Search

Heart urchins (Echinoidea: Spatangoida) collectively represent a highly diverse group of echinoids with abundant global fossil and extant records. Despite their wide distribution, the preservation challenges associated with their delicate and thin tests have led to limited comprehensive studies of this fossil group in Taiwan. Here, we report a new spatangoid echinoid assemblage from the Early Pleistocene part of the Gutingkeng Formation. Despite the inherent fragility and pronounced deformations in the studied specimens, the preserved key diagnostic characteristics (pore pairs in ambulacrum III and oral plating) indicate most of the fossil echinoids belong to genera Schizaster and Brissopsis. Moreover, based on detailed taphonomic and functional morphological examination, the paleoenvironment of the assemblage is interpreted as a low-energy, fine-grained soft substrate in a deeper shallow-water setting. Furthermore, this assemblage shares a high similarity with Assemblage 3 at the S'Archittu-Cajaragas section in the Miocene of Sardinia, supporting the notion that echinoids are excellent paleoenvironmental indicators, as similar echinoid faunas can be found across continents when environmental conditions are similar. On the other hand, the temporal and geographical distribution of Schizaster -rich echinoid assemblages in Taiwan may be correlated with the Cenozoic orogeny history of Taiwan. [ABSTRACT FROM AUTHOR]

The sea urchin Pseudechinus magellancus exhibits a covering behaviour through which it captures different items from the environment and arranges them on its aboral surface with the assistance of podia. The items mainly used include detached algae and inorganic items available in the substrate. Spatial (between sites) and vertical (along a coastal depth gradient from intertidal tidepools to upper circalittoral zones) variability was found in the composition of covering items, indicating that coverage is strongly influenced by the availability of the utilised items. Inorganic biogenic items (eg shell remnants) were prevalent in the lower intertidal, while detached algae predominate in subtidal environments. A positive selection of larger items from those available in the environment was found at least in the intertidal tidepools. The species exhibited an equal degree of coverage between juveniles and adults, and also a higher proportion of individuals with high coverage in the intertidal zone compared to the subtidal zone. The degree of coverage between sites with dissimilar sediment input was similar. The covering behaviour in P. magellanicus may not be a response to a single factor but rather an advantageous trait with multiple functions that could have been selected simultaneously. [ABSTRACT FROM AUTHOR]

ABSTRACT Drilling predation on echinoids (sea urchins) has been known to occur in marine ecosystems since the Jurassic Period; however, it has rarely been studied in existing species. Tests of the irregular sea urchin Brissus unicolor (Leske, 1778), which frequently occurs in shallow substrates of the Canary Islands, mostly show very evident perforations through their skeletons. The aim of this study was to describe the characteristics of these perforations in order to determine their possible origins as well as document their size, site selectivity, and frequency of occurrence among different sample sites. Of the 104 tests of B. unicolor that were collected from 15 locations off the island of Tenerife (Canary Islands, Spain), 94% showed a least one perforation. These boreholes exhibit a circular morphology, penetrating the sea urchin tests perpendicularly and entirely. Notably, they display a unique acid signature, diverging from those documented in the fossil record and other relevant studies. Our analysis showed size and site selectivity by the predator as the perforations were mainly located on the oral side of the test. The perforations are attributed to drilling predation. The characteristics of these boreholes on B. unicolor match published records of predation marks suggesting that they are produced by the predatory gastropod family Cassidae, with Semicassis undulata (Gmelin, 1791) considered to be the most probable predator. [ABSTRACT FROM AUTHOR]

Hitherto unreported whale fall fauna has been found from the Lower Miocene of Khari Nadi Formation of Kutch, India.This vertebrate-invertebrate assemblage comprises jumbled up bone fragments of different parts of the whale along with molluscs and echinoids. Some representatives in this assemblage are characteristic whale fall fauna and some are characteristic shallow marine fauna. The molluscs belong to the families Buccinidae, Provannidae, Naticidae, Turritellidae, Borsoniidae, Volutidae, Haminoeidae, Cypraeidae, Strombidae, Rostelleriidae, Cassidae, Osteridae, Veneridae, Astartidae and the echinoids to family Spatangidae and Schizasteridae. The present study reveals that the deposition of this entire assemblage was in a shallow marine environment and also sheds some light on the molluscan association related to a whale fall from the western Indian sea waters in the Lower Miocene. [ABSTRACT FROM AUTHOR]

