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A new ichnospecies of Cardioichnus, Cardioichnus biloba isp. nov., is described and documented from shallow marine strata of Cretaceous (Late Albian) age in southern New Mexico, USA. It is a heart-shaped resting trace which, unlike all other ichnospecies of Cardioichnus, is epichnial and increases in width to a bilobate trace, often with a raised anterior terminus. Only the posterior end of this trace is associated with Bichordites burrows, and the anterior end is bilobate and undisturbed. This represents a resting position which differs from other known species of this cubichnium, which are hypichnial and subquadrate in symmetry. The tracemaker is a spatangoid echinoid, most likely Heteraster d'Orbigny, 1853. [ABSTRACT FROM AUTHOR]

The associations between Cephalotrichella echinicola Chernyshev et al., 2019, and the heart urchin Metallia spp. described here represent the first report on the symbiotic relationship between palaeonemerteans and echinoderms. In addition, it is the first report of a symbiotic relationship between nemerteans and heart urchins, and the third known association between nemerteans and echinoderms. Numerous specimens of C. echinicola were found associated with heart urchins Metallia spatagus and M. sternalis in four localities of the Bay of Nhatrang, Vietnam, South China Sea, at 6–10 m water depth buried in the coarse sand to a sediment depth of 10–20 cm. The infestation prevalence and mean intensity were higher in M. spatagus, than in M. sternalis, 77% and 68%, and 10 and 3 nemertean individuals per heart urchin host, respectively. Each infested host harbored from 1 to 49 nemertean individuals, and multiple infestations with three or more individuals per host were very common. Based on the high level of prevalence, absence of the nemertean on the other sand-dwelling heart urchins in the area, the complete absence of the nemerteans in the sandy bottom of the bay and in the sediment surrounded infested host individuals, and no reaction by the host to the nemertean's movement on the host's surface we consider this a symbiotic association. [ABSTRACT FROM AUTHOR]

Abstract Prospatangus thieryi Lambert, 1909 (Echinoidea, Spatangoida) is an echinoid from the Early Miocene of Sardinia, Italy. The original description, mainly based on subjective morphological observations (e.g. from Lambert, 1909: "une forme un peu plus longue que large, à sillon peu profond, apex légèrement excentrique en avant"), made it problematic the comparison with other similar taxa. New observations based on a large set of structural and morphometric data taken from the lectotype and a newly collected specimen, both from Cameseda (Ales, Oristano Province, Sardinia, Italy), one of the two localities indicated by Lambert (1909) in the type area, enabled to improve the definition of this species and to transfer it into a new genus, Sardospatangus nov. gen. It differs from Spatangus Gray, 1825 (junior synonym: Prospatangus Lambert, 1902) mainly by the labrum, which is more elongate and in contact with two plates on either side of the adjacent ambulacra (I and V) instead of one, and by a lower total number of plates in the ambulacrum III. Two additional species of Sardospatangus nov. gen are identified within a large number of specimens from the Miocene of Sardinia examined in public institutions: S. caschilii nov. sp., proposed as the type species of the new genus, and S. arburensis nov. sp. [ABSTRACT FROM AUTHOR]

Abstract Rhynobrissus cuneus, a small, irregular sea urchin, was originally described from 5 tests washed onto the beach at Fort Macon, NC, and it has been reported only once since, from 7 specimens collected from Playa Jicacal, Los Tuxtlas, Veracruz, Mexico. Here we record R. cuneus from Buxton Beach, Dare County, NC, ∼124 km (77 mi) directly northeast of the 1957 record. This is only the third report of R. cuneus and represents the northernmost record of the species. Specimens were found as empty tests washed ashore, most likely a result of recent beach-restoration activities. [ABSTRACT FROM AUTHOR]

Neogene Argentinean echinoids are important biostratigraphic tools. New specimens of Schizaster iheringi (de Loriol, 1902) from Early Miocene sedimentites (Chenque Formation, Patagonia, Argentina) allowed us to improve its original description, providing for the first time details of the apical disc and the oral side of test. The species is included into the genus Brisaster: the first unquestionable documented reference to the taxon from the Neogene of Argentina. All previously reported specimens of this species are evaluated, concluding that the stratigraphic range of the genus Brisaster in Patagonia must be restricted to the Early Miocene. [ABSTRACT FROM AUTHOR]

