Myodocopid Ostracoda Research Articles

Characterisation of carapace composition in developing and adult ostracods (Skogsbergia lerneri) and its potential for biomaterials

The protective carapace of Skogsbergia lerneri, a marine ostracod, is scratch-resistant and transparent. The compositional and structural organisation of the carapace that underlies these properties is unknown. In this study, we aimed to quantify and determine the distribution of chemical elements and chitin within the carapace of adult ostracods, as well as at different stages of ostracod development, to gain insight into its composition. Elemental analyses included X-ray absorption near-edge structure, X-ray fluorescence and X-ray diffraction. Nonlinear microscopy and spectral imaging were performed to determine chitin distribution within the carapace. High levels of calcium (20.3%) and substantial levels of magnesium (1.89%) were identified throughout development. Amorphous calcium carbonate (ACC) was detected in carapaces of all developmental stages, with the polymorph, aragonite, identified in A-1 and adult carapaces. Novel chitin-derived second harmonic generation signals (430/5 nm) were detected. Quantification of relative chitin content within the developing and adult carapaces identified negligible differences in chitin content between developmental stages and adult carapaces, except for the lower chitin contribution in A-2 (66.8 ± 7.6%) compared to A-5 (85.5 ± 10%) (p = 0.03). Skogsbergia lerneri carapace calcium carbonate composition was distinct to other myodocopid ostracods. These calcium polymorphs and ACC are described in other biological transparent materials, and with the consistent chitin distribution throughout S. lerneri development, may imply a biological adaptation to preserve carapace physical properties. Realisation of S. lerneri carapace synthesis and structural organisation will enable exploitation to manufacture biomaterials and biomimetics with huge potential in industrial and military applications.

The ultrastructural development and 3D reconstruction of the transparent carapace of the ostracod Skogsbergia lerneri

The Skogsbergia lerneri is a marine ostracod which possesses a carapace that is both protective and transparent. Since development of this carapace and how it is maintained in the adult is not known, the aim of this investigation was to carry out an in-depth ultrastructural study of the ostracod carapace at different developmental stages. Standard transmission electron microscopy and novel serial block face scanning electron microscopy (SBF-SEM) were undertaken to discern carapace ultrastructure in both two and three dimensions. Analysis revealed a carapace consisting of the same basic layer structure as other myodocopid ostracods, namely an epicuticle, exocuticle, endocuticle and membranous layer, but with a thinner adult carapace of mean thickness of 19.2 ± 1.78 µm, n = 5. The carapace layers, except for instar 1 ostracods, had similar relative proportions throughout development. The endocuticle and membranous layer thickened through advancing developmental stages due to an increase in calcified crystalline polyhedrons and a greater number of chitinous lamellae in the membranous layer. Crystalline polyhedron dimensions were significantly smaller near the boundary with the membranous layer. The borders between the carapace layers were indistinct; SBF-SEM revealed an abundance of epicuticle projections into the exocuticle and apparent gradual merging at the boundary of the exocuticle and the endocuticle. Here, we discuss how the S. lerneri carapace layer structure has evolved to serve a specific mechanical function, allowing surface protection and rigidity. In addition, we suggest that the lack of pigment and graduated layer boundaries contribute to the transparency of the carapace.

Biomimetic Transparent Eye Protection Inspired by the Carapace of an Ostracod (Crustacea)

In this study we mimic the unique, transparent protective carapace (shell) of myodocopid ostracods, through which their compound eyes see, to demonstrate that the carapace ultrastructure also provides functions of strength and protection for a relatively thin structure. The bulk ultrastructure of the transparent window in the carapace of the relatively large, pelagic cypridinid (Myodocopida) Macrocypridina castanea was mimicked using the thin film deposition of dielectric materials to create a transparent, 15 bi-layer material. This biomimetic material was subjected to the natural forces withstood by the ostracod carapace in situ, including scratching by captured prey and strikes by water-borne particles. The biomimetic material was then tested in terms of its extrinsic (hardness value) and intrinsic (elastic modulus) response to indentation along with its scratch resistance. The performance of the biomimetic material was compared with that of a commonly used, anti-scratch resistant lens and polycarbonate that is typically used in the field of transparent armoury. The biomimetic material showed the best scratch resistant performance, and significantly greater hardness and elastic modulus values. The ability of biomimetic material to revert back to its original form (post loading), along with its scratch resistant qualities, offers potential for biomimetic eye protection coating that could enhance material currently in use.