Gregory's diverticulum, a digestive tract structure unique to a derived group of sand dollars (Echinoidea: Scutelliformes), is filled with sand grains obtained from the substrate the animals inhabit. The simple methods of shining a bright light through a specimen or testing response to a magnet can reveal the presence of a mineral-filled diverticulum. Heavy minerals with a specific gravity of >2.9 g/cm3 are selectively concentrated inside the organ, usually at concentrations one order of magnitude, or more, greater than found in the substrate. Analyses of diverticulum content for thirteen species from nine genera, using optical mineralogy, powder X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, as well as micro-computed tomography shows the preference for selection of five major heavy minerals: magnetite (Fe3O4), hematite (Fe2O3), ilmenite (FeTiO3), rutile (TiO2), and zircon (ZrSiO4). Minor amounts of heavy or marginally heavy amphibole, pyroxene and garnet mineral grains may also be incorporated. In general, the animals exhibit a preference for mineral grains with a specific gravity of >4.0 g/ cm3, although the choice is opportunistic and the actual mix of mineral species depends on the mineral composition of the substrate. The animals also select for grain size, with mineral grains generally in the range of 50 to 150 mm, and do not appear to alter this preference during ontogeny. A comparison of analytical methods demonstrates that X-ray attenuation measured using micro-computed tomography is a reliable non-destructive method for heavy mineral quantification when supported by associated analyses of mineral grains extracted destructively from specimens or from substrate collected together with the specimens. Commonalities in the electro-chemical surface properties of the ingested minerals suggest that such characteristics play an important role in the selection process. [ABSTRACT FROM AUTHOR]

Gregory’s diverticulum, a digestive tract structure unique to a derived group of sand dollars (Echinoidea: Scutelliformes), is filled with sand grains obtained from the substrate the animals inhabit. The simple methods of shining a bright light through a specimen or testing response to a magnet can reveal the presence of a mineral-filled diverticulum. Heavy minerals with a specific gravity of >2.9 g/cm3 are selectively concentrated inside the organ, usually at concentrations one order of magnitude, or more, greater than found in the substrate. Analyses of diverticulum content for thirteen species from nine genera, using optical mineralogy, powder X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, as well as micro-computed tomography shows the preference for selection of five major heavy minerals: magnetite (Fe3O4), hematite (Fe2O3), ilmenite (FeTiO3), rutile (TiO2), and zircon (ZrSiO4). Minor amounts of heavy or marginally heavy amphibole, pyroxene and garnet mineral grains may also be incorporated. In general, the animals exhibit a preference for mineral grains with a specific gravity of >4.0 g/cm3, although the choice is opportunistic and the actual mix of mineral species depends on the mineral composition of the substrate. The animals also select for grain size, with mineral grains generally in the range of 50 to 150 μm, and do not appear to alter this preference during ontogeny. A comparison of analytical methods demonstrates that X-ray attenuation measured using micro-computed tomography is a reliable non-destructive method for heavy mineral quantification when supported by associated analyses of mineral grains extracted destructively from specimens or from substrate collected together with the specimens. Commonalities in the electro-chemical surface properties of the ingested minerals suggest that such characteristics play an important role in the selection process.

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate taxonomy and descriptions of species are key to understanding biodiversity. The echinoid genus Tripneustes is an ecologically and commercially important taxon that includes the tropical Tripneustes gratilla gratilla and the recently described T. kermadecensis from Australia and New Zealand. While examining the Australian Museum collections to clarify the distributions of these two species in eastern Australia we found potential senior type material for T. kermadecensis. These specimens from Sydney Harbour were originally described in 1878 as Evechinus australiae by Tenison-Woods but neither illustrated nor redescribed in any subsequent report. We undertook molecular and morphological analysis of these specimens to determine whether T. kermadecensis and E. australiae represent two distinct taxa or not. This included micro-computed tomography, quantification of test traits and molecular genetic analysis. The COI sequence and morphology of Evechinus australiae matched that of Tripneustes kermadecensis. As such, T. kermadecensis is a junior synonym of Evechinus australiae. The correct designation of this taxon is therefore Tripneustes australiae (Tenison-Woods, 1878). [ABSTRACT FROM AUTHOR]

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.