Preliminary analyses revealed the presence of at least five mitochondrial clades within the widespread sea urchin Echinocardium cordatum (Spatangoida). In this study, we analyzed the genetic (two mitochondrial and two nuclear sequence loci) and morphological characteristics (20 indices) from worldwide samples of this taxon to establish the species limits, morphological diversity and differentiation. Co-occurring spatangoid species were also analyzed with mitochondrial DNA. The nuclear sequences confirm that mitochondrial lineages correspond to true genetic entities and reveal that two clades (named A and B1) hybridize in their sympatry area, although a more closely related pair of clades (B1 and B2), whose distributions widely overlap, does not display hybridization. The morphology of all E. cordatum clade pairs was significantly differentiated, but no morphological diagnostic character was evidenced. By contrast, other spatangoid species pairs that diverged more recently than the E. cordatum clades display clear diagnostic characters. Morphological diversity thus appears responsible for the absence of diagnostic characters, ruling out stabilizing selection, a classical explanation for cryptic species. Alternative classical explanations are (i) environmental plasticity or (ii) a high diversity of genes determining morphology, maintained by varying environmental conditions. We suggest a new hypothesis that the observed morphological diversity is selectively neutral and reflects high effective population sizes in the E. cordatum complex. It is supported by the higher abundance of this taxon compared with other taxa, a trend for the genetic and morphological diversity to be correlated in Europe, and the higher genetic and morphological diversities found in clades of E cordatum (except B1) than in other spatangoid samples in Europe. However, the Pacific clades do not confirm these trends. [ABSTRACT FROM AUTHOR]

Spines of irregular echinoids occur in very high abundance in each specimen, and display distinct architecture as a result of the specialized functions of the spines; however, studies on spine microstructure in atelostomate echinoids have rarely been carried out. Accordingly, little is known about their specific morphology. This work aims to elaborate differences in the spine morphology of selected Atelostomata (Spatangoida and Holasteroida) in detail, and to discuss spine microstructure for its potential systematic value. Based on 82 atelostomate species (56 spatangoids and 26 holasteroids), we show that the perforation pattern in the internal cylinder of the spine (helicoidal versus horizontal pattern) provides a safe distinction between the Spatangoida and Holasteroida. According to this character we discuss the geological history of atelostomate echinoids, in particular their migration into the deep sea, based on well-preserved records of fossil spines. © 2015 The Linnean Society of London [ABSTRACT FROM AUTHOR]

The microstructure of many echinoid species has long fascinated scientists because of its high porosity and outstanding mechanical properties. We have used X-ray microtomography to examine the test of Echinocardium cordatum (heart urchin), a burrowing cousin of the more commonly known sea urchins. Three dimensional imaging demonstrates that the bulk of the test is composed of only two distinct, highly porous, fenestrated regions (stereom), in which the thickness of the struts is constant. Different degrees of porosity are achieved by varying the spacing of the struts. Drawing an analogy to vertebrate trabecular bone, where for example, human bone has a connectivity density of ≈1/mm 3 , we measure up to 150,000 strut connections per mm 3 . Simulations of mechanical loading using finite element calculations indicate that the test performs at very close to the optimum expected for foams, highlighting the functional link between structure and mechanical properties. [ABSTRACT FROM AUTHOR]

The molecular mechanism of the larval mesenchyme cell specification in echinoids has been well analyzed. However, most of the data have been provided by studies of a single group of echinoids, the order Camarodonta. Little is known about this mechanism in other echinoid orders. We examined the expression patterns of mesenchyme specification genes, micro1 , hesC , alx1 , tbr , ets1 , cyp1 , and gcm , in the two non-Camarodonta echinoids, Glyptocidaris crenularis and Echinocardium cordatum . We found that the expression patterns of some genes contained characteristics that were unique to one of the species; others were shared by the two species. Some of the shared characteristics of G. crenularis and E. cordatum are not found in the species belonging to Camarodonta, suggesting the derived status of this order. The expression of ets1 in E. cordatum aboral ectoderm is one of the molecular level modifications possibly related to an evolutionarily novel larval structure, the posterior process. Our results suggest that a considerable number of modifications in the mesenchyme specification mechanisms have been introduced during the echinoid evolution. [ABSTRACT FROM AUTHOR]

Three mass accumulations of sea urchins from the Miocene of Sardinia show a number of taphonomic features which set them apart from previously described echinoid assemblages from the Cenozoic in which they represent: (1) monotypic assemblages; (2) include very well-preserved remains of either regular or spatangoid echinoids; and (3) originate in deeper water environments. These accumulations are compared using a detailed sedimentological and taphonomic analysis including preservational fabrics, taphonomic signatures, size frequency distributions, density of occurrences and preferred orientations. The possible role of gregarious behaviour contributing to mass occurrences and the specific sedimentary events leading to the excellent preservation are discussed. The interpreted depositional environment of all three deposits is that of a storm-dominated, siliciclastic shelf environment. A phymosomatid assemblage represents rapid burial through obrution of a highly dense, freshly dead community. A Brissopsis-dominated spatangoid assemblage represents a mixed accumulation of parautochthonous and transported skeletons. The third assemblage consisting of regular echinoid spines and rare tests represents a composite tempestite. Differences in the depositional environments are related to their position along onshore-offshore gradient with the first two beds originated in a deeper setting than that of the spine accumulation. This study shows that the preservation of assemblages containing complete regular echinoids and spatangoids is higher in deeper water settings than in shallow water environments. [ABSTRACT FROM AUTHOR]