Establishment of long-term ostracod epidermal culture

Primary crustacean cell culture was introduced in the 1960s, but to date limited cell lines have been established. Skogsbergia lerneri is a myodocopid ostracod, which has a body enclosed within a thin, durable, transparent bivalved carapace, through which the eye can see. The epidermal layer lines the inner surface of the carapace and is responsible for carapace synthesis. The purpose of the present study was to develop an in vitro epidermal tissue and cell culture method for S. lerneri. First, an optimal environment for the viability of this epidermal tissue was ascertained, while maintaining its cell proliferative capacity. Next, a microdissection technique to remove the epidermal layer for explant culture was established and finally, a cell dissociation method for epidermal cell culture was determined. Maintenance of sterility, cell viability and proliferation were key throughout these processes. This novel approach for viable S. lerneri epidermal tissue and cell culture augments our understanding of crustacean cell biology and the complex biosynthesis of the ostracod carapace. In addition, these techniques have great potential in the fields of biomaterial manufacture, the military and fisheries, for example, in vitro toxicity testing.

Silurian myodocopes display adaptations for a nektobenthic lifestyle: The paleobiological evidence

There is comprehensive, complementary sedimentological, faunal and paleogeographic data to indicate that myodocopid ostracods invaded the water column in the Silurian, in the latest Wenlock and especially the Ludlow Epoch, resulting in the pioneer pelagic ostracod fauna. As detailed herein, there is now also considerable paleobiological evidence, from study of rare, exceptionally preserved fossil myodocopes, particularly the nektobenthic myodocopids of the mid Wenlock Herefordshire Lagerstätte, UK, that anatomical and other features that enabled this ecological transition were already present in early Silurian myodocopes. The oldest known Silurian myodocope, a species of the Herefordshire cylindroleberidid myodocopid genus Pauline, established from shells from Telychian Llandovery Series carbonates of Greenland, would have had similar anatomical features and therefore adaptations for nektonic activity. Evidence from rare Late Ordovician species suggests even earlier nektobenthic activity by myodocopes.

Transparency in the eye region of an ostracod carapace ( Macrocypridina castanea, Myodocopida).

Many myodocopid ostracods are unusual in that they have well-developed compound eyes yet must view their environment through a shell. The cypridinid Macrocypridina castanea is relatively large among ostracods (about 5-10 mm) and is a pelagic predator. This species possess highly pigmented shells with a transparent region lying just above the eye. Here we examine the ultrastructure and transparency of this window using electron microscopy, serial-block face scanning electron microscopy and X-ray diffraction analysis and optical modelling. An internal, laminar stack was identified within the window region of the shell that formed a more regular half-wave reflector than in non-window regions, and where the distance between molecules in the chitin-protein fibrils decreases as compared to the non-window area. This results in excellent transmission properties-at around 99% transmission-for wavelengths between 350 and 630 nm due to its half-wave reflector organization. Therefore, blue light, common in the mid and deep sea, where this species inhabits, would be near-optimally transmitted as a consequence of the sub-micrometre structuring of the shell, thus optimizing the ostracod's vision. Further, pore canals were identified in the shell that may secrete substances to prevent microbial growth, and subsequently maintain transparency, on the shell surface. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology'.

Rare myodocopid ostracods from Mesozoic sections of Hungary: summary, revision and description of new taxa.