An echinoderm fauna from the San Salvatore Formation (Middle Triassic, Southern Alps) is here described in detail for the first time. Identifiable crinoids and echinoids were collected from three different localities: Mt. San Salvatore (Ticino, Switzerland), Rasa di Varese and San Michele (Lombardy, Italy). Crinoid taxa include Encrinus cf. aculeatus, Holocrinus sp. indet., Zardinicrinus cf. granulosus, Encrinidae gen. et sp. indet. Echinoid taxa include “Cidaris” cf. roemeri, Serpianotiaris sp. indet., Triadocidaris transversa, Triadocidaris sp. indet., and an indetermined form (Cidaridae). Most of the material was collected from Rasa di Varese, along with a rich upper Anisian ammonoid and conodont fauna, belonging to the upper Reitzi Zone and the Secedensis Zone. Migration of crinoids have been documented during the upper Anisian (from upper Pelsonian to lower Illyrian), mainly from the westernmost Tethyan Realm northward to the Germanic basin. Crinoid taxa already reported in the lower and upper Illyrian of the Germanic basin have also been collected, dated here to the late Illyrian (upper Reitzi Z.-Secedensis Z.) suggesting that several taxa migrated southwards in the Tethys realm during the late Illyrian. [ABSTRACT FROM AUTHOR]

Sea urchins play a key role in the marine environment, contributing to maintain a balance in benthic ecosystems. Toxopneustes roseus acts as a regulator of rhodolith beds and is a key species as a bioturbation promoter, while Rhyncholampas pacificus moderates the detritus content of sediment through various mechanisms and contributes to accelerating the circulation of organic matter. However, nothing is known about their early development, so the objective of this research is to characterize the embryonic and larval development of specimens of the two species from the southern Mexican Pacific and identify the causes that produce their differences. The embryonic development of T. roseus lasted approximately 20 ​h; the echinopluteus larva appeared at 23 ​h and culminated in around 12 days with an eight-armed larva. Metamorphosis was reached at 18 days. The embryonic development of R. pacificus lasted about 15 ​h; the larva emerged at 20 ​h and culminated in about two days with an eight-armed larva. The metamorphosis was completed in 9 days. The reproductive output of both species determines their development time and the structure of their larvae; therefore, the energy of R. pacificus is invested in reaching metamorphosis earlier to ensure that its larvae, which are not very abundant, settle and recruit to the population. Regarding T. roseus , the longest permanence in the plankton is efficiently maintained by its numerous larvae through the presence of mobile arms and the shift of the swimming function to the epauletes. This is the first work that characterizes the early development of a species of the genus Toxopneustes and of the only living species of the genus Ryncholampas. The information generated in this work is essential to gaining knowledge about these groups of echinoids, especially the effect of the environment on their early development. [Display omitted] • R pacificus invests its energy in reaching metamorphosis and settlement earlier. • T roseus maintains its larvae in the plankton for longer, using structural accessories. • The early development of a species of Toxopneustes is characterized for the first time. • The early development of the only extant species of Ryncholampas is characterized for the first time. [ABSTRACT FROM AUTHOR]

The identification of species present in an ecosystem and the assessment of a faunistic inventory is the first step in any ecological survey and conservation effort. Thanks to technological progress, DNA barcoding has sped up species identification and is a great support to morphological taxonomy. In this work, we used a "Reverse Taxonomy" approach, where molecular (DNA barcoding) analyses were followed by morphological (skeletal features) ones to determine the specific status of 70 echinoid and 22 crinoid specimens, collected during eight different expeditions in the Ross and Weddell Seas. Of a total of 13 species of sea urchins, 6 were from the Terra Nova Bay area (TNB, Ross Sea) and 4 crinoids were identified. Previous scientific literature reported only four species of sea urchins from TNB to which we added the first records of Abatus cordatus (Verrill, 1876), Abatus curvidens Mortensen, 1936 and Abatus ingens Koehler, 1926. Moreover, we found a previous misidentification of Abatus koehleri (Thiéry, 1909), erroneously reported as A. elongatus in a scientific publication for the area. All the crinoid records are new for the area as there was no previous faunistic inventory available for TNB. [ABSTRACT FROM AUTHOR]

