computed tomography and represent the first bulk of 3D models that will be available through the MNA and Sketchfab websites, both for research and educational purposes. [ABSTRACT FROM AUTHOR]

The fossil record of Paleozoic ophiuroids includes a number of forms which share striking similarities with modern relatives in terms of skeletal morphology. These so called modern-type Paleozoic ophiuroids yield an enormous potential for a better understanding of ophiuroid evolution, yet the scarcity of accurate and sufficiently detailed morphological descriptions available to date precludes any further-reaching assessments. Here, we describe an articulated ophiuroid specimen from the Late Tournaisian (early Carboniferous) of Czatkowice quarry, southern Poland, as a new species Aganaster jagiellonicus sp. nov. The good preservation of the specimen allowed for a morphological analysis at a level comparable to recent ophiuroid descriptions. It shows remarkable morphological similarities with extant former ophiolepidids Ophiomusium and Ophiosphalma. The new find thus contributes to a solid basis for future investigations on the position of the modern-type Paleozoic ophiuroid in the phylogeny of the class. [ABSTRACT FROM AUTHOR]

The fiords of southwestern New Zealand may promote the existence of genetically divergent populations as a result of geological and ecological isolation. The ophiuroidAstrobrachion constrictumlives on black coral in these fiords, and is thought to have a relatively short pelagic larval duration that may limit dispersal among populations. Samples ofA. constrictumwere collected from seven sites (four fiords) in Fiordland. Analysis of the mitochondrial COI gene using single-stranded conformational polymorphism revealed eight haplotypes, representatives of which were sequenced. These included nine variable sites, none of which were phylogenetically informative.G-test and AMOVA revealed little structuring of samples within or among fiords, but there was evidence for reduced gene flow among the most geographically separated fiords. We conclude that fiords do not house relict populations from earlier glaciations, and that little differential sorting of haplotypes has occurred in the last 10,000 years. [ABSTRACT FROM PUBLISHER]

Ophiuroids were collected during the Singapore Biodiversity Workshop at Pulau Ubin in 2012. About 520 specimens were provisionally identified and 22 species of ophiuroids recognised. Fourteen species are new to Singapore waters. [ABSTRACT FROM AUTHOR]

Background In metazoans, opsins are photosensitive proteins involved in both vision and non-visual photoreception. Echinoderms have no well-defined eyes but several opsin genes were found in the purple sea urchin (Strongylocentrotus purpuratus) genome. Molecular data are lacking for other echinoderm classes although many species are known to be light sensitive. Results In this study focused on the European brittle star Amphiura filiformis, we first highlighted a blue-green light sensitivity using a behavioural approach. We then identified 13 new putative opsin genes against eight bona fide opsin genes in the genome of S. purpuratus. Six opsins were included in the rhabdomeric opsin group (r-opsins). In addition, one putative ciliary opsin (c-opsin), showing high similarity with the c-opsin of S. purpuratus (Sp-opsin 1), one Go opsin similar to Sp-opsins 3.1 and 3.2, two basal-branch opsins similar to Sp-opsins 2 and 5, and two neuropsins similar to Sp-opsin 8, were identified. Finally, two sequences from one putative RGR opsin similar to Sp-opsin 7 were also detected. Adult arm transcriptome analysis pinpointed opsin mRNAs corresponding to one r-opsin, one neuropsin and the homologue of Sp-opsin 2. Opsin phylogeny was determined by maximum likelihood and Bayesian analyses. Using antibodies designed against c- and r-opsins from S. purpuratus, we detected putative photoreceptor cells mainly in spines and tube feet of A. filiformis, respectively. The r-opsin expression pattern is similar to the one reported in S. purpuratus with cells labelled at the tip and at the base of the tube feet. In addition, r-opsin positive cells were also identified in the radial nerve of the arm. C-opsins positive cells, expressed in pedicellariae, spines, tube feet and epidermis in S. purpuratus were observed at the level of the spine stroma in the brittle star. Conclusion Light perception in A. filiformis seems to be mediated by opsins (c- and r-) in, at least, spines, tube feet and in the radial nerve cord. Other non-visual opsin types could participate to the light perception process indicating a complex expression pattern of opsins in this infaunal brittle star. [ABSTRACT FROM AUTHOR]

