Common Cenozoic Echinoids from Florida

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Differentiation of the genital apparatus in juvenile echinoids (Paracentrotus lividus)

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Annotated checklist of the umagillid turbellarians infesting echinoids (Echinodermata)

A literature survey of the taxonomically complex taxon Syndesmis Silliman, 1881 is presented, resulting in the recognition of 22 valid species and three species mentioned in several works but not yet described. For each of these species the host(s) are mentioned and the distribution is given. These results are compared with earlier checklists and the differences are discussed.

Temperature effects on larval growth and survival in five species of Caribbean Echinoids

Under the global change scenario, the possible effects of ocean warming were investigated on the larvae of five species of Caribbean Echinoids: Echinometra lucunter, Echinometra viridis, Clypeaster rosaceus, Tripneustes ventricosus and Lytechinus williamsi. Their thermal tolerance was evaluated rearing them for six days under different temperature regimes (26, 28, 30, 32, 34, 36°C). The larval sensitivity to the treatments was evaluated on the base of survival and growth. The rearing at higher temperatures has revealed a great suffering state of the larvae by inducing both reduction of live larvae and abnormality in their development. The extent of impact of the treatments varied from species to species, evidencing different levels of thermal tolerance. Anyway, higher temperature treatments have shown a general lethal threshold at about 34°C for most of the species. As an exception, the lethal threshold of Echinometra species was 36°C, few larvae of which being still capable of survive at the temperature of 34°C. The studies have also analyzed the effect of water warming on the larvae growth in terms of size and symmetry. The results put in evidence the presence of a critical upper temperature (about 32°C) at which the larvae of all species reveal a great suffering state that translates in the reduction of size (i.e., of body, stomach and postero-dorsal arm) and abnormalities (i.e., strong difference in the lengths of the two postero-dorsal arms). As sea surface temperatures are predicted to increase of 4-5°C by 2100, the high percentage of abnormal larvae and their scarce survival observed at 32- 34°C treatments indicate that the early stages of these species could be affected by future global warming.

Effects of acute temperature increase on performance and survival of Caribbean echinoids

Climate change is occurring at a faster rate than in the past, with an expected increase of mean sea surface temperatures up to 4.8°C by the end of this century. The actual capabilities of marine invertebrates to adapt to these rapid changes has still to be understood. Adult echinoids play a crucial role in the tropical ecosystems where they live. Despite their role, few studies about the effect of temperature increase on their viability have been reported in literature. This thesis work reports a first systematic study on several Caribbean echinoids about their tolerance to temperature rise in the context of global warming. The research - carried out at the Bocas del Toro Station of the Smithsonian Tropical Research Institute, in Panama - focalized on the 6 sea urchins Lytechinus variegatus, L. williamsi, Echinometra lucunter, E. viridis, Tripneustes ventricosus and Eucidaris tribuloides, and the 2 sand dollars Clypeaster rosaceus and C. subdepressus. Mortality and neuromuscular well-being indicators - such as righting response, covering behaviour, adhesion to the substrate, spine and tube feet movements - have been analysed in the temperature range 28-38°C. The righting time RT (i.e., the time necessary for the animal to right itself completely after inversion) measured in the 6 sea urchin species, demonstrated a clearly dependence on the water temperature. The experiments allowed to determine the “thermal safety margin” (TSM) of each species. Echinometra lucunter and E. viridis resulted the most tolerant species to high temperatures with a TSM of 5.5°C, while T. ventricosus was the most vulnerable with a TSM of only 3°C. The study assessed that all the species already live at temperatures close to their upper thermal limit. Their TSMs are comparable to the predicted temperature increase by 2100. In absence of acclimatization to such temperature change, these species could experience severe die-offs, with important consequences for tropical marine ecosystems.

Tertiary echinoids of the Carrizo Creek region in the Colorado Desert.