With the exception of polycopids, Mesozoic myodocopid ostracods are regarded as uncommon in the fossil record. They are known from a few localities in the Tethys, and most of them are considered to be pelagic forms. However, a relatively rich and taxonomically diverse material is derived from Hungarian sections; these represent various formations deposited during the Triassic to Cretaceous.The aim of this study is to summarize the current knowledge of Mesozoic myodocopids and to provide new information concerning their classification and phylogenetic relations. This includes new occurrences of Triassic entomozoid Schallreuterizoe groosae Kozur, 2004, cylindroleberidid Triadocypris sp., cypridinid Palaeocypridina tulceaensis Sebe, 2013, Jurassic thaumatocyprid Pokornyopsis cf. bettenstaedti (Bartenstein, 1949) and P. feifeli (Triebel, 1941). The revision of the holotype of gigantic Triassic Triadogigantocypris balatonica Monostori, 1991 give new results concerning the valve structure and taxonomic position of the genus. Two new genera (Neorichterina n. gen. and Hungaroleberis n. gen.) and four new species (Neorichterina striata n. sp., Pokornyopsis csurgokutensis n. sp., Hungaroleberis retiferus n. sp. and Palaeocypridina goeroegae n. sp.) of the subclass Myodocopa are described. Moreover, most of the Albian to Cenomanian representatives of "Conchoecia" are newly classified as Entomozoidae (Neorichterina n. gen.), which allows to extend the range of the family up to the Cretaceous. A summary of the relevant assemblages present in Hungary will help to complement the existing, previously published literature on myodocopids, and also clarify details about the phylogenetic model of the group.

A guide to the morphology of bioluminescent signaling Cypridinid Ostracods from the Caribbean Sea, and a tabular key to the genera

This guide is a convenient graphic description of all the salient features of the bioluminescent ostracods in the family Cypridinidae from the Caribbean Sea that are useful, and essential, for their accurate identification upon microscopic examination of dissected specimens. Over 70 species of courtship-signaling ostracods [with 22 of these formally described] have been discovered in the Caribbean, but nowhere else, and many more await discovery. The guide is also helpful for providing comparative information on the morphology of all myodocopid ostracods in the family Cypridinidae from around the globe. We also include a tabular key to males of the six known genera (3 described) of signaling cypridinid ostracods and one commonly collected non-luminescent congener.

Benthic myodocopid Ostracoda (Philomedidae) from the Southern Ocean.

This study is based on the material of myodocopid ostracodes of the family Philomedidae collected by the Russian Antarctic Polar Expeditions (1963-2007) and the Germany Expeditions on R/V "Polarstern" (1990-2002) from the continental shelf and upper slope near the Mawson and Davis stations, the Weddell Seas, the region of the South Shetland Islands near the Russian Polar station "Molodezhnaya" and adjacent waters. Eight philomedid species belonging to two genera were identified in these collections. Scleroconcha tuberculata sp. nov. is described and figured as a new species. Additional descriptions and figures for the species S. gallardoi Kornicker, 1971, Philomedes assimilis Brady, 1907, P. charcoti Daday, 1908, P. heptatrix Kornicker, 1975, P. rotunda Skogsberg, 1920, P. orbicularis Brady, 1907 and P. tetrathrix Kornicker, 1975 are given. Keys for all species of the mentioned genera known from the Southern Ocean are presented. A list of sampling stations and species collected is provided in the Appendix 1.

A pelagic myodocopid ostracod from the Silurian of Arctic Russia

Abstract. The Silurian myodocope ostracod Richteria migrans is reported from Arctic Russia, from Kotel’ny Island (New Siberian Islands) and the Taimyr Peninsula in strata of Ludfordian (late Ludlow, Late Silurian) age. These occurrences extend the biogeographical range of R. migrans from tropical to mid latitudes of the Early Palaeozoic Rheic Ocean in the palaeo-Southern Hemisphere, into subtropical regions of the palaeo-Northern Hemisphere on, or adjacent to, the Siberia Palaeocontinent. The new records reinforce the idea that R. migrans had wide dispersal capacity and probably possessed a pelagic lifestyle. It also endorses the use of R. migrans as a biostratigraphical marker fossil for the Ludfordian Stage, Ludlow Series, Upper Silurian.