A thorough understanding of the sea urchin (Echinodermata: Echinoidea) digestive tract anatomy is a prerequisite for the correct interpretation of physiological and biomechanical analyses focusing on the gut architecture of this ecologically important group of marine invertebrates. A number of studies have addressed the general arrangement of the sea urchin digestive tract, but accessory structures such as siphons and caeca have received less attention. Two studies carried out to analyze the gut physiology of various marine invertebrates briefly mentioned the presence of a previously undescribed pouch in the posterior digestive tract of the heart urchin (Echinoidea: Spatangoida) species Brisaster latifrons. Dissections, histological, and magnetic resonance imaging data, as well as three-dimensional reconstructions corroborate these findings. The novel structure-here termed the intestinal caecum-is suspended by a thin mesentery within a coil formed by the posteriormost part of the intestine. The kidney-shaped organ constitutes a derivative of the intestine, to which it is laterally connected through a narrow canal. In contrast to the sediment-packed main digestive tract, the intestinal caecum is filled with liquid and a flocculent mass. The organ's histology is characterized by a thin connective tissue layer with only a small number of hemal lacunae and muscle fibers, as well as an inner simple columnar epithelium that contains numerous dark-brown vacuoles. The intestinal caecum is found exclusively among members of the Schizasteridae (Spatangoida: Paleopneustina). Specifically, the organ is present in selected species of the genera Abatus, Brisaster, and Tripylaster, but not in the other seven schizasterid genera analyzed. The intestinal caecum is not homologous to the sometimes equally named accessory structure present in the posterior digestive tract of other spatangoid taxa such as Echinocardium or Heterobrissus. Consequently, the previously introduced term recto-intestinal caecum is here applied for this latter organ. No correlation could be found between the absence or presence of the intestinal caecum and any known biological or morphological characteristics of schizasterid heart urchins. The distribution of the organ among schizasterids supports a close relationship of the genera Brisaster, Tripylaster, and selected species of Abatus. [ABSTRACT FROM AUTHOR]

Abstract: The paper describes the spatangoid echinoids belonging to Macraster, which could be found in the Albian deposits (Kazhdumi Formation) at the Anneh anticline situated in Zagros Mountains, Southwest of Iran. The aim is to re-examine, and redefine three species: M. douvillei, M. longesulcatus and M. obtritus. Douvillaster and Macraster genera are synonymized and then the assignment of nominal Tethyan species belonging to the same genera is reviewed. The substantial reduction of species does not strongly impact the biodiversity patterns. Neither the bio-geographical provinciality nor the temporal trends of taxonomic richness are affected. Among the Cretaceous spatangoids, Macraster is a highly specialized taxon that displays outstanding adaptations of the ambulacra to improve in the gaseous exchanges. This, in return, triggers the higher frequency of the taxon in the warm shallow waters of the Tethyan margins, and in oxygen-depleted environments. [Copyright &y& Elsevier]

A galeommatid bivalve mollusk, representing a new species, is described from off the coasts of California and Vancouver Island, British Columbia. The new bivalve has a commensal relationship with the heart urchin, Brisaster latifrons. It has been observed crawling between the oral spines of this urchin, frequently near the peristome. The bivalve has been recorded from 80 (Vancouver Island) to 444 (southern California) meters depth, in muddy sediments. In common with other galeommatoideans, the new species broods its young; however it differs from the large majority of commensal members in lacking planktotrophic larval development. Waldo arthuri, new species, has multiple morphological, ecological and developmental similarities to other members of the genus Waldo Nicol, 1966, from the southern Atlantic and Antarctic Oceans. This is most pronounced for the Argentine species, Waldo paucitentaculatus Zelaya & Ituarte, 2013, W. arthuri's sister species in nuclear and mitochondrial gene trees. Despite this close relationship, W. arthuri is phylogentically distinct and possesses several hinge, shell sculpture, foot, and mantle tentacle characteristics that merit its description as new. [ABSTRACT FROM AUTHOR]