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Evolution of developmental gene regulatory networks in echinoids

Developmental gene regulatory networks (dGRNs) are assemblages of regulatory genes that direct embryonic development of animal body plans and their morpho-logical structures. dGRNs exhibit recursively-wired circuitry that is encoded in the genome and executed during development. Alteration to the regulatory architecture of dGRNs causes variation in developmental programs both during the development of an individual organism and during the evolution of an individual lineage. The ex-planatory power of these networks is best exemplified by the global dGRN directing early development of the euechinoid sea urchin Strongylocentrotus purpuratus. This network consists of numerous regulatory genes engaging in hundreds of genomic regulatory transactions that collectively direct the delineation of early embryonic domains and the specification of cell lineages. Research on closely-related euechi-noid sea urchins, e.g. Lytechinus variegatus and Paracentrotus lividus, has revealed marked conservation of dGRN architecture in echinoid development, suggesting little appreciable alteration has occurred since their divergence in evolution at least 90 million years ago (mya).

We sought to test whether this observation extends to all sea urchins (echinoids) and undertook a systematic analysis of over 50 regulatory genes in the cidaroid sea urchin Eucidaris tribuloides, surveing their regulatory activity and function in a sea urchin that diverged from euechinoid sea urchins at least 268 mya. Our results revealed extensive alterations have occurred to all levels of echinoid dGRN archi-tecture since the cidaroid-euechinoid divergence. Alterations to mesodermal sub-circuits were particularly striking, including functional di˙erences in specification of non-skeletogenic mesenchyme (NSM), skeletogenic mesenchyme (SM), and en-domesodermal segregation. Specification of endomesodermal embryonic domains revealed that, while their underlying network circuitry had clearly diverged, regu-latory states established in pregastrular embryos of these two groups are strikingly similar. Analyses of E. tribuloides specification leading to the estab-lishment of dorsal-ventral (aboral-oral) larval polarity indicated that regulation of regulatory genes expressed in mesodermal embryonic domains had incurred significantly more alterations than those expressed in endodermal and ectodermal domains. Taken together, this study highlights the ability of dGRN architecture to buffer extensive alterations in the evolution and early development of echinoids and adds further support to the notion that alterations can occur at all levels of dGRN architecture and all stages of embryonic development.

Complete mitochondrial genome of the sea cucumber Apostichopus japonicus (Echinodermata: Holothuroidea): The first representative from the subclass Aspidochirotacea with the echinoderm ground pattern

Complete mitochondrial genome plays an important role in the accurate revelation of phylogenetic relationships among metazoans. Here we present the complete mitochondrial genome sequence from a sea cucumber Apostichopus japonicus (Echinodermata: Holothuroidea), which is the first representative from the subclass Aspidochirotacea. The mitochondrial genome of A. japonicus is 16,096 bp in length. The heavy strand consists of 31.8% A, 20.2% C, 17.9% G, and 30.1% T bases (AT skew = 0.027: GC skew = 0.062). It contains thirteen protein-coding genes (PCGs), twenty-two transfer RNA genes, and two ribosomal RNA genes. There are a total of 3793 codons in all thirteen mitochondrial PCGs, excluding incomplete termination codons. The most frequently used amino acid is Leu (15.77%), followed by Set (9.73%), Met (8.62%), Phe (7.94%), and Ala (7.28%). Intergenetic regions in the mitochondrial genome of A. japonicus are 839 bp in total, with three relatively large regions of Unassigned Sequences (UAS) greater than 100 bp. The gene order of A. japonicus is identical to that observed in the five studied sea urchins, which confirms that the gene order shared by the two classes (Holothuroidea and Echinoidea) is a ground pattern of echinoderm mitochondrial genomes. Bayesian tree based on the cob gene supports the following relationship: (outgroup, (Crinoids, (Asteroids, Ophiuroids, (Echinoids, Holothuroids)))). (C) 2009 Elsevier B.V. All rights reserved.

Spatial vision in the purple sea urchin Strongylocentrotus purpuratus (Echinoidea).

