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Brittle stars exhibit a very remarkable taxis in electric field. All the arms become oriented to the cathode and the animal physically approaches to this electrode

The ultrastructure of the cuticle, fibrillar glands and stäbchen (see Reichensperger 1908) of the arm spines of the brittle star Amphipholis squamata are described. Stäbchen are shown to be cuticular projections into which pass one or more uniciliate cytoplasmic processes. The proximal tips of the cilia protrude into the external environment to a variable extent. Evidence is presented for considering these ciliated endings to be the terminations of sensory neurites. Stäbchen are, in consequence, presumed to have a receptor function. Groups of stäbchen are spatially associated with fibrillar gland openings on the sides of spines while the bases of fibrillar gland cells are in contact with axons from the spine nerve which are laden with 45-270 nm diameter, electron-dense, membrane-bounded granules. The possible functional significance of these relationships is discussed in the context of a hypothesis in which fibrillar gland secretions are considered to act as food-catching mucus.

The Brittle Star digestive system is composed of buccal, pharyngeal, esophageal and stomach cavities. The buccal and pharyngeal cavities are lined by columnar cells covered by a cuticle, and are apparently concerned with mucous production. Coelomocytes and tall columnar cells are described in the esophagus and stomach epithelia. The columnar cells are adapted for nutrient absorption, enzyme synthesis, and lipid storage. Nerves are found beneath the epithelia within a connective tissue layer. Smooth muscle and coelomic layers lie external to the connective tissue layer. The coelomic layer lines a perivisceral space and has diverse modifications of its perivisceral surface; a pedicle-cuticle modification perhaps having general significance in echinoderms.

1. The arginine, creatine, and related phosphagen content was determined in muscle-containing tissues of nine species of echinoderms, from four subphyla, and in one species of hemichordate. Similar determinations were made on the unfertilized ova of the starfish, Asterias forbesi, and of the two urchins, Arbacia punctata and Lytechinus variegatus.2. Both phosphoarginine and phosphocreatine occur in moderate to large amounts in the longitudinal muscles of Thyone briareus and of Ludwigthuria floridana. Both phosphagens occur in light to moderate amounts in the rays of the starfish, Asterias forbesi, Asterias vulgaris and Echinaster sentus, with light amounts of phosphoarginine and large amounts of creatine phosphate in the rays of the starfish, Echinaster spinulosa, and of the brittle star, Ophioderma brevispina.3. Light amounts of phosphoarginine and large amounts of phosphocreatine were also found in the lantern protractors of Arbacia punctata.4. Light amounts of both phosphagens were found in total body ...

1. The brittle star Ophiactis arenosa shows uptake of C14-labelled glycine, valine, alanine and arginine from dilute solution. The process is linear with time for at least 30 minutes.2. The bulk of the radioactivity accumulated during a 30-minute exposure to glycine-C14 remains in alcohol-soluble form. Autoradiography reveals the radioactivity to be associated with glycine.3. If the animals are allowed to remain in sea water following such an exposure, there is a gradual assimilation of the label into alcohol-insoluble compounds. Some radioactivity appears as C14O2, implying oxidation of the amino acid.4. A double-reciprocal plot of concentration against rate of uptake does not give a straight line. Even at ambient concentrations as high as 10-2 M, the accumulation system apparently is not saturated.5. Common metabolic inhibitors decrease the rate of both accumulation and assimilation.6. The free amino acid pool of Ophiactis in 100% sea water is of the order of 200 mM/kg. body water. In animals subjected ...

The principal carbonate producing and environmentally significant organisms are discussed in a general manner aimed at facilitating the interpretation of certain fossil assemblages. The mode of life, effects of restriction (salinity and temperature), light, and biological breakdown of the various organisms is described in order to understand their distribution within the basin and the manner in which they contribute to the sediment mass.