Habitats are often defined by the presence of key species and biogenic features. However, the ecological consequences of interactions among distinct habitat-forming species in transition zones where their habitats overlap remain poorly understood. We investigated transition zone interactions by conducting experiments at three locations in Mahurangi Harbour, New Zealand, where the abundance of two habitat-forming marine species naturally varied. The two key species differed in form and function: One was a sessile suspension-feeding bivalve that protruded from the sediment (Atrina zelandica; Pinnidae); the other was a mobile infaunal urchin that bioturbated sediment (Echinocardium cordatum; Spatangoida). The experimental treatments established at each site reflected the natural densities of the species across sites (Atrina only, Echinocardium only, Atrina and Echinocardium together, and plots with neither species present). We identified the individual and combined effects of the two key species on sediment characteristics and co-occurring macrofauna. After five months, we documented significant treatment effects, including the highest abundance of co-occurring macrofauna in the Atrina-only treatments. However, the facilitation of macrofauna by Atrina (relative to removal treatments) was entirely negated in the presence of Echinocardiuns at densities >10 individuals/m2. The transitional areas in Mahursngi Harbour composed of co- occurring Airina and Echinocardiuns are currently widespread and are probably more common now than monospecific patches of either individual species, due to the thinning of dense Atrina patches into sparser mixed zones during the last 10-15 years. Thus, although some ecologists avoid ecotones and habitat edges when designing experiments, suspecting that it will skew the extrapolation of results, this study increased our understanding of benthic community dynamics across larger proportions of the seascape and provided insights into temporal changes in community structure associated with patch dynamics. Particularly in situations where non-abrupt habitat transitions are commonplace, documentation of community dynamics in individual biogenic habitats and in mixed transition zones is required in order to scale-up and generalize results. [ABSTRACT FROM AUTHOR]

A new genus and species of spatangoid echinoid, Tripatagus pittsi n. gen., n. sp., is described from the Marianna Limestone, Lower Oligocene (Rupelian) of Mississippi. The family is uncertain: plating of the plastron suggests the family Maretiidae; ethmolytic apical system, presence of both peripetalous and subanal fascioles, and depressed petals suggest the family Brissidae or Macropneustidae. It differs from nearly all other genera of these families in the character of 3 gonopores in an ethmolytic apical system, lacking a gonopore in genital plate 2. [ABSTRACT FROM AUTHOR]

Abstract: As part of a broader study on benthic–pelagic coupling in the southern North Sea, specimens of the common heart urchin Echinocardium cordatum were sampled for analyses on phytopigments and fatty acids in their guts. Results were interpreted in the context of feeding and ecological functioning of the heart urchins in the benthic system. Ingestion selection factors for both component groups were relatively high, 5 to 9 for chlorophyll a and 9 to 130 for total fatty acids. The data point to at least partially different sources of the pigments and of the fatty acids. Next to algal detritus, small infauna relatively rich in fatty acids might be preferentially co-ingested with the detritus. Due to digestive breakdown and absorption, the concentrations of pigments and fatty acids were importantly decreased, indicating a rather high digestion efficiency for this subsurface deposit feeder, up to 80%. The results indicate that E. cordatum increases its energy acquisition by strong selectivity and a high digestive efficiency. Optimal foraging is likely to apply on deposit-feeding invertebrates in relatively food-rich coastal environments as much as it does in the food-poor deep-sea environment. Using chlorophyll a as a proxy for carbon, the contribution of the urchin population to the momentary benthic carbon budget was calculated at 7% to 42%. [Copyright &y& Elsevier]

Abstract: Echinocardium cordatum had long been considered as cosmopolitan, but molecular data revealed it is a complex of cryptic species, with two non-hybridizing species (B1 & B2) in the Mediterranean Sea living in syntopy with Echinocardium mediterraneum. Histological analyses of the gonads from a 17-month sampling period revealed a statistically significant time lag between the Maturity Indices of E. cordatum and E. mediterraneum. The main environmental stimulus may be different for the two nominal species, possibly seawater temperature for E. cordatum and chlorophyll a concentration for E. mediterraneum. Within the E. cordatum complex, spawning timing and synchrony are different according to major geographic areas (Atlantic/Pacific/Mediterranean) and/or the corresponding genetic subdivision [A/P/(B1 & B2)]. In contrast, the effects of temperature on the reproductive cycle seem rather to mirror the genetic lineages than environmental similarities of the different localities. Between the sister species (B1 & B2) no differences could be detected, maybe due to small sample sizes. [ABSTRACT FROM AUTHOR]

The article presents a study on multiple shifts from planktotrophic to non-planktotrophic larval development in spatangoid sea urchins during the Late Cretaceous period. Five clades of non-planktotrophic taxa were identified using genus-level phylogeny. The authors suggest that the shifts to non-planktotrophic development are clustered in particular episodes of geological history. They explain the possible role of predation and environmental change in such shifts in developmental strategy.