Cryptic species are numerous in the marine environment. The brittle star Ophioderma longicauda is composed of six mitochondrial lineages, encompassing brooders, which form a monophyletic group, and broadcasters, from which the brooders are derived. To clarify the species limits within O. longicauda , we compared the reproductive status of the sympatric lineages L1 and L3 (defined after sequencing a portion of the mitochondrial gene COI ) during the month of May in Greece. In addition, we genotyped a nuclear marker, intron i51. Each L3 female was brooding, whereas all L1 specimens displayed full gonads, suggesting temporal pre-zygotic isolation between brooders and broadcasters. Statistical differences were found among lineages in morphology and bathymetric distribution. Finally, the intron i51 was polymorphic in L1 (60 individuals), but monomorphic in L3 (109 individuals), confirming the absence of gene flow between brooders and broadcasters. In conclusion, the broadcasting lineage L1 and the brooding lineage L3 are different biological species. [ABSTRACT FROM AUTHOR]

Brittle stars (Echinodermata: Ophiuroidea) comprise over 2,000 species, all of which inhabit marine environments and can be abundant in the deep sea. Morphological plasticity in number and shape of skeletal parts, as well as variable colors, can complicate correct species identification. Consequently, DNA sequence analysis can play an important role in species identification. In this study we compared the genetic variability of the mitochondrial cytochrome c subunit I gene (COI) and the nuclear small subunit ribosomal DNA (SSU, 18S rDNA) to morphological identification of 66 specimens of 11 species collected from the North Atlantic in Icelandic waters. Also two species delimitation tools, Automatic Barcode Gap Discovery (ABGD) and General Mixed Yule Coalescence Method (GMYC) were performed to test species hypotheses. The analysis of both gene fragments was successful to discriminate between species and provided new insights into some morphological species hypothesis. Although less divergent than COI, it is helpful to use the SSU region as a complementary fragment to the barcoding gene. [ABSTRACT FROM AUTHOR]

Glycosaminoglycans (GAGs) isolated from brittlestars, Echinodermata class Ophiuroidea, were characterized, as part of attempts to understand the evolutionary development of these polysaccharides. A population of chondroitin sulfate/dermatan sulfate (CS/DS) chains with a high overall degree of sulfation and hexuronate epimerization was the major GAG found, whereas heparan sulfate (HS) was below detection level. Enzymatic digestion with different chondroitin lyases revealed exceptionally high proportions of di- and trisulfated CS/DS disaccharides. The latter unit appears much more abundant in one of four individual species of brittlestars, Amphiura filiformis, than reported earlier in other marine invertebrates. The brittlestar CS/DS was further shown to bind to growth factors such as fibroblast growth factor 2 and to promote FGF-stimulated cell signaling in GAG-deficient cell lines in a manner similar to that of heparin. These findings point to a potential biological role for the highly sulfated invertebrate GAGs, similar to those ascribed to HS in vertebrates. [ABSTRACT FROM PUBLISHER]

Ophioderma peruana sp. n. is a new species of Ophiodermatidae, extending the distribution of the genus Ophioderma to Lobos de Afuera Island, Peru, easily distinguishable from its congeners by its peculiarly fragmented dorsal arm plates. Dense granules, rounded or polygonal cover the disc, the radial shields may be naked or completely covered by granules. A good character for recognizing this species in the field is the dorsal side of the disc which is brown with disc granules lighter cream and brown, the arms are mottled with whitish spots and the ventral part of the disc on the interradial part is brown and the radial part bright yellow. [ABSTRACT FROM AUTHOR]