The early Ludfordianleintwardinensisgraptolite Event and the Gorstian-Ludfordian boundary in Bohemia (Silurian, Czech Republic)

The late Gorstian to early Ludfordian hemipela- gic succession of the south-eastern part of the Prague Syn- form preserves a rich fossil record dominated by 28 species of planktic graptoloids associated with pelagic myodocopid ostracods, pelagic and nektobenthic orthocerid cephalopods, epibyssate bivalves, nektonic phyllocarids, rare dendroid graptolites, brachiopods, crinoids, trilobites, sponges and macroalgae. Faunal dynamics have been studied with parti- cular reference to graptolites. The early Ludfordian leintwar- dinensis graptolite extinction Event manifests itself as a stepwise turnover of a moderate diversity graptolite fauna rather than an abrupt destruction of a flourishing biota. The simultaneous extinction of the spinose saetograptids Saeto- graptus clavulus, Saetograptus leintwardinensis and the rare S. sp. B. at the top of the S. leintwardinensis Zone was preceded by a short-term acme of S. clavulus. Cucullograptus cf. aver- sus and C. rostratus vanished from the fossil record in the lower part of the Bohemograptus tenuis Biozone. No mass proliferation of Bohemograptus has been observed in the postextinction interval. Limited indigenous speciation gave rise to Pseudomonoclimacis kosoviensis and Pseudomonoclima- cis cf. dalejensis. Egregiograptus (the only novel element of cryptic origin) made its earliest occurrence in association with the latest cucullograptids. A postextinction graptolite assemblage of moderate diversity, composed for the most part of long-ranging taxa, persisted through the middle and upper tenuis Biozone until new rediversification in the Neo- cucullograptus inexpectatus Biozone. Unlike the graptoloids, the planktic, epiplanktic, nektonic and nektobenthic shelly fauna did not suffer significant extinction in the early Lud- fordian. The Gorstian-Ludfordian boundary is placed at the lowest occurrence of S. leintwardinensis in spite of the very modest graptolite record available from the Ludfordian GSSP where no graptolites occur below the basal bed of the Lower Leintwardine Formation. Elsewhere, the Gorstian-Ludfordian boundary has been placed at the base of the Saetograptus linearis Biozone which has been considered roughly correla- tive with the leintwardinensis Biozone. Indeed, our morpho- metric study places the worldwide biozonal index species S. linearis in synonymy with S. leintwardinensis and thus considerably enhances the biostratigraphical utility of the lat- ter index species. Pseudomonoclimacis antiqua sp. nov. is described.

The North American ostracod Eusarsiella zostericola (Cushman, 1906) arrives in mainland Europe

In sediment samples collected in the Oosterschelde, a marine embayment in the southwest of The Netherlands (southern North Sea), nine specimens of a non-native myodocopid ostracod were found. The ostracods were identifed as the North American species Eusarsiella zostericola (Cushman, 1906), previously introduced to southeastern England, probably with imported American oysters.

Hydrothermal vent myodocopid ostracods from the Eifelian (Middle Devonian) of southern Morocco

A monospecific assemblage of myodocopid ostracods has been found in the Middle Devonian of a unique hydrothermal vent system of Hamar Laghdad (eastern Anti-Atlas, southern Morocco), which developed over a submarine eruption of basaltic rocks. This fauna has been recovered from a neptunian dyke representing the sediment infill of an Eifelian venting fissure discovered in the central part of Hamar Laghdad. The assemblage consists of thousands of relatively large shells forming a coquina layer in which the valves are disarticulated, perfectly washed, well sorted and stacked into each other. Their orientation points to transport due to fluids migrating in the vent system. The ostracod specimens, on the base of the general outline, the presence of rostrum and rostral incisure is assigned to the order Myodocopida. The new genus and species Hamaroconcha kornickeri is proposed, most likely representing a new family. Its carapace morphology gives no clear clue to its mode of life; however, a relatively long rostral incisure may suggest that frontal appendages of this species were sufficient for active swimming. Therefore, a nectobenthic lifestyle is postulated for H. kornickeri nov. gen., nov. sp. Isotope data from the sediment infill provide evidence for the activity of hydrothermal fluids.