Recent evidence that echinoids of the genus Echinometra have moderate visual acuity that appears to be mediated by their spines screening off-axis light suggests that the urchin Strongylocentrotus purpuratus, with its higher spine density, may have even more acute spatial vision. We analyzed the movements of 39 specimens of S. purpuratus after they were placed in the center of a featureless tank containing a round, black target that had an angular diameter of 6.5 deg. or 10 deg. (solid angles of 0.01 sr and 0.024 sr, respectively). An average orientation vector for each urchin was determined by testing the animal four times, with the target placed successively at bearings of 0 deg., 90 deg., 180 deg. and 270 deg. (relative to magnetic east). The urchins showed no significant unimodal or axial orientation relative to any non-target feature of the environment or relative to the changing position of the 6.5 deg. target. However, the urchins were strongly axially oriented relative to the changing position of the 10 deg. target (mean axis from -1 to 179 deg.; 95% confidence interval +/- 12 deg.; P<0.001, Moore's non-parametric Hotelling's test), with 10 of the 20 urchins tested against that target choosing an average bearing within 10 deg. of either the target center or its opposite direction (two would be expected by chance). In addition, the average length of the 20 target-normalized bearings for the 10 deg. target (each the vector sum of the bearings for the four trials) were far higher than would be expected by chance (P<10(-10); Monte Carlo simulation), showing that each urchin, whether it moved towards or away from the target, did so with high consistency. These results strongly suggest that S. purpuratus detected the 10 deg. target, responding either by approaching it or fleeing it. Given that the urchins did not appear to respond to the 6.5 deg. target, it is likely that the 10 deg. target was close to the minimum detectable size for this species. Interestingly, measurements of the spine density of the regions of the test that faced horizontally predicted a similar visual resolution (8.3+/-0.5 deg. for the interambulacrum and 11+/-0.54 deg. for the ambulacrum). The function of this relatively low, but functional, acuity - on par with that of the chambered Nautilus and the horseshoe crab - is unclear but, given the bimodal response, is likely to be related to both shelter seeking and predator avoidance.

Is the Species Flock Concept Operational? The Antarctic Shelf Case

There has been a significant body of literature on species flock definition but not so much about practical means to appraise them. We here apply the five criteria of Eastman and McCune for detecting species flocks in four taxonomic components of the benthic fauna of the Antarctic shelf: teleost fishes, crinoids (feather stars), echinoids (sea urchins) and crustacean arthropods. Practical limitations led us to prioritize the three historical criteria (endemicity, monophyly, species richness) over the two ecological ones (ecological diversity and habitat dominance). We propose a new protocol which includes an iterative fine-tuning of the monophyly and endemicity criteria in order to discover unsuspected flocks. As a result nine « full » species flocks (fulfilling the five criteria) are briefly described. Eight other flocks fit the three historical criteria but need to be further investigated from the ecological point of view (here called « core flocks »). The approach also shows that some candidate taxonomic components are no species flocks at all. The present study contradicts the paradigm that marine species flocks are rare. The hypothesis according to which the Antarctic shelf acts as a species flocks generator is supported, and the approach indicates paths for further ecological studies and may serve as a starting point to investigate the processes leading to flock-like patterning of biodiversity. © 2013 Lecointre et al.

Ranking of length-class seasonal and regional effects on dietary compositions of the co-occurring Pagrus auratus (Sparidae) and Pseudocaranx georgianus (Carangidae)

Using an effective combination of multivariate testing and ordination analyses, this study compares the extents to which the diets of two co-occurring fish species (Pagrus auratus and Pseudocaranx georgianus) are related to body size (length class), season and region and the rank order importance of those effects. Thus, volumetric dietary compositions were determined for these species on the lower west coast of Australia, where both are abundant, and for P. auratus from the mid west coast and P. georgianus from the south coast. The diet of P. auratus on the lower west coast was strongly related to body size and slightly less to season. With increasing body size, its diet shifted from predominantly ophiuroids to larger prey, such as brachyuran crabs, teleosts, echinoids and ultimately asteroids, probably reflecting a shift from foraging over soft sediments to areas over and around reefs. Seasonal changes on the lower west coast were restricted mainly to small P. auratus, while larger fish underwent seasonal changes further north. Analyses using a common size range of medium to larger P. auratus demonstrated that dietary composition differed more between regions than seasons. The relationships between diet and length class of P. georgianus on both the lower west and south coasts were less pronounced than for P. auratus and seasonal changes were restricted to the south coast, where amphipod consumption increased markedly in summer. The diet of P. georgianus was related far more to region than length class and season, with more small teleosts, small crabs, carideans and littorinids and less amphipods, isopods and small bivalves being ingested on the lower west than south coasts. Although crabs and teleosts were important typifying prey of P. auratus and P. georgianus, when co-occurring, the former predator tended to ingest greater volumes of larger and often less mobile prey. This reflects differences in dentition, jaw morphology and feeding behaviour and reduces the potential for competition for food resources. The results imply that P. auratus and P. georgianus are opportunistic feeders and that the effects of length class, season and region on dietary composition and their rank orders can vary markedly between species and for length class and season between regions for the same species.