Beazley, L. I., Kenchington E. L., Murillo, F. J., and Sacau, M. 2013. Deep-sea sponge grounds enhance diversity and abundance of epibenthic megafauna in the Northwest Atlantic. – ICES Journal of Marine Science, 70: .The influence of structure-forming deep-water sponge grounds on the composition, diversity, and abundance of the local epibenthic megafaunal community of the Flemish Pass area, Northwest Atlantic was statistically assessed. These habitats are considered vulnerable marine ecosystems and, therefore, warrant conservation measures to protect them from bottom fishing activities. The epibenthic megafauna were quantified from four photographic transects, three of which were located on the western slope of the Flemish Cap with an overall depth range of 444–940 m, and the fourth in the southern Flemish Pass between 1328 and 1411 m. We observed a diverse megafaunal community dominated by large numbers of ophiuroids and sponges. On the slope of the Flemish Cap, sponge grounds were dominated by axinellid and polymastid sponges, while the deeper sponge ground in the southern Flemish Pass was formed mainly by geodiids and Asconema sp. The presence of structure-forming sponges was associated with a higher biodiversity and abundance of associated megafauna compared with non-sponge habitat. The composition of megafauna significantly differed between sponge grounds and non-sponge grounds and also between different sponge morphologies. Surface chlorophyll a and near-bottom salinity were important environmental determinants in generalized linear models of megafaunal species richness and abundance. [ABSTRACT FROM PUBLISHER]

Ophiurites crinitus is a fossil brittle-star species which passed largely unnoticed since its original description. In this pa- per, we redescribe the type material of O. crinitus with the aim to put it into the context of modern ophiuroid systematics, and propose the new genus name Ophiosternle to replace the invalid Ophiurites. The re-assessed species is shown to be a member of the extant deep-sea family Ophiacanthidae, articulated fossils of which are extremely rare. It presents greatest affinities with members of the Ophioplinthaca-Ophiocamax-Ophiomitra clade, of which it most probably represents the oldest known fossil species. The depositional environment of the strata, which yielded the described specimens is interpreted as shallow, storm-influenced marine setting in the immediate vicinity of coral reefs. This contrasts with the distribution pattern of extant species of the Ophioplinthaca-Ophiocamax-Ophiomitra clade, which almost exclusively occur at depths exceeding the shelf break. [ABSTRACT FROM AUTHOR]

The genus Asteromorpha Lütken (Echinodermata: Ophiuroidea: Euryalidae: Euryalinae) is revised based on 52 specimens, including six syntypes of Asteromorpha steenstrupi, one syntype of Asteromorpha perplexum (Koehler), one syntype of Asteromorpha koehleri (Döderlein) and the holotype of Astroschema capensis Mortensen. We propose a new combination of Asteroschema capense (Euryalidae: Asteroschematinae) with the genus Asteromorpha. Consequently Asteromorpha includes four species: A. capensis, A. koehleri, A. rousseaui, and A. tenax. These four species are all redescribed. A taxonomic key to the species of the genus Asteromorpha is also provided. [ABSTRACT FROM AUTHOR]

Mast cells play a critical role in the innate immune response to bacterial infection. They internalize and kill a variety of bacteria and process antigen for presentation to T cells via MHC molecules. Although mast cell phagocytosis appears to play a significant role during bacterial infection, little is known about the proteins involved in its regulation. In this study, we demonstrate that the SNARE protein SNAP29 is involved in mast cell phagocytosis. SNAP29 is localized in the endocytic pathway and is transiently recruited to Escherichia coli (E. coli)-containing phagosomes. Interestingly, overexpression of SNAP29 significantly increases the internalization and killing of E. coli, while it does not affect mast cell exocytosis of inflammatory mediators. To our knowledge, these data are the first to demonstrate a novel function of SNAP29 in mast cell phagocytosis and have implications in protection against bacterial infection. [ABSTRACT FROM AUTHOR]

Brittle stars (Ophiuroidea, Echlnodermata) are pentaradially symmetrical echinoderms that use five multi-jointed limbs to locomote along the seafloor. Prior qualitative descriptions have claimed coordinated movements of the limbs in a manner similar to tetrapod vertebrates, but this has not been evaluated quantitatively. It is uncertain whether the ring-shaped nervous system, which lacks an anatomically defined anterior, is capable of generating rhythmic coordinated movements of multiple limbs. This study tested whether brittle stars possess distinct locomotor modes with strong inter-limb coordination as seen in limbed animals in other phyla (e.g. tetrapods and arthropods), or instead move each limb independently according to local sensory feedback. Limb tips and the body disk were digitized for 56 cycles from 13 individuals moving across sand. Despite their pentaradial anatomy, all Individuals were functionally bilateral, moving along the axis of a central limb via synchronous motions of contralateral limbs (±∼13% phase lag). Two locomotor modes were observed, distinguishable mainly by whether the central limb was directed forwards or backwards. Turning was accomplished without rotation of the body disk by defining a different limb as the center limb and shifting other limb identities correspondingly, and then continuing locomotion in the direction of the newly defined anterior. These observations support the hypothesis that, in spite of their radial body plan, brittle stars employ coordinated, bilaterally symmetrical locomotion. [ABSTRACT FROM AUTHOR]