The SALMFamides are a family of neuropeptides that act as muscle relaxants in echinoderms. Analysis of genome/transcriptome sequence data from the sea urchin Strongylocentrotus purpuratus (Echinoidea), the sea cucumber Apostichopus japonicus (Holothuroidea) and the starfish Patiria miniata (Asteroidea) reveals that in each species there are two types of SALMFamide precursor: an L-type precursor comprising peptides with a C-terminal LxFamide-type motif and an F-type precursor solely or largely comprising peptides with a C-terminal FxFamide-type motif. Here we have identified transcripts encoding SALMFamide precursors in the brittle star Ophionotus victoriae (Ophiuroidea) and the feather star Antedon mediterranea (Crinoidea). We have also identified SALMFamide precursors in other species belonging to each of the five echinoderm classes. As in S. purpuratus, A. japonicus and P. miniata, in O. victoriae there is one L-type precursor and one F-type precursor. However, in A. mediterranea only a single SALMFamide precursor was found, comprising two peptides with a LxFamide-type motif, one with a FxFamide-type motif, five with a FxLamide-type motif and four with a LxLamide-type motif. As crinoids are basal to the Echinozoa (Holothuroidea + Echinoidea) and Asterozoa (Asteroidea + Ophiuroidea) in echinoderm phylogeny, one model of SALMFamide precursor evolution would be that ancestrally there was a single SALMFamide gene encoding a variety of SALMFamides (as in crinoids), which duplicated in a common ancestor of the Echinozoa and Asterozoa and then specialised to encode L-type SALMFamides or F-type SALMFamides. Alternatively, a second SALMFamide precursor may remain to be discovered or may have been lost in crinoids. Further insights will be obtained if SALMFamide receptors are identified, which would provide a molecular basis for experimental analysis of the functional significance of the “cocktails” of SALMFamides that exist in echinoderms.

Background Brittle stars regenerate their whole arms post-amputation. Amphiura filiformis can now be used for molecular characterization of arm regeneration due to the availability of transcriptomic data. Previous work showed that specific developmental transcription factors known to take part in echinoderm skeletogenesis are expressed during adult arm regeneration in A. filiformis; however, the process of skeleton formation remained poorly understood. Here, we present the results of an in-depth microscopic analysis of skeletal morphogenesis during regeneration, using calcein staining, EdU labeling and in situ hybridization.

Background The evolutionary mechanisms involved in shaping complex gene regulatory networks (GRN) that encode for morphologically similar structures in distantly related animals remain elusive. In this context, echinoderm larval skeletons found in brittle stars and sea urchins provide an ideal system. Here, we characterize for the first time the development of the larval skeleton in the ophiuroid Amphiura filiformis and compare it systematically with its counterpart in sea urchin. Results We show that ophiuroids and euechinoids, that split at least 480 Million years ago (Mya), have remarkable similarities in tempo and mode of skeletal development. Despite morphological and ontological similarities, our high-resolution study of the dynamics of genetic regulatory states in A. filiformis highlights numerous differences in the architecture of their underlying GRNs. Importantly, the A.filiformispplx, the closest gene to the sea urchin double negative gate (DNG) repressor pmar1, fails to drive the skeletogenic program in sea urchin, showing important evolutionary differences in protein function. hesC, the second repressor of the DNG, is co-expressed with most of the genes that are repressed in sea urchin, indicating the absence of direct repression of tbr, ets1/2, and delta in A. filiformis. Furthermore, the absence of expression in later stages of brittle star skeleton development of key regulatory genes, such as foxb and dri, shows significantly different regulatory states. Conclusion Our data fill up an important gap in the picture of larval mesoderm in echinoderms and allows us to explore the evolutionary implications relative to the recently established phylogeny of echinoderm classes. In light of recent studies on other echinoderms, our data highlight a high evolutionary plasticity of the same nodes throughout evolution of echinoderm skeletogenesis. Finally, gene duplication, protein function diversification, and cis-regulatory element evolution all contributed to shape the regulatory program for larval skeletogenesis in different branches of echinoderms. Electronic supplementary material The online version of this article (doi:10.1186/s13227-015-0039-x) contains supplementary material, which is available to authorized users.

Evolution of echinoderm development from a feeding to a non-feeding mode can be examined by studying non-feeding larvae with structures that appear to be vestiges derived from a feeding ancestral state. The lecithotrophic larvae of the Australian brittle star Ophionereis schayeri possess such features, and the early development of this species was documented by light and scanning electron microscopy. The embryos undergo irregular cleavage, resulting in the formation of different sized blastomeres, with subsequent development through a wrinkled blastula stage. The lecithotrophic larva of O. schayeri possesses several vestigial ophiopluteal structures, including a continuous ciliated band, a larval gut, and a larval skeleton. The ciliated band is a reduced expression of the continuous ciliated band typical of ophioplutei. The larval gut is a transiently complete system, but an esophageal plug and rapid closure of the blastopore renders it nonfunctional. The larval skeleton, though reduced, consists of four rods corresponding to the body, posterolateral, anterolateral, and postoral rods characteristic of an ophiopluteus. Due to a heterochrony in larval skeletogenesis, the postoral rods develop early and simultaneously with the other rods. Compared with the larvae of other lecithotrophic ophiuroids, the larva of O. schayeri is one of the most reduced ophiopluteal forms reported to date.