An exceptionally preserved myodocopid ostracod from the Silurian of Herefordshire, UK

An exceptionally preserved new ostracod crustacean from the Silurian of Herefordshire, UK, represents only the third fully documented Palaeozoic ostracod with soft-part preservation. Appendages, gills, gut system, lateral compound eyes and even a medial eye with a Bellonci organ are preserved, allowing assignment of the fossil to a new genus and species of cylindroleberidid myodocope (Myodocopida, Cylindroleberididae). The Bellonci organ is recorded for the first time in fossil ostracods. The find also represents a rare occurrence of gills in fossil ostracods and confirms the earliest direct evidence of a respiratory-cum-circulatory system in the group. The species demonstrates remarkably conserved morphology within myodocopes over a period of 425 Myr. Its shell morphology more closely resembles several families of myodocopes other than the Cylindroleberididae, especially the Cypridinidae and Sarsiellidae, thus questioning the utility of the carapace alone in establishing the affinity of fossil ostracods.

Ostracoda of Moss Town Blue Hole, Great Exuma Island, Great Bahama Bank (Crustacea: Ostracoda: Myodocopa)

Eight species of myodocopid Ostracoda (six Myodocopina, one Halocypridina, and one Cladocopina) are reported from 30 to 60 m depths in Moss Town Blue Hole, an ocean blue hole located in a bay on the west side of Great Exuma Island, Exuma Cays, Great Bahama Bank. The collection from Moss Town Blue Hole contained no new species, but five species had not been reported previously from the blue holes of Great Exuma Island, and three species had not been reported previously from the blue holes of the Exuma Cays. The collection provided the opportunity to describe the adult male and female, as well as early instars, of Eusarsiella fax and Metapolycope duplex, and the adult female of Eusarsiella merx, and also, to compare the ostracode populations in the various niches in the Exumas.

Complex sexual courtship displays by luminescent male marine ostracods

In the western Caribbean Sea, about an hour after the sun sets, a complex and ritualized light show of precise, vertically placed luminescent pulses erupts over shallow grassbeds. These are among the most complex displays known in marine systems. Displays consist of repeated trains of secreted bioluminescent pulses in a specific pattern ejected into the water column as courtship signals by male Vargula annecohenae, which are small (<2 mm) myodocopid ostracod crustaceans. Although these animals display in near darkness, we have used image intensification and infrared videography and three-dimensional analysis in the lab to demonstrate that each luminescent display train, which can be up to 60 cm long, consists of two distinct luminescent and swimming phases. The first, or 'stationary,' phase consists of three (usually) bright, longer pulses placed close together, with the male swimming in a looping pattern. We hypothesize that this pattern acts as an attention-grabbing signal for receptive females. The stationary phase is followed by the 'helical phase,' which consists of about a dozen evenly placed dimmer, shorter pulses secreted by an individual male rapidly spiraling upward in a helical pattern. We hypothesize that this phase, which has very uniform interpulse intervals and distances, helps an approaching female target and intercept the rapidly moving male. Here we provide details of these two phases, and produce a three-dimensional model of a multiply-displaying male.