This review presents a comprehensive overview of the current status regarding the global diversity of the echinoderm class Ophiuroidea, focussing on taxonomy and distribution patterns, with brief introduction to their anatomy, biology, phylogeny, and palaeontological history. A glossary of terms is provided. Species names and taxonomic decisions have been extracted from the literature and compiled in The World Ophiuroidea Database, part of the World Register of Marine Species (WoRMS). Ophiuroidea, with 2064 known species, are the largest class of Echinodermata. A table presents 16 families with numbers of genera and species. The largest are Amphiuridae (467), Ophiuridae (344 species) and Ophiacanthidae (319 species). A biogeographic analysis for all world oceans and all accepted species was performed, based on published distribution records. Approximately similar numbers of species were recorded from the shelf (n = 1313) and bathyal depth strata (1297). The Indo-Pacific region had the highest species richness overall (825 species) and at all depths. Adjacent regions were also relatively species rich, including the North Pacific (398), South Pacific (355) and Indian (316) due to the presence of many Indo-Pacific species that partially extended into these regions. A secondary region of enhanced species richness was found in the West Atlantic (335). Regions of relatively low species richness include the Arctic (73 species), East Atlantic (118), South America (124) and Antarctic (126). [ABSTRACT FROM AUTHOR]

This study deals with the structure of echinoderm assemblages and their relationships with the biotic and abiotic conditions in the Çanakkale Strait in 2006 and 2007. A total of 25 echinoderm species were found, 4 species of which [Amphiura securigera (Düben & Koren, 1846); Amphiura lacazei Guille, 1976; Amphiura cherbonnieri Guille, 1972; and Thyone fusus (O.F. Müller, 1776)] were new records for Turkish fauna; 1 species [Ophiopsila annulosa (M. Sars, 1859)] was new for the Turkish Strait System; and 22 species were first reports for the Çanakkale Strait. Echinocyamus pusillus (O.F. Müller, 1776), Amphipholis squamata (Delle Chiaje, 1829), and Ophiothrix fragilis (Abildgaard, 1789) were the most important species, representing 71% of the total abundance. Ophiuroids were found to be the dominant group, but asteroids also played a significant role in the echinoderm community structure. No seasonal differences were found, while finer sediments and the percentage of organic carbon (TOC) seemed to encourage echinoderm behavior. Hydrodynamism seems to be the factor regulating benthic assemblages' structure and distribution in the Çanakkale Strait. An identification key to the Mediterranean species of the genus Amphiura is provided. [ABSTRACT FROM AUTHOR]

Squamophis, a new genus of brittle star is described. Two species are included in the genus: Squamophis amamiensis (Okanishi & Fujita, 2009) from south-western Japan and Squamophis albozosteres sp. n. from north-western Australia. Squamophis gen. n. is distinguished from the other genera of the family Asteroschematidae by the following characters: each radial shield is single-layered and is completely covered by plate-shaped epidermal ossicles, and the relative length of the longest arm spine throughout the arms is as long as the length of the corresponding arm segment. Squamophis albozosteres sp. n. is distinguished from Squamophis amamiensis in having white, slightly domed, plate-shaped epidermal ossicles on the aboral side of the body, the ossicles on aboral and lateral portion of the arms form transverse rows, and the other part of aboral side of disc and basal to middle portion of arms are brown but tip of the arms are light purple. [ABSTRACT FROM AUTHOR]