Background: Marine organisms provide appreciable source of novel bioactive compounds with pharmacological potential. There is little information in correlation with anti-cancer activities of brittle star. In the present study, anti-neoplastic efficacy of Ophiocoma erinaceus methanol extract against human cervical cancer cells was investigated. Methods: The HeLa cells were cultured and exposed to brittle star methanol extract for 24 and 48 hr. The anti-proliferative properties were examined by MTT assay and the type of cell death induced was evaluated through morphological changes, flow cytometry, Annexin kit and caspase assay. To assess the anti-metastatic activity, wound healing assay was conducted and photographs were taken from the scratched areas. Further, to understand molecular mechanism of cell apoptosis, the expression of Bax was evaluated. Results: The morphological analysis and MTT assay exhibited that the brittle star methanol extract can exert dose dependent inhibitory effect on cells viability (IC50, 50 μg/ml). Flow cytometry and fluorescence microscopy demonstrated increment of sub-G1 peak, early and late apoptosis in HeLa treated cells. Wound healing migration assay showed that brittle star extract has anti-neoplastic efficacy by inhibiting cell migration. Caspase assay and RT-PCR analysis revealed that brittle star methanol extract induced caspase dependent apoptosis in HeLa cells through up-regulation of caspase-3 followed by up-regulation of Bax gene which is a hallmark of intrinsic pathway recruitment. Conclusion: These results represented further insights into the chemopreventive potential of brittle star as a valuable source of unknown therapeutic agents against human cervical cancer.

Amongst the echinoderms the class Ophiuroidea is of particular interest for its phylogenetic position, ecological importance and developmental and regenerative biology. However, compared to other echinoderms, notably echinoids (sea urchins), relatively little is known about developmental changes in gene expression in ophiuroids. To address this issue, we have generated and assembled a large RNAseq data set of four key stages of development in the brittle star Amphiura filiformis and a de novo reference transcriptome of comparable quality to that of a model echinoderm—the sea urchin Strongylocentrotus purpuratus. Furthermore, we provide access to the new data via a web interface: http://www.echinonet.eu/shiny/Amphiura_filiformis/ . We have identified highly conserved genes associated with the development of a biomineralised skeleton. We also identify important class-specific characters, including the independent duplication of the msp130 class of genes in different echinoderm classes and the unique occurrence of spicule matrix (sm) genes in echinoids. Using a new quantification pipeline for our de novo transcriptome, validated with other methodologies, we find major differences between brittle stars and sea urchins in the temporal expression of many transcription factor genes. This divergence in developmental regulatory states is more evident in early stages of development when cell specification begins, rather than when cells initiate differentiation. Our findings indicate that there has been a high degree of gene regulatory network rewiring and clade-specific gene duplication, supporting the hypothesis of a convergent evolution of larval skeleton development in echinoderms.

Background: Anti-angiogenic therapy is a crucial step in cancer treatment. The discovery of new anti-angiogenic compounds from marine organisms has become an attractive concept in anti-cancer therapy. Because little data correlated to the pro- and anti-angiogenic efficacies of Ophiuroidea, which include brittle star, the current study was designed to explore the anti-angiogenic potential of brittle star methanol extract in vitro and in vivo. Methods: The anti-proliferative effect of brittle star extract on A2780cp cells was examined by MTT assays, and transcriptional expression of VEGF and b-FGF was evaluated by RT-PCR. In an in vivo model, 40 fertilized Ross eggs were divided into control and three experimental groups. The experimental groups were incubated with brittle star extract at concentrations of 25, 50 and 100 μg/ml, and photographed by photo-stereomicroscopy. Ultimately, numbers and lengths of vessels were measured by Image J software. Data were analyzed with SPSS software (p

THE secretion of a mucus from the tube-feet of ophiuroids is well known1, although the chemical nature of this substance has not been investigated. In a study of the feeding mechanisms of ophiuroids, I find that Ophiocomina nigra (Abildgaard), a common littoral species widespread in the north-east Atlantic and Mediterranean, in addition to the mucin of the tube-feet, secretes all over the body surface an abundant mucus used in conjunction with a detritus-feeding mechanism. Attempts to find the source of this secretion have revealed two types of mucus glands previously undescribed for the species.

