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This study aims to investigate the spatial and seasonal impacts on the biochemical responses of two bioindicators: Tridacna squamosa and Echinometra mathaei which inhabit the Red Sea coast of Egypt. Samples were collected from three sites during the summer of 2019 and the winter of 2020. Total protein, MDA, and enzyme activity of pyruvate kinase (PK) and lactate dehydrogenase (LDH) were measured in the gonads of the collected samples. The results confirmed that environmental variables vary at both spatial and seasonal levels, where the two species exhibited different patterns of biochemical response to internal and external stresses. In addition, both studied species did not resort to anaerobic respiration as a defense mechanism. Therefore, this study confirms that the use of biomarkers in the field shall be regarded as a general warning of internal and external stress. [ABSTRACT FROM AUTHOR]

Fossil echinoids have rarely been described from Iran. This study focuses on the echinoid fauna found in the Cretaceous strata (Kazhdumi Formation) of the Geno and Gerash sections in the Bandar Abbas and Fars areas of the Zagros Mountains, southern Iran. The age of the Kazhdumi Formation in both sections is determined to be Albian-Cenomanian based on the associated ammonites and microfauna, its stratigraphic position, and previous studies on this formation. Twenty-one echinoid species (twelve regular and nine irregular) belonging to seventeen genera were described in this study. Fourteen of these species are reported for the first time from Iran. In addition, a new diadematoid echinoid species, Arabicodidema jafariani sp. nov. is introduced. New age ranges are proposed for Pliotoxaster comanchei and Lambertiaster douvillei. The paleogeographic position of the Zagros Basin in the Tethyan realm is confirmed based on the distribution of the index species. [ABSTRACT FROM AUTHOR]

A new rhabdocoel of the genus Syndesmis Silliman, 1881 (Umagillidae) is described from the intestine of the New Zealand sea urchin Evechinus chloroticus (Valenciennes, 1846) Mortensen, 1943a. This new species, Syndesmis kurakaikina n. sp., is morphologically distinct and can easily be recognised by its very long (±1 mm) stylet and its bright-red colour. In addition to providing a formal description, we present some observations on reproduction and life history of this new species. Fecundity is comparable to that of other umagillids and the rate of egg production and development increases with temperature. Hatching in this species is induced by intestinal fluids of its host. Relevant to global warming, we assessed the effect of temperature on survival, fecundity, and development. The tests indicate that Syndesmis kurakaikina n. sp. is tolerant of a wide range of temperatures (11–25 °C) and that its temperature optimum lies between 18.0 and 21.5 °C. Egg viability is, however, significantly compromised at the higher end of this temperature range, with expelled egg capsules often being deformed and showing increasingly lower rates of hatching. Given this, a rise in global temperature might increase the risk of Syndesmis kurakaikina n. sp. infecting new hosts and would possibly facilitate the spread of these endosymbionts. Image 1 • Syndesmis kurakaikina n. sp. (Umagillidae, Rhabdocoela) is described. • This new species was found infecting kina (Evechinus chloroticus) in New Zealand. • S. kurakaikina n. sp. can tolerate a wide range of temperatures. • Egg-capsule production and development increase with temperature. • Rising sea-water temperatures may facilitate infection and spread of this species. [ABSTRACT FROM AUTHOR]

The rarity of certain taxa in the type Devonian, south-west England, may be real, but it is probably, in part, an artefact of preservation. In part this is a product of Variscan deformation, but disarticulation of multi-element skeletons into minute plates must also be a contributory factor. Echinoids are rare from these deposits and were hitherto limited to the Upper Devonian. A single radiole (=spine) from the Middle Devonian (Givetian) Lummaton Shell Beds, Torquay Limestone Formation, is referred to echinoid sp. indet. Although stromatoporoids are common in these same beds, true sponges were hitherto unknown. In the same rock specimen, a moderately well preserved siliceous spicule is referred to octactinellid sp. indet. [ABSTRACT FROM AUTHOR]

Based on representatives of the Late Cretaceous genus Gauthieria ( Gauthieria radiata – Gauthieria spatulifera – Gauthieria princeps ), ontogenetic trajectories within the family Phymosomatidae are described for the first time. Due to shared similarities in their ontogenetic development, an intimate evolutionary relationship must be assumed. This interpretation is most supported by analyses of the development in the ambulacral plating pattern (alternation of simple plates and compound plates), which is not commonly found among the Phymosomatoidae. This pattern, however, is present among all three species during development. The developmental trajectories of 8 further characters were included in this study (arrangement of the adapical pore pairs, number of pore pairs, pore pair numbers in ambital ambulacral plates, number of interambulacral plates, peristomal opening, apical opening diameter, test height, radial ornament of the areoles). The evolution in this lineage is characterised by several different heterochronic processes, which suggest a dissociated heterochronic evolution, indicating a developmental modularity. Additionally, the systematic treatment of G. princeps is discussed on account of the presented results. [ABSTRACT FROM AUTHOR]