This study examined echinoderm assemblages from nearshore rocky habitats for large-scale distribution patterns with specific emphasis on identifying latitudinal trends and large regional hotspots. Echinoderms were sampled from 76 globally-distributed sites within 12 ecoregions, following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). Sample-based species richness was overall low (<1-5 species per site), with a total of 32 asteroid, 18 echinoid, 21 ophiuroid, and 15 holothuroid species. Abundance and species richness in intertidal assemblages sampled with visual methods (organisms >2 cmin 1 m2 quadrats) was highest in the Caribbean ecoregions and echinoids dominated these assemblages with an average of 5 ind m-2. In contrast, intertidal echinoderm assemblages collected from clearings of 0.0625 m2 quadrats had the highest abundance and richness in the Northeast Pacific ecoregions where asteroids and holothurians dominated with an average of 14 ind 0.0625 m-2. Distinct latitudinal trends existed for abundance and richness in intertidal assemblages with declines from peaks at high northern latitudes. No latitudinal trends were found for subtidal echinoderm assemblages with either sampling technique. Latitudinal gradients appear to be superseded by regional diversity hotspots. In these hotspots echinoderm assemblages may be driven by local and regional processes, such as overall productivity and evolutionary history. We also tested a set of 14 environmental variables (six natural and eight anthropogenic) as potential drivers of echinoderm assemblages by ecoregions. The natural variables of salinity, sea-surface temperature, chlorophyll a, and primary productivity were strongly correlated with echinoderm assemblages; the anthropogenic variables of inorganic pollution and nutrient contamination also contributed to correlations. Our results indicate that nearshore echinoderm assemblages appear to be shaped by a network of environmental and ecological processes, and by the differing responses of various echinoderm taxa, making generalizations about the patterns of nearshore rocky habitat echinoderm assemblages difficult. [ABSTRACT FROM AUTHOR]

A small lot of latest Cretaceous brittlestars from the Maastrichtian type area, contained in the Binkhorst [van den Binkhorst] Collection at the Museum für Naturkunde in Berlin, is restudied and, in part, illustrated for the first time. Presumably, these thirteen specimens represent only a portion of the ophiuroid material referred to in two papers by Binkhorst van den Binkhorst, both published in 1859, because all are assignable to two species which are common only in the Nekum and Meerssen members of the type Maastrichtian, namely Felderophiura vanderhami Jagt, 1991, and Ophiomusium lux Jagt & Kutscher in Jagt, 2000. Brittlestar material from lower levels within the Maastricht Formation (i.e., Valkenburg, Gronsveld, Schiepersberg and Emael members) referred to by Binkhorst has not been traced. Alternatively, Binkhorst's original records could have been based on specimens contained in collections of his contemporaries, such as Joseph de Bosquet and Casimir Ubaghs. In most, if not all, of such cases, representatives of Ophiomusium gr. granulosum (Roemer, 1841) [sensu Jagt, 2000] are involved. Based on our own observations in the Maastricht area, Binkhorst's specimens of F. vanderhami and O. lux must have originated from the upper Meerssen Member where these two species are locally common. In fact, mostly isolated discs are preserved in the present lot, with only some retaining proximal arm portions, which suggests these were picked from sieving residues after bulk sample processing. More or less complete specimens of both species have also been collected recently, but these are confined to bedding planes. Although preservation is mediocre, diagnostic features of both F. vanderhami and O. lux are readily apparent. [ABSTRACT FROM AUTHOR]

The ophiuroid Amphipholis kochii is able to detach its central disc from the underlying oral frame in response to external stimuli. In this article we supply new observations on the microanatomy and ultrastructure of the autotomy plane, and of the juxtaligamental system which is believed to bring about connective tissue changes that underpin the detachment process. We correct previous confusion over the innervation of juxtaligamental nodes involved in disc autotomy, provide evidence that juxtaligamental cells are a population of specialized nerve cells, and present observations on changes in the ultrastructure of juxtaligamental cells during autotomy, which support the view that they are responsible for connective tissue disruption. [ABSTRACT FROM AUTHOR]