Echinoids represent an important component of the Cenozoic marine benthic communities. Their diversity in the Mediterranean area is reviewed within the Late Miocene–Recent, a period of remarkable paleogeographic and paleoclimate changes. Of the 37 genera that lived during the Late Miocene, only Holaster, Pliolampas, and Trachyaster did not survive the Messinian Mediterranean salinity crisis (MSC), indicating that this event was not as drastic as for other marine groups. The presence of Brissopsis within the uppermost Messinian testifies to the existence of fully marine conditions at least towards the end of the MSC. Severe drops in the echinoid diversity, involving the loss of 40% of the Pliocene genera, occurred during the Piacenzian, likely because of the onset of the Northern Hemisphere glaciation. Most of the echinoid extinctions correlate with the crisis of the Mediterranean bivalve assemblage recorded at about 3 Ma. The Early Pleistocene progressive cooling caused the disappearance of further thermophilous shallow-water genera (Clypeaster, Schizechinus, Echinolampas) and allowed the entrance of temperate taxa (Paracentrotus lividus, Placentinechinus davolii and Sphaerechinus granularis) from the Atlantic. Some deep-water taxa (Histocidaris sicula, Stirechinus scillae, Cidaris margaritifera), whose Recent relatives are currently restricted to tropical areas, are not found in the area after the Calabrian possibly because of the disappearance of the psychrosphere. The extant Mediterranean echinoid fauna mainly derives from the Late Miocene fauna, reduced after several climatic changes by about 43% at the genus level. The recent increase of the sea surface temperatures allowed the entrance of the Lessepsian Diadema setosum and confined the deep-water species of Holanthus to the coldest areas of the basin, making this genus endangered.

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]

Loose limestone blocks of a newly recognized hydrocarbon-seep deposit from the lower Oligocene Jansen Creek Member of the Makah Formation were collected on a beach terrace close to the mouth of Bullman Creek in Washington State, USA. The limestone consists largely of authigenic carbonate phases, including 13C-depleted fibrous cement forming banded and botryoidal crystal aggregates with δ13C values as low as –23.5 ‰. Lipids extracted from the limestone yielded molecular fossils of anaerobic methanotrophic archaea (ANME), dominated by compounds of an ANME-2/DSS consortium with δ13C values as low as −106 ‰, indicating formation at an ancient methane seep. The fossil inventory of the seep deposit is remarkable, consisting almost solely of echinoid remains, whereas typical seep biota are absent. Varying preservation of the echinoid fossils indicates parautochthonous deposition, corroborated by evidence for high fluid flow at the ancient seep, possibly responsible for displacement of echinoids after death. Although a full taxonomic description of the echinoids cannot be given, almost all fossils were assigned to one taxon of irregular spatangoids, except for a single regular echinoid. Abundance and lifestyle of the irregular spatangoids in the Bullman Creek echinoid seep deposit resemble those of the fossil Tithonia oxfordiana from an upper Jurassic seep deposit in France and extant Sarsiaster griegii from modern seeps in the Gulf of Mexico. The Bullman Creek echinoid deposit probably represents a fossil analogue of the Gulf of Mexico Sarsiaster mass occurrence, indicating that the adaptation of spatangoid echinoids to chemosynthesis-based ecosystems ranges back at least to the earliest Oligocene. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract This study presents the first record of the cordiform echinoid Plagiobrissus grandis (Gmelin, 1791) (Echinoidea: Spatangoida: Brissidae) in Paraná’s shallow inner shelf, in addition to a brief description of its location, body measurements, sex determination, and reproductive status. Two specimens were recorded between 2015 (bycatch by artisanal fishing) and 2016 (observed by scuba diving). The only specimen - with severe signs of weakness - captured was donated to Associação MarBrasil and kept in an aquarium for rehabilitation (8 days), where it was possible to observe digging movements, burying skills (partially), and camouflage or covering behavior. The organism was sent to the UNESPAR campus of Paranaguá and was photographed, measured (length: 155.65 mm, width: 118.93 mm, and maximum test height: 41.31 mm), fixed, and properly preserved. Digitized images of the histological preparation showed that it was a female in the recovery stage (or nutritional reserve) of the reproductive cycle. Regardless of their limitations, the current records for the Brissidae family in South Atlantic are still concentrated on the Brazilian coast, contributing to the understanding of zoogeographic, ecological, morphophysiological, and behavioral aspects of the spatangoid echinoids.