Spatangoid-produced ichnofabrics (Bateig Limestone, Miocene, Spain) and the preservation of spatangoid trace fossils

A spatangoid-produced ichnofabric is described from the Miocene Bateig Limestone, SE Spain. This ichnofabric is characterized by the dominant presence of large meniscate burrows (Bichordites) produced by irregular echinoids. This constitutes an unusual mode of occurrence for spatangoid bioturbation, as their traces are most typically preserved in bases and tops of sandstone event beds. In fact, despite their important role as burrowers in modern settings (that can be extended back to the Early Cretaceous based on their body fossil record), spatangoid trace fossils (Scolicia and Bichordites) are comparatively rare. Several factors play an important role in their preservation: mechanism of burrowing, sediment characteristics, early diagenesis and presence/absence of deep-tier burrowers. Spatangoid-produced ichnofabrics, such as those from the Bateig Limestone, characterize depositional settings with intermittent deposition of event beds where there is an absence of deeper-tier bioturbation. (C) 2008 Elsevier B.V. All rights reserved

An ichnofabric approach to the depositional interpretation of the intensely burrowed Bateig Limestone, Miocene, SE Spain

The foraminiferal-rich pelagic Bateig Limestone forms several varieties of the important building stones quarried at Bateig Hill in southeastern Spain. Three principal ichnofabrics (Bichordites, mottled-Palaeophycus and mottled-Ophiomorpha) are recognized, which are present in at least two (possibly up to four) repeated successions (cycles). Each succession begins with an erosional event. The Bichordites ichnofabric represents a new type of facies, formed as thin turbidity/grain flow, stratiform units derived from sediment slips off a fault into deep water. Each slipped unit became almost completely bioturbated by infaunal echinoids, colonizing by lateral migration. Because of the thinness of the units, successive colonizations tended to truncate the underlying burrows giving rise to a pseudo-stratification. As the Bichordites ichnofabric accumulated on the fault apron, thus reducing the effective height of the fault scarp, the substrate gradually came under the influence of currents traversing the shelf. This led to a change in hydraulic regime, and to the mottled-Palaeophycus and mottled-Ophiomorpha ichnofabrics in sediment deposited under bed load transport, and associated with laminar and cross-stratified beds and local muddy intervals. Reactivation of the fault triggered erosion and channeling and a return to grain flow sedimentation, and to the Bichordites ichnofabric of the succeeding cycle. The highest unit of the Bateig Limestone is formed entirely of cross-stratified calcarenites with occasional Ophiomorpha (Ophiomorpha-primary lamination ichnofabric) and is similar to many shallow marine facies but they still bear a significant content of pelagic foraminifera. The sedimentary setting bears resemblance with that described for the Pleistocene Monte Torre Paleostrait and the modem Strait of Messina (Italy), where the narrow morphology of the depositional area enhanced tidal currents and allowed for high-energy sandy deposition in relatively deep areas. More data on the Miocene paleogeography of the Bateig area should provide further testing for this hypothesis. The ichnofacies and stacking of the Bateig Limestone differ from the classic Seilacherian model in that they reflect changes in hydraulic process and are associated with faulting and subsidence and changes in sediment supply. Recognition of the unusual ichnofabrics and their relationships provides a clear indication of the overall dynamic setting. (c) 2006 Elsevier B.V. All rights reserved.

Resposta comportamentiais do ouriço-do-mar preto a pistas químicas que indicam risco de predação

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)