A new genus and species of Asteroidea (Echinodermata), Embolaster graffhami, Embolasteridae, n. fam., is described from the Upper Ordovician Bromide Formation of Oklahoma. Embolaster is important in part because of the presence of two similar ossicles on each interbrachial plane in the axillary position; only a single axillary is recognized in most Paleozoic asteroids. The axillary traditionally has been considered to be a part of the marginal series, although marginals are almost always paired. The two ossicles are interpreted as axillaries and the homologues of an ancestral proximal marginal pair. The odontophore, which lies distal to the mouth angle pair of most asteroids, tentatively is the homologue of the proximal axillary. Embolaster also is important because of the presence of an ossicular series between the ambulacrals and the putative adambulacrals. An extra ossicular series in this position is known from taxa traditionally assigned to the ophiuroids; however, other characters of Embolaster indicate asteroid affinities for this genus. The two ossicles lateral to and aligned with the ambulacrals in Embolaster are interpreted as homologous with the similarly arranged radial virgal series of somasteroids, although specific ossicular homologies are problematic. A part of the mouth frame structure of Embolaster is exposed, although it is tiny and therefore difficult to interpret. The mouth frame arrangement is reminiscent of those of somasteroids, with small, narrow circumorals and apparent buccal podial basins directed toward the mouth opening. Many of the striking characters of Embolaster probably are plesiomorphic; apomorphies are difficult to ascertain. [ABSTRACT FROM AUTHOR]

The article offers information on the syzygial brachials from the Upper Muschelkalk of Poland and their significance for an early origin of comatulid crinoids. It states that the syzygial brachial plates from Middle Triassic Upper Muschelkalk of the Holy Cross Mountains constitute the oldest record of syzygial articulation in crinoid arms. Moreover, four bulk interval samples from cleaned faces at four outcrops in this location were taken as subjects of the research.

Ophiopeza spinosa, a small ophiodermatid ophiuroid, is locally abundant in shallow water rubble habitat at Lizard Island, northern Great Barrier Reef, Australia. This species is a protantric hermaphrodite. The switch from reproduction as a male to a female is progressive, involving a simultaneous hermaphrodite as a transitional stage. Members of O. spinosa brood their young in the respiratory bursae. Cohorts of eggs (280 μm diameter) develop synchronously in the gonad and are spawned as a group into the bursa. Despite non-pelagic development, the larvae of O. spinosa are a vitellaria type typical of broadcast-spawning ophiodermatids, providing a link to an ancestral form with a dispersive larva. The vitellaria has prominent ciliary bands and swims in the same manner as pelagic vitellaria. In vitro, the larvae developed to the juvenile stage independent of the parent. There was no evidence of extraembryonic nutrition; a proportion of the maternal provisions were retained through metamorphosis. This is the first ophiuroid known to brood a pelagic-type vitellaria larva. Juveniles appear to leave the parent at the two- to three-arm segment stage, slightly larger than the newly settled juveniles of ophiodermatids with pelagic vitellariae. The presence of functional larvae in the bursa suggests a recent switch to the incubatory life history in O. spinosa and the possibility of a reversal back to a dispersive life history. O. spinosa have the potential to both brood and broadcast their young. [ABSTRACT FROM AUTHOR]

“Babysitting” symbioses between brittle star species involve juveniles of one species and adults of another. During this phenomenon, reported from many localities in the Indo-Pacific Ocean, juveniles are attached to the disk or lie in the bursa of the adults. The symbiosis between members of Ophiomastix venosa and their host, Ophiocoma scolopendrina, was investigated on the Great Barrier Reef of Toliara (Madagascar) during a 14-month period. The population of O. scolopendrina only occurs on rocky spurs that frequently emerge at low tide, while the population of O. venosa lies in adjacent surge channels that are always immersed. Only juveniles of O. venosa associated with adults of O. scolopendrina may occur on the rocky spurs. Analyses conducted on the populations of the two species showed that (1) the symbiosis is facultative and that symbiotic juveniles migrate into the channels when they reach a disc diameter of 6 mm, and (2) recruitment in the channels occurs in April. Host choice experiments, Y-tube experiments, and experiments assessing the resistance of the ophiuroids to air-drying were conducted in the laboratory. The experiments clearly demonstrated that (1) symbiotic juveniles of O. venosa specifically recognize adults of O. scolopendrina, while free juveniles of the same size do not, and (2) juveniles of O. venosa would not survive air-drying conditions similar to those observed on the spurs at low tides if they were not in symbiosis with adults of O. scolopendrina. [ABSTRACT FROM AUTHOR]