Ostracoda (Myodocopa) from Anchialine Caves and Ocean Blue Holes

Eleven stygobitic myodocopid ostracodes (two new–Danielopolina palmeri and Spelaeoecia hox) in the Order Halocyprida are reported from anchialine waters in 11 inland blue holes in Bahamas. One stygobitic halocyprid ostracode is reported from two localities in Bermuda, and one from a cave in Mexico. A new subfamily, Spelaeoeciinae, is proposed to contain the genus Spelaeoecia, and the subfamily Deeveyinae is elevated to family status. Two new species of cladocopid ostracode (Pseudopolycope helix and Pontopolycope storthynx), are described from a cave in Mexico and an oceanic blue hole in the Bahamas. Nine species of myodocopid ostracodes (four new—Rutiderma flex, Eusarsiella syrinx, Eusarsiella fax, and Synasterope matrix) in the Suborder Myodocopina and one species in the Suborder Halocypridina are reported from ocean blue holes in the Bahamas. This is the first report of a halocyprid living in both an inland and ocean blue hole in the Bahamas. The sarsiellid genus Dantya Kornicker &amp; Cohen 1978 is reported for the first time in the Bahamas, but the single juvenile specimen is left in open nomenclature as Dantya sp. A. The development of Deeveya bransoni and Eusarsiella syrinx is described in detail. With the exception of one species of Danielopolina from deep waters of the South Atlantic, all other species of Danielopolina, Spelaeoecia and Deeveya have been previously found only in inland, anchialine caves. The discovery of Deeveya inhabiting deeper, hydrologically-isolated waters in ocean blue holes, which are otherwise comparable to classical anchialine environments, has raised questions concerning the geographic limits to the anchialine habitat and its supposed reliance on terrestrial inputs.

Embryonic development clarifies polyphyly in ostracod crustaceans

AbstractThe present study describes the embryonic developmental process of the bioluminescent ostracod crustacean Vargula hilgendorfii. Optical microscopy, scanning electron microscopy, DAPI staining and video recording were used for observations. This study is the first detailed report of the embryonic development of a myodocopid ostracod. Contrary to previous studies, cleavage occurred in the yolk sphere and no evident cleavage furrow was found. No nauplius stage was found, and five pairs of appendages developed simultaneously. A bivalved carapace developed from two independent buds of the carapace valves. The buds of the left and right valves are enlarged, and become combined. The combined ‘one‐piece’ carapace was divided by the formation of a hinge, and the usual bivalved carapace was formed. On the 16th day, embryos hatched as juveniles with six pairs of appendages, a pair of immature appendages, a pair of compound eyes, a median eye and a bivalved carapace. An important suggestion for the classification of Ostracoda is derived from the observed development of appendages and carapace, because the subclass Ostracoda is defined mainly by the similarities of appendages and the bivalved carapace. The present observations clearly show that the developmental process of Myodocopa differs from that of Podocopa, and supports polyphyly of the Ostracoda.

サイズヒストグラムによるウミホタル個体群動態の解析

The life history of the myodocopid ostracod Vargula hilgendorfii was investigated by size-frequency distribution analysis in Akita Port, Japan, from April to December, 2003. Vargula hilgendorfii individuals were collected using baited traps, and the carapace length was measured by computer analysis of a digital photograph of each individual taken under a stereomicroscope. The population was divided into seven groups based on carapace length. These groups corresponded to the five juvenile stages, the adult male stage, and the adult female stage. Each peak in the number of V. hilgendorfii individuals is related to the growth of the population. Our field data clearly suggest that the Akita Port population of V. hilgendorfii produces two generations per year. Adults that survived the winter became sexually active in May and released free-living juveniles in July. After reproducting, they died without having entered a second reproductive cycle. The first-generation juveniles reached the adult stage after five molts and released second-generation juveniles in September. By winter, these second-generation juveniles reached maturity without releasing any new juveniles; they become sexually active in the following spring.

The evolutionary pathway of light emission in myodocopid Ostracoda

The evolutionary history of bioluminescence and iridescence in myodocopid ostracods was estimated by phylogenetic analysis of mitochondrial 16S ribosomal RNA sequences. The inferred phylogeny of the myodocopids suggests that the common ancestor of Myodocopida evaluated in this study exhibits iridescence. This type of light emission was once lost and recaptured independently in the descendant lineages. Bioluminescent species also evolved from non-luminous ancestral species. In the suborder Myodocopina, all the bioluminescent species form a monophyletic group, suggesting that bioluminescence evolved only once. Structural differences between two bioluminescent groups in the order Myodocopida suggests independent origins for bioluminescence. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 449–455.