Abstract: Field work in the Lower Cretaceous of the Dolomites (Italy) has resulted in the recovery of a new genus of ‘disasteroid’ echinoid, which successively was also discovered in slightly older strata in Northern Hungary. This new genus, Absurdaster, is characterized by its highly modified, disjunct apical disc in which all genital plate except genital plate 2 are reduced or fused. The gonopores (which may be multiple) have shifted and pierce interambulacral plates. Anteriorly ambulacrum III is distinctly sunken and forms a distinct frontal notch, while the posterior end is pointed and features a small sharply defined posterior face bearing the periproct. Two new species are established: Absurdaster puezensis sp. nov. from the Upper Hauterivian to Lower Barremian Puez Formation of Northern Italy is characterized by its rudimentary ambulacral pores in the paired ambulacra, high hexagonal ambulacral plates aborally and multiple gonopores in the most adapical plates of interambulacral columns 1b and 4a. Absurdaster hungaricus sp. nov. from the Lower Hauterivian Bersek Marl Formation of Northern Hungary, in contrast, shows circumflexed ambulacral pores, low ambulacral plates, a single gonopore each in the most adapical plates of interambulacral columns 1b and 4a and a flaring posterior end, with sharp margin and invaginated periproct. In addition to those two species Collyrites meriani Ooster, 1865 from the uppermost Berriasian to basal Barremian of Switzerland is attributed to the new genus. Despite the poor knowledge on this form it seems to be distinguished from the new species by its smaller ambulacral plates and higher interambulacral/ambulacral plate ratio. Phylogenetic analyses based on previous work by Barras (2007) and Saucède et al. (2007) indicate that the new genus is a highly derived stem-group member of the Atelostomata close to the split of holasteroids and spatangoids. A combined analysis based on a subset of the characters employed in these two studies for the first time results in a fully resolved tree for ‘disasteroids’. Absurdaster, shows two notable morphological peculiarities: 1) it is one of the first echinoids to develop fascioles and exhibits a yet unknown type of fasciole circling the periproct, termed circumanal fasciole here; 2) it is extraordinary among echinoderms as its extraxial skeleton is reduced to a single plate, the madreporite (genital plate 2), and because its genital pores pierce axial elements rather than extraxial ones. [Copyright &y& Elsevier]

The article presents a study on determining the role of a barnacle, Austrobalanus imperator, in creating species-rich patches in a species-poor landscape in southeastern Australia. It notes that two experiments were conducted wherein barnacle density was modified. The focus of the first experiment is the establishment of habitats on vertical rock surfaces which involves the addition of barnacles in densities from zero, low, medium and high. There was a significant increase in invertebrate cover and diversity after the addition of barnacles at the given densities. The persistence of sessile invertebrates following the removal of barnacles from well-established assemblages dominated by sponges were assessed by the second experiment.

Sea urchins have been model organisms for the study of fertilization for more than a century. Fertilization in sea urchins happens externally, which facilitates the study of sperm-egg attachment and fusion, and means that all of the molecules involved in gamete recognition and fusion are associated with the gametes. Sea urchin sperm bindin was the first "gamete recognition protein" to be isolated and characterized (Vacquier and Moy 1977), and bindin has since been studied by developmental biologists interested in fertilization, by biochemists interested in membrane fusion and by evolutionary biologists interested in reproductive isolation and speciation. Research on bindin was last reviewed thirteen years ago by Vacquier et al. (1995) in an article titled "What have we learned about sea urchin sperm bindin?" in which the authors reviewed the identification, isolation and early molecular examinations of bindin. Research since then has focused on bindin's potential role in fusing egg and sperm membranes, comparisons of bindin between distantly related species, studies within genera linking bindin evolution to reproductive isolation, and studies within species looking at fertilization effects of individual bindin alleles. In addition, the egg receptor for bindin has been cloned and sequenced. I review this recent research here. [ABSTRACT FROM AUTHOR]

Abstract: Newly collected specimens of an uncommon and poorly known irregular echinoid, Nucleopygus (Jolyclypus) jolyi, are recorded from Cenomanian strata in Charentes (western France). The first examples of this echinoid to have been described date back to the late nineteenth century; those specimens (i.e., the types) appear to have been lost. What particularly distinguishes this taxon from other Cenomanian echinoids is the singular combination of derived and plesiomorphic morphological characters, the latter being reminiscent of Jurassic irregular echinoids. Derived features concern the appendages, employed in locomotion and feeding, whereas ancestral characters involve the apical system and periproct. This peculiarity has led previous workers to include this echinoid in the stem-group Galeropygidae, which would imply a >40-myr gap in the stratigraphic range of this group or, alternatively, challenge the stratigraphic provenance of the taxon. A detailed examination of newly collected material has now allowed us to resolve the apparent discrepancies, describe a reversal and document sexual dimorphism as well. A phylogenetic analysis was carried out in order to revise the systematic position of the taxon, now transferred to the Cretaceous genus Nucleopygus. A neotype is designated. [Copyright &y& Elsevier]

For short development species, like the sea urchin Heliocidaris erythrogramma , the entire planktonic duration can be impacted by marine heatwaves (MHW). Developmental thermal tolerance of this species through metamorphosis was investigated over a broad range (7.6–28.0 °C), including temperatures across its distribution and MHW conditions. In controls (19.5–21.0 °C), 80% of individuals developed to metamorphosis at day 5, doubling to 10 days at 14.0 °C. The thermal range (14.4–21.2 °C) of metamorphosis on day 7 reflected the realised thermal niche with 25.9 °C the upper temperature for success (T 40). By day 10, juvenile tolerance narrowed to the local range (16.2–19.0 °C), similar to levels tolerated by adults, indicating negative carryover effects across the metamorphic transition. Without phenotypic adjustment or adaptation, regional warming will be detrimental, although populations may be sustained by thermotolerant offspring. Our results show the importance of the metamorphic transition in understanding the cumulative sensitivity of species to MHW. • Marine heatwaves (MHW) are becoming pervasive and can impact planktonic stages. • For fast developing species the full planktonic duration can be impacted by a MHW. • In Heliocidaris erythrogramma MHW had negative carryover effects for juveniles. • The metamorphic transition is key in understanding the species' sensitivity to MHW. [ABSTRACT FROM AUTHOR]