The importance of interannual variation in deep-sea abundances is now becoming recognized. There is, however, relatively little known about what processes dominate the observed fluctuations. The abundance and size distribution of the megabenthos have been examined here using a towed camera system at a deep-sea station in the northeast Pacific (Station M) from 1989 to 2004. This 16-year study included 52 roughly seasonal transects averaging 1.2 km in length with over 35600 photographic frames analyzed. Mobile epibenthic megafauna at 4100 m depth have exhibited interannual scale changes in abundance from one to three orders of magnitude. Increases in abundance have now been significantly linked to decreases in mean body size, suggesting that accruals in abundance probably result from the recruitment of young individuals. Examinations of size-frequency histograms indicate several possible recruitment events. Shifts in size-frequency distributions were also used to make basic estimations of individual growth rates from 1 to 6 mm/month, depending on the taxon. Regional intensification in reproduction followed by recruitment within the study area could explain the majority of observed accruals in abundance. Although some adult migration is certainly probable in accounting for local variation in abundances, the slow movements of benthic life stages restrict regional migrations for most taxa. Negative competitive interactions and survivorship may explain the precipitous declines of some taxa. This and other studies have shown that abundances from protozoans to large benthic invertebrates and fishes all have undergone significant fluctuations in abundance at Station M over periods of weeks to years. [ABSTRACT FROM AUTHOR]

Evolutionary change from planktotrophic to lecithotrophic development in echinoderms is closely tied to an increase in maternal provisioning. We provide the first data on the major energetic constituents in the eggs of two ophiuroids, the planktotroph Ophionereis fasciata (egg diameter 103 µm) and the lecithotroph O. schayeri (egg diameter 248 µm), to document changes in maternal investment associated with the switch to lecithotrophy in O. schayeri. Lipid classes in the eggs of the two species did not differ except for the presence of small amounts of wax esters in the eggs of O. schayeri. Production of a large egg in O. schayeri is mostly due to enhanced deposition of one energy-storage lipid, triglyceride. The eggs of O. schayeri are not simply scaled-up versions of the ancestral-type eggs of O. fasciata. The relationship between lipid and protein content and egg volume conformed to the relationship previously established for echinoderm eggs. Surprisingly, total lipid and protein data for the eggs of 0. schayeri grouped with data for the eggs of planktotrophic echinoderms. The eggs of 0. schayeri are small compared with those of other echinoderms with lecithotrophic development, and their energetic contents may approach the minimum provisions necessary to permit development without feeding. [ABSTRACT FROM AUTHOR]

Lapworthura lehmanni, a new species of ophiuroid, is described from four specimens from the Lower Devonian Hunsrück Slate of Germany. It is the only known ophiuroid in the Hunsrück Slate with paired but unfused ambulacrals, and it exhibits unique rows of spine-bearing dorsal arm ossicles. The genus Lapworthura Gregory was previously known only from the Ordovician of Scotland and the Silurian of England and Australia. [ABSTRACT FROM AUTHOR]