Theoretically, disturbance and diversity can influence the success of invasive colonists if (1) resource limitation is a prime determinant of invasion success and (2) disturbance and diversity affect the availability of required resources. However, resource limitation is not of overriding importance in all systems, as exemplified by marine soft sediments, one of Earth's most widespread habitat types. Here, we tested the disturbance-invasion hypothesis in a marine soft-sediment system by altering rates of biogenic disturbance and tracking the natural colonization of plots by invasive species. Levels of sediment disturbance were controlled by manipulating densities of burrowing spatangoid urchins, the dominant biogenic sediment mixers in the system. Colonization success by two invasive species (a gobiid fish and a semelid bivalve) was greatest in plots with sediment disturbance rates <500 cm³·m-2·d-1, at the low end of the experimental disturbance gradient (0 to >9000 cm³·m-2·d-1). Invasive colonization declined with increasing levels of sediment disturbance, counter to the disturbance-invasion hypothesis. Increased sediment disturbance by the urchins also reduced the richness and diversity of native macrofauna (particularly small, sedentary, surface feeders), though there was no evidence of increased availability of resources with increased disturbance that would have facilitated invasive colonization: sediment food resources (chlorophyll a and organic matter content) did not increase, and space and access to overlying water were not limited (low invertebrate abundance). Thus, our study revealed the importance of biogenic disturbance in promoting invasion resistance in a marine soft-sediment community, providing further evidence of the valuable role of bioturbation in soft-sediment systems (bioturbation also affects carbon processing, nutrient recycling, oxygen dynamics, benthic community structure, and so on.). Bioturbation rates are influenced by the presence and abundance of large burrowing species (like spatangoid urchins). Therefore; mass mortalities of large bioturbators could inflate invasion risk and alter other aspects of ecosystem performance in marine soft-sediment habitats. [ABSTRACT FROM AUTHOR]

Five species of deep-sea pourtalesiid echinoids were collected by the RV G.O. Sars MAR-ECO expedition to the northern part of the Mid-Atlantic Ridge: Solenocystis imitans new genus, new species, Echinosigra phiale (Thomson, 1872), Echinosigra (Echinogutta) fabrefacta Mironov, 1974, and two unidentified species of Pourtalesia. Three types of plastron plating are distinguished within the family Pourtalesiidae; in Solenocystis new genus the plating is similar to that in Spatagocystis, a genus known only from the deep-sea Antarctic. Each of three groups with distinctive plastron plating shows a continuous morphological gradation from a less elongated test without subanal rostrum to an extraordinarily elongated test with large rostrum and wide subanal fasciole; the ratio width/length of test varies from 0.86 to 0.12. Some morphological characters of the pourtalesiids are regarded as adaptations to burrowing and appear to be correlated with test elongation. The family is represented in the northern Atlantic only by 'advanced' genera (Echinosigra, Pourtalesia and Solenocystis) with very elongated tests. [ABSTRACT FROM AUTHOR]

Abstract  The prejuvenile development of Echinocardium cordatum (Echinoidea) was investigated by means of scanning electron, confocal and light microscopes, aiming to illustrate the early life history of a spatangoid representative and to compare it with the other major echinoid groups. During the larval development of E. cordatum, two periods follow one another. The first one takes 12 days; it ends with the formation of a complete echinopluteus with twelve elongated larval arms. The second lasts from 3 to 12 days; it is entirely devoted to the building of the echinid rudiment and ends with the acquisition of larval competence. No appendage other than arms develops at the larva’s outer surface. Competent larvae are demersal. They settle onto the substratum and test it for suitability using the five rudiment podia that protrude through the vestibule opening. Metamorphosis is a rapid event that lasts less than an hour. The rudiment does not everse and its spines and podia actively tear up the larval epidermis which is progressively covered by the growing vestibular epidermis. The resulting postlarva is short-lived and morphologically similar to both the late rudiment and the early juvenile, which, however, is exotrophic. Late rudiments in E. cordatum show basic spatangoid features being bilaterally symmetric and having clavulae and sphaeridia. More importantly, they already have the convex shape and the appendage cover of early juveniles. Metamorphosis in E. cordatum appears to be less complex, i.e. no rudiment is everted, and more complete, since, in contrast to “regular” echinoids, no transitory appendages are seen. Metamorphosis/development of E. cordatum, thus, is closer to that of clypeasteroids, since the rudiment of the latter already bears juvenile definitive appendages, when everted during metamorphsis. [ABSTRACT FROM AUTHOR]