An echinoderm fauna from the San Salvatore Formation (Middle Triassic, Southern Alps) is here described in detail for the first time. Identifiable crinoids and echinoids were collected from three different localities: Mt. San Salvatore (Ticino, Switzerland), Rasa di Varese and San Michele (Lombardy, Italy). Crinoid taxa include Encrinus cf. aculeatus, Holocrinus sp. indet., Zardinicrinus cf. granulosus, Encrinidae gen. et sp. indet. Echinoid taxa include “Cidaris” cf. roemeri, Serpianotiaris sp. indet., Triadocidaris transversa, Triadocidaris sp. indet., and an indetermined form (Cidaridae). Most of the material was collected from Rasa di Varese, along with a rich upper Anisian ammonoid and conodont fauna, belonging to the upper Reitzi Zone and the Secedensis Zone. Migration of crinoids have been documented during the upper Anisian (from upper Pelsonian to lower Illyrian), mainly from the westernmost Tethyan Realm northward to the Germanic basin. Crinoid taxa already reported in the lower and upper Illyrian of the Germanic basin have also been collected, dated here to the late Illyrian (upper Reitzi Z.-Secedensis Z.) suggesting that several taxa migrated southwards in the Tethys realm during the late Illyrian.

Despite the great utility of nanoparticles (NPs) in water remediation, their effects on marine ecosystems are unknown and unpredictable. The toxicity of the most used nanoparticles, such as ZnO, Ag, and TiO2 on the purple sea urchin, Paracentrotus lividus (Lamarck, 1816), has been demonstrated by several authors. The aim of this study was to evaluate the effects of TiO2 sol-gel and TiO2-rGO nanocompounds on both vitality and motility of spermatozoa of P. lividus. The spermatozoa were exposed at different times (30 and 60 min) and concentrations (10, 20, 40 µg/mL) of both nano-TiO2 compounds. The results clearly showed a decrease in both vitality and motility of P. lividus spermatozoa exposed. In particular, vitality and motility were inversely related to both exposure time and concentration of TiO2 sol-gel and TiO2-rGO nanocompounds. [ABSTRACT FROM AUTHOR]

A critical reassessment of foraminiferan parasitism on echinoid hosts, past and present, identifies all previous records as doubtful and circumstantial evidence as being limited to possible foraminiferan bioerosion traces on a Late Cretaceous Echinocorys perconicus host from Northern Germany. Here, we report on a second type of putative foraminiferan attachment trace fossils found on a Late Cretaceous Echinocorys jaekeli from the Danish Basin, and establish the new ichnogenus and ichnospecies Solichnus aestheticus within the ichnofamily Centrichnidae. These delicate sun-shaped etchings are diagnosed as bowl-shaped circular depressions, wider than deep, from which numerous open canals radiate in a meandering fashion, ramify, and thin out. The canals indicate a mutual avoidance pattern with those of neighbouring specimens and they circumvent the areoles of the echinoid's primary tubercles. We interpret the central depression as anchoring site of a foraminiferan test and the radiating canals, formed right at the interface of the stereom and epithelium, as the work of its long and ramifying pseudopodia. The symbiotic relationship was probably of parasitic nature (sensu stricto), with the foraminiferan feeding on the organic tissue of the epithelium (epithelium browsing) and profiting from protection offered by the host's spines and defensive pedicellariae. The echinoid survived the infestation and formed skeletal regeneration textures that clearly identify the association as syn vivo. The high degree of specialisation required to infest an echinoid host and form the complex attachment trace might suggest that the pronounced rarity of the trace is not a case of a false host but of host specificity. The identity of the foraminiferan parasite remains unknown, although the bioerosion traces show some affinity to those of the extant species Cymbaloporella tabellaeformis and Gypsina vesicularis. [ABSTRACT FROM AUTHOR]