Pontocypria hendleri, new species, is a commensal of the ophiuroid, Ophioblenna antillensis Liitken, collected from a reef in Belize. Pontocypria calva, new species, and Pontocypria sp. B occur in trawl collections from the southwest Pacific and North Atlantic, respectively. Pontocypria helenae Maddocks, previously found on Antarctic asteroids, now has been collected apparently free-living at seven localities in the South Atlantic and South Pacific. The ostracode genus Pontocypria was established by Miiller (1894) for the freeliving, actively swimming, Mediterranean species P. spinosa, collected among calcareous algae and detritus of Posidonia. Maddocks (1968, 1979) reported three commensal species of Pontocypria: P. helenae on three species of Antarctic asteroids, P. humesi from a sponge in Madagascar, and P. sp. (hereafter called P. sp. A) on a spatangoid echinoid in the North Atlantic. The Challenger lectotype of P. meridionalis (Brady, 1880), collected near the Falkland Islands, also belongs to this genus (Maddocks, 1968). In 1985 Gordon Hendler discovered that one specimen of an ophiuroid collected in Belize was infested with an ostracode, Pontocypria hendleri, new species. Each of the ostracodes was clinging by one antennal hook to the external integument of the disk or an arm of the brittle star, in the same manner illustrated earlier for P. helenae (Maddocks, 1968, pl. 2, fig. 2). The skin of this brittle star, Ophioblenna antillensis Liitken, has abundant sieve-like spicules small enough to be ingested, but none of these spicules are visible in the gut of the ostracodes, nor is there other evidence of harm to the host. As in other species of Pontocypria, the mouthparts are weakly constructed and the gut contents unidentifiable. Maddocks (1968) suggested that these species might feed on the soft organic detritus trapped by mucus secretions of the host or even on the mucus itself. Dr. Hendler reported (letter of 9 March 1987) that "the slimy skin and other characteristics of Ophioblenna antillensis indicate that the species should be referred to the Ophiomyxidae rather than the Ophiacanthidae as heretofore presumed. Ostracods that require hosts with relatively thick, mucus-producing integument would more likely occur with ophiomyxids than with ophiuroids that have a relatively thin layer of tissue covering the skeletal plates." The deliberate nature of this association is supported by the inclusion of a young juvenile as well as adult ostracodes of both sexes. Because there is no evidence that this association is either harmful or beneficial to the host, it is here classified as commensal. Perhaps any mucus-secreting echinoderm can be infested, and we should hasten to search holothurians and crinoids to see whether they, too, harbor these ostracodes! So far, each new class of host echinoderm has yielded a different species of Pontocypria, suggesting some antiquity for this relationship. The eurybathyal, cosmopolitan distribution of this genus further indicates significant geologic age, although the weakly calcified valves are poor candidates for preservation and have not been recognized as fossils. Two additional new species of Pontocypria, either free-living or detached from their hosts, have turned up in some trawl samples and are described below.

Densities of the brittle star O. fidelis at a site on the upper continental slope (420-580 m) off eastern Tasmania, Australia, were calculated from underwater photographs. Their beds covered 61% of the substratum, with a mean density of 348 animals m-2 (52.2 g m-2). The starfish Mediaster australiensis, which was restricted to O. fidelis beds, had a mean density of 0.09 animals m-2 (5.5 g m-2). Gut analyses of trawled M. australiensis confirmed that they are predators of 0. fidelis, as were several common benthic fish species.

WHILE collecting by digging on the shore at Millbay, Salcombe, in April this year, I found three consecutive pairs of Synapta and a polynoid worm living together, and at the same time three distinct associations of the brittle star, Ophiocnida brachiata, and a small mollusc. These finds led to five later monthly visits during the best spring tides, and resulted in the observations given below.

In his monograph on the Echinoderm Fauna of South Africa H. L. Clark (I923:363) writes of Ophiocten amitinum "Several of the specimens from off the Glendower Beacon were parasitized by a nematode worm several centimeters in length, lying coiled within the disc." The record of the haul is "P. F. I3859. Glendower Beacon, N. .W., 21 miles, Ioo fms. Sh., st. 37 specimens; adult and young." The host, originally described by Lyman from material obtained by the Challenger expedition from the Kerguelen Islands and Prince Edward's Island, is reported by Clark from two other localities on the South African coast.