One characteristic pattern found in the marine Antarctic shallow environments is the unusually high proportion of species with protected and pelagic lecitotrophic development modes. However, species with planktotrophic development generally appear as the most conspicuous types of organisms in these environments. The Antarctic shallow benthos is considered as one of the most disturbed in the world, mainly due to the action of ice, thus one could hypothesize that such an environment should favor organisms with high dispersal capability. In order to test this general hypothesis, for two consecutive summers (2004–2005) and at two locations, we quantified the abundance and size distribution of most echinoderms present along bathymetric transects. Our results show the predominance of broadcasters (i.e., Sterechinus neumayeri and Odontaster validus) at a location where disturbances are common, while brooders (e.g., Abatus agassizii) only occurred at shallower depths of the least disturbed location. These results not only corroborate the hypothesis that local disturbance is an important factor generating these ecological patterns, but also suggest how ice-related disturbances could represent a major selecting agent behind the patterns of species diversity at an evolutionary scale in Antarctica. [ABSTRACT FROM AUTHOR]

Abstract: The impact of sedimentary conditions on the settlement, growth, and morphology of primitive spatangoid sea urchins of the genus Toxaster from the Lower Cretaceous (Valanginian and Hauterivian of the Provencal platform) is analyzed. The analyses concern spatial and temporal patterns of variation. The spatial approach is based on six isochronous populations of Toxaster granosus kiliani (424 specimens in total) dated from the Verrucosum biozone, and distributed along a proximo-distal gradient. The temporal approach concerns a reference section (Carajuan) ranging from the Lower Valanginian to the Upper Hauterivian, and involving the species T. granosus kiliani and T. gibbus. Sedimentary environments have been characterized by a factorial analysis of five characteristics of facies. Sea urchin morphology has been described with seven measures allowing the computation of two angles (α and β), and of six shape indices analyzed through a principal components analyses. The spatial approach shows that the adult mean size (> 20 mm) increases distally, and that morphology changes significantly across localities. However, only variations in α and β are sequentially organized along the proximo-distal gradient (they correspond to a forward migration of the peristome and to an expansion of the plastronal area). The stratigraphic survey of facies variation along the 369 beds analyzed in Carajuan shows a clear change in sedimentary conditions: from unstable with bioclastic events (Valanginian), to homogeneous with a low content in bioclasts (Hauterivian). Most Toxaster specimens are concentrated in three stratigraphic units (Campylotoxus and Verrucosum biozones for T. granosus kiliani; Sayni biozone for T. gibbus), their abundance being related to the macrofaunal presence and diversity and to burrowing activity. The adult mean size is only significantly related to facies variation, for the T. granosus kiliani from the Verrucosum biozone, increasing with textural gradient and bioclastic content. Shape – facies relationships have been identified for T. granosus kiliani in both Campylotoxus and Verrucosum intervals. However, the morphological variables and facies characteristics involved differ between the two biozones. The synthesis of all significant relationships between size or shape and facies characteristics demonstrates that the response of Toxaster to environmental changes was limited, and varied in space as well as for the different periods of time considered. The only recurring impact of sedimentary changes involved sea urchin abundance, that is, their ability to settle. The low adaptive potential of Toxaster is discussed in the context of the early radiation of the Spatangoida. [Copyright &y& Elsevier]

Stockley, B., Smith, A. B., Littlewood T., Lessios H. A. & MacKenzie-Dodds J. A. (2005). Phylogenetic relationships of spatangoid sea urchins (Echinoidea): taxon sampling density and congruence between morphological and molecular estimates. — Zoologica Scripta, **, ***–***. A phylogeny for 21 species of spatangoid sea urchins is constructed using data from three genes and results compared with morphology-based phylogenies derived for the same taxa and for a much larger sample of 88 Recent and fossil taxa. Different data sets and methods of analysis generate different phylogenetic hypotheses, although congruence tests show that all molecular approaches produce trees that are congruent with each other. By contrast, the trees generated from morphological data differ significantly according to taxon sampling density and only those with dense sampling (after a posteriori weighting) are congruent with molecular estimates. With limited taxon sampling, secondary reversals in deep-water taxa are interpreted as plesiomorphies, pulling them to a basal position. The addition of fossil taxa with their unique character combinations reveals hidden homoplasy and generates a phylogeny that is compatible with molecular estimates. As homoplasy levels were found to be broadly similar across different anatomical structures in the echinoid test, no one suite of morphological characters can be considered to provide more reliable phylogenetic information. Some traditional groupings are supported, including the grouping of Loveniidae, Brissidae and Spatangidae within the Micrasterina, but the Asterostomatidae is shown to be polyphyletic with members scattered amongst at least five different clades. As these are mostly deep-sea taxa, this finding implies multiple independent invasions into the deep sea. [ABSTRACT FROM AUTHOR]