Abstract: The Permian–Triassic mass extinction interval was an important time in the evolutionary history of the echinoderms. Details of the extinction and, in particular the immediate post-extinction recovery in the Early Triassic, are seldom addressed because of a perception that the Permian–Triassic echinoderm fossil record is too poor. However, only the Holothuroidea and Asteroidea lack any Early Triassic fossil representatives. Even in these groups, details of the extinction and recovery can be inferred from recent cladistic analyses. The Holothuroidea are unique amongst the echinoderms in showing no family level extinction through the Permian–Triassic interval, possibly due to their deposit-feeding lifestyle. In contrast, the Echinoidea, Crinoidea and probably the Asteroidea underwent severe evolutionary bottlenecks during that time. In the echinoids, significant post-Permian radiation occurred from the Late Triassic (Carnian), although it may have begun in the Early Triassic. In the Crinoidea, fossil diversity increases dramatically from the Late Ladinian, although cladistic analyses suggest that initial diversification took place in the Earliest Triassic (Induan). Many undescribed crinoid remains from Lower Triassic strata worldwide also imply that the post-Permian radiation in this group may have been more rapid than currently thought. Locally in the Spathian, crinoid ossicles may approach rock-building densities. The presence of at least seven Early Triassic fossil ophiuroid species may indicate rapid post-Permian radiation in the Ophiuroidea, although the higher level affinities of these taxa are presently unresolved and the Late Permian record is poorly known. Ophiuroid remains are the most diverse echinoderm fossils during the Early Triassic, comprising both complete body fossils and disarticulated ossicles. Holothuroids possibly radiated in the Early Triassic, but current evidence from cladistic analysis favours a largely Anisian age for the post-Permian radiation in this group. All known Early Triassic echinoderms were small-sized animals that inhabited very shallow, oxygenated, low palaeolatitude environments within wave base. To cite this article: R. Twitchett, T. Oji, C. R. Palevol 4 (2005) . [Copyright &y& Elsevier]

Abstract: Early embryogenesis has been examined experimentally in several echinoderm and hemichordate classes. Although these studies suggest that the mechanisms which underlie regional specification have been highly conserved within the echinoderm + hemichordate clade, nothing is known about these mechanisms in several other echinoderm classes, including the Ophiuroidea. In this study, early embryogenesis was examined in a very little studied animal, the ophiuroid Ophiopholis aculeata. In O. aculeata, the first two cleavage planes do not coincide with the animal–vegetal axis but rather form approximately 45° off this axis. A fate map of the early embryo was constructed using microinjected lineage tracers. Most significantly, this fate map indicates that there is a major segregation of ectodermal from endomesodermal fates at first cleavage. The distribution of developmental potential in the early embryo was also examined by isolating different regions of the early embryo and following these isolates though larval development. These analyses indicate that endomesodermal developmental potential segregates unequally at first, second, and third cleavage in O. aculeata. These results provide insight into the mechanisms of regional specification in O. aculeata and yield new material for the study of the evolution of echinoderm development. [Copyright &y& Elsevier]

In ophiuroids, bioluminescence is under nervous control. Previous studies have shown that acetylcholine is the main neurotransmitter triggering light emission in Amphipholis squamata and Amphiura filiformis. By contrast, none of the neurotransmitters tested so far induced luminescence in two other ophiuroid species, Ophiopsila aranea and Ophiopsila californica. The aim of this work was thus to investigate the putative involvement of two biogenic amines, tryptamine and octopamine, in light emission of three ophiuroid species. A. filiformis responds to both tryptamine and octopamine, mainly on its arm segments, while O. californica only responds to tryptamine stimulation. By contrast, tryptamine and octopamine do not seem to be involved in O. aranea luminescence control since none of these substances induced light emission in this species. The synergic effects of several other drugs with tryptamine and octopamine were also tested. [ABSTRACT FROM AUTHOR]

Presents a study which examined the fate of the larval nervous system during metamorphosis in the ophiuroid Ophiactis resiliens using antibodies against the echinoderm-specific neuropeptide S1 and against serotonin (5HT). Organization and structure of the larval nervous system of many echinoderms; Role of 5HT in larval development; Methods used in the study; Results.

Presents a study which determined the effects of variable water motion on patterns of regeneration in the subtidal burrowing brittlestar Hemipholis elongata. Factor that contributes to the regenerative plasticity of echinoderm skeletons; Definition of phenotypic plasticity; Results of the study.

Deals with a study which reported that certain single calcite crystals used by brittlestars for skeletal construction are also a component of specialized photosensory organs. Responses of echinoderms to light intensity; Comparison between the skeletal structure and appearance of two species of brittlestars; Effect of the skeletal structure of the brittlestars' dorsal arm plates on their sensitivity to light.

Ophioscolex glacialis Müller and Troschel, 1840 (Ophiuroidea: Ophiomyxidae) was registered for first time off the Brazilian coast, from the Campos Basin of Rio de Janeiro, Brazil. The specimen was sampled during a environmental monitoring. [ABSTRACT FROM AUTHOR]