Fascioles are important early-forming structures that play a key role in allowing irregular echinoids to burrow. They have traditionally been grouped into a small number of types according to their general position on the test, but this masks some significant differences that exist. The precise course that fasciole bands follow over the test plating has been mapped in detail for 89 species of spatangoid echinoids, representing the great majority of fasciole-bearing genera both living and fossil. Within each fasciole type, discrete and conserved patterns can be distinguished, differing both in which plates they are initiated on, and on whether they cross plate growth centres or are late-stage bands positioned towards the edge of the plate. Fasciole position is most highly conserved in the anterior and lateral interambulacral plates and on the earliest forming bands. The existence of different subanal fasciole patterns in the Micrasteridae and Brissidae suggests that these may have evolved independently. Schizasterid and hemiasterine spatangoids can each be subdivided into two major clades, and brissid spatangoids into three clades based on detailed patterns of their fascioles. Plotting fasciole pathways over test architecture provides a rich new source of phylogenetically informative characters. © 2005 The Linnean Society of London,Zoological Journal of the Linnean Society, 2005,144, 15−35. [ABSTRACT FROM AUTHOR]

Variations in recorded diversity over time present a scrambled signal that is modulated by a large number of variables: the potential of particular life forms to generate evolutionary innovations, external constraints induced by the environment in its broad sense, the heterogeneity of the fossil record and the analytical artefacts due to sampling bias. A key question is how to characterise and quantify the separate input of any given factor in the overall diversity signal. This paper explores the structure of diversity data for spatangoid heart urchins and the sensitivity of recorded diversity to different factors of analytical bias (length of geological periods, proportion of palaeogeographical realms explored, accessible area of outcrops and historical determinism). Unexpectedly, recorded diversity of spatangoids is not proportional to the duration of stages. Bias implied by time scale is negligible compared to bias of sampling or historical determinism. Diversity at any given time is dependent on its recent history (autocorrelation). For spatangoids, a high correlation between diversity at time ti and ti−1 suggests that recorded diversity has an evolutionary significance. A nearly constant rate of diversification is hypothesised for the Cretaceous. A relative poor fossil record during the Turonian and the Coniacian interrupts the main trend of diversification. The number of species counted for a single time interval depends on the number of palaeogeographical realms considered. In conjunction with ecological and phylogenetic data, this relation suggests an evolutionary signal in which western Tethys acted as a centre of origination. Diversity at a single location is constrained ecologically and diversification is controlled by migration into new realms. Recorded diversity and available area of outcrop seem to be correlated, but alternative interpretations can be drawn, including large-scale bias in the fossil record or operation of similar causes (e.g., effect of sea-level fluctuation). Comparing recorded diversity with separate factors independently leads to conflicting results. A multivariate approach suggests that the main trend in recorded diversity might be partially related to evolutionary signal or biases connected with the heterogeneity of the fossil record. Results from other approaches (phylogeny, morphological disparity) are consistent with and emphasise the evolutionary significance of the recorded diversity of spatangoids. [Copyright &y& Elsevier]

To investigate the influence of substrate composition on burrowing depth and respiratory funnel diameter, two species of irregular sea urchins (Spatangoida) were allowed to burrow in different substrates in laboratory experiments. The maximum burrowing depth and respiratory funnel diameters were measured. Both are dependent on substrate composition. In muddy sand the burrowing depth of Echinocardium flavescens (O. F. Müller 1776) increased as the proportion of mud in the sediment increased. The diameters of respiratory funnels were significantly smaller where the proportion of mud exceeded 50%. An exhalation current was visualized using a rhodamin solution. In Echinocardium flavescens and Brissopsis lyrifera , the exhalation current reaches the sediment surface posterior to the echinoid through a number (three to six) of small tubes. [ABSTRACT FROM AUTHOR]

A phylogenetic analysis of 36 species provides a test for the taxonomy and the history of Early Cretaceous spatangoids. Most taxonomic units from genera to suborders are consistent with the proposed phylogenetic framework. We retain Hemiasterina, Micrasterina, Hemiasteridae, Schizasteridae, Hemiaster, Heteraster, Mecaster, and Periaster as original monophyletic groups. However, all of these clades originate without the classical apomorphies normally ascribed to them. We suggest a revision of their diagnoses and of the generic attributions of basal species. Some ill-defined, ‘primitive’, and paraphyletic taxa are recognised: Toxaster, Epiaster, Palhemiaster, and Toxasteridae. Even if they do not have phylogenetic meaning, they are retained here, pending a more complete revision. [ABSTRACT FROM AUTHOR]

Focuses on a study which observed sequences of mature bindin, a biomolecule involved in reproduction, from sand dollars, heart urchins, and pencil urchins. Materials and methods; Results and discussion; Conclusions.

A procedure was developed to assess contaminated marine sediments from Dutch harbors for possible adverse biological effects using three laboratory bioassays: A 10-d survival test with the amphipod Corophium volutator, a 14-d survival test with the heart urchin Echinocardium cordatum (adults), and the bioluminescence inhibition test with the bacterium Vibrio fischeri (Microtoxt® solid phase test [SP]). Microtox results were mathematically corrected for the modifying influence of fine sediment particles. After a validation procedure on test performance and modifying factors, respectively, 81%, 99%, and 90% of the amphipod, heart urchin, and Microtox results were approved. Lower and upper threshold limits for biological effects were set at respectively 24 and 30% mortality for C. volutator, 27 and 35% mortality for E. cordatum, and 24 and 48 toxic units for the Microtox SP based on significant differences with control sediment and the performance of reference sediments. The bioassays clearly distinguished harbor sediments that give rise to acute effects and those that do not. Threshold limits for the amphipods, heart urchins, and bacteria were exceeded in, respectively, 9 to 17%, 33 to 40%, and 23 to 50% of the sediment samples. Highest effects were observed in sediments from the northerly harbors; there was significantly less response in sediments from the Delta Region and the port of Rotterdam (The Netherlands). The procedure outlined in this paper can be used for routine screening of contaminated dredged material that is proposed for open water disposal. [ABSTRACT FROM AUTHOR]

Presents a study that examined the feeding habits of the burrowing heart urchin Brissopsis lyrifera. Measurement of the water circulation and respiration rates of the heart urchin; Analysis of food selection and absorption efficiency in relation to different food sources; Estimation of the production of B. lyrifera in a carbon budget.

Examines the sediment reworking due to burrowing and feeding in the spatangoid Brissopsis lyrifera at different temperatures. Materials and methods used; Results and discussion.

Growth in the deep-sea irregular sea urchins Echinosigra phiale (family Pourtalesiidae) and Hemiaster expergitus (family Hemiasteridae) was studied from deep-sea samples taken during the years 1973 to 1985 from two stations at 2900 and 2200 m depth in the Rockall Trough (N.E. Atlantic Ocean). Growth zones, similar to those described from sea urchins in shallow water, are present as a series of wide white bands separated by narrow, dark rings in the calcite stereom of the test plates after heating to 350°C. In shallow water, such growth zones seem to result from seasonally varying growth rates. In the supposedly constant conditions in the deep sea, a seasonal growth pattern is unexpected but may occur in response to recently discovered annual pulses in downward flux of detritus from the euphotic zone, providing a seasonally varying food supply for such deposit-feeding species living in the bottom sediment. On this assumption, growth curves were fitted to counts of growth zones (as representing age in years), in the larger lateral and ventral test plates of E. phiale and H. expergitus. The opportunity was also taken to fit growth curves derived from counts of growth zones in samples of the inshore spatangoids Spatangus purpureus and Echinocardium pennatifidum. Plots of counts against test length of Echinosigra phiale and H. expergitus, although scattered and not clearly asymptotic, indicate, growth to be slower than in the two inshore spatangoids, and than in the coastal species Echinocardium cordatum, for which there are good recent growth data, available. [ABSTRACT FROM AUTHOR]

Echinocardium cordatum (Pennant, 1777) were collected in Normandy, France, in March and November 1985. The grooved frontal ambulacrum of the burrowing echinoid E. cordatum functions in transferring surface sediment from the apex to the mouth of the echinoid. Particles that fall down the burrow's chimney accumulate between the spines of the apical tuft and are taken over by specialized groove spines. Due to the slope of the groove and the type of floor spines it harbours, four successive regions can be recognized, namely the adapical region, the fasciolar region, the ambital region, and the adoral region. As a general rule aboral floor spines (i.e. club-shaped, golf-club-shaped, and isodiametric spines) function in gathering particles while propelling them mouthwards; they simultaneously embed particles in a mucous string. The oral floor spines (i.e. spatulated spines) function in hauling and guiding the mucous string towards the peribuccal area of the echinoid. Once facing the peribuccal area, particles are picked up by the peribuccal tube feet that either transfer them into the esophagus or scrape them out against the peribuccal spines. Spine-retained particles are either sucked up by the pumping action of the esophagus or fall to the burrow's floor where the tube feet may pick them up again. Together the apical tuft, the frontal groove, and the peribuccal area form an efficient food-collecting system that transfers trapped surface particles from the echinoid apex down to the mouth. Compared to that of most other spatangoids the frontal ambulacrum of E. cordatum is highly specialized. Such specialization is related to colonization of fine sediment, as is the occurrence of a chimney linking the burrow to the sediment surface. Actually the burrow's chimney is the only route for oxygen and food supply; it acts as a real ecological umbilical cord for spatangoids buried in fine sediment. [ABSTRACT FROM AUTHOR]