The phylum Echinodermata comprising the classes Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea, and Crinodeia, is one of the important invertebrate groups. Members of this phylum live exclusively in marine habitats and are distributed in almost all depths and latitudes. Some of them, such as sea urchins and sea cucumbers, are commercially valuable and constitute a major fishery resource. Echinoderms are increasingly recognized as a unique source of various metabolites with a wide range of biological activities. The importance of dietary polyunsaturated fatty acids, such as eicosapentaenoic acid, in human health has drawn attention to echinoderms as a promising source of essential fatty acids (FAs). Extensive information on the FAs of the phylum has been accumulated to date. The biosynthetic capabilities and feeding habits of echinoderms explain the findings of the unusual FAs in them. Certain common and unusual FAs may serve as chemotaxonomic markers of the classes. The main goal of the review was to gather the relevant information on the distribution of FAs among the echinoderm classes, describe the structures, distribution, biosynthetic pathways, and bioactivity, with an emphasis on the FAs specific for echinoderms. A large part of the review is devoted to the FAs derived from echinoderms that exhibit various biological activities promising for potential therapeutic applications. [ABSTRACT FROM AUTHOR]

Ocean warming and acidification driven by anthropogenic CO 2 emissions may impact the mineral composition of marine calcifiers. Species with high skeletal Mg content could be more susceptible in polar regions due to the increased solubility of CO 2 at lower temperatures. We aimed to assess the environmental influence on skeletal Mg content of Antarctic echinoderms belonging to Asteroidea, Ophiuroidea, Echinoidea and Holothuroidea classes, along a latitudinal gradient from the South Shetland Islands to Rothera (Adelaide Island). We found that all skeletal structures, except for echinoid spines, exhibited high Mg content, with asteroids showing the highest levels. Our results suggest that asteroids and holothuroids exert a higher biological capacity to regulate Mg incorporation into their skeletons. In contrast, the variability observed in the skeletal Mg content of ophiuroids and echinoids appears to be more influenced by local environmental conditions. Species-specific differences in how environmental factors affect the skeletal Mg content can thus be expected as a response to global climate change. • Skeletal structures presented high Mg content, except in echinoid spines. • Asteroids had the highest Mg content, followed by ophiuroids, holothuroids, and echinoids. • No local variability in skeletal Mg content was observed in asteroids and holothuroids. • Environmental parameters may have influenced the skeletal Mg in ophiuroids and echinoids. [ABSTRACT FROM AUTHOR]

Echinoids represent an important component of the Cenozoic marine benthic communities. Their diversity in the Mediterranean area is reviewed within the Late Miocene-Recent, a period of remarkable paleogeographic and paleoclimate changes. Of the 37 genera that lived during the Late Miocene, only Holaster, Pliolampas, and Trachyaster did not survive the Messinian Mediterranean salinity crisis (MSC), indicating that this event was not as drastic as for other marine groups. The presence of Brissopsis within the uppermost Messinian testifies to the existence of fully marine conditions at least towards the end of the MSC. Severe drops in the echinoid diversity, involving the loss of 40% of the Pliocene genera, occurred during the Piacenzian, likely because of the onset of the Northern Hemisphere glaciation. Most of the echinoid extinctions correlate with the crisis of the Mediterranean bivalve assemblage recorded at about 3 Ma. The Early Pleistocene progressive cooling caused the disappearance of further thermophilous shallow-water genera (Clypeaster, Schizechinus, Echinolampas) and allowed the entrance of temperate taxa (Paracentrotus lividus, Placentinechinus davolii and Sphaerechinus granularis) from the Atlantic. Some deep-water taxa (Histocidaris sicula, Stirechinus scillae, Cidaris margaritifera), whose Recent relatives are currently restricted to tropical areas, are not found in the area after the Calabrian possibly because of the disappearance of the psychrosphere. The extant Mediterranean echinoid fauna mainly derives from the Late Miocene fauna, reduced after several climatic changes by about 43% at the genus level. The recent increase of the sea surface temperatures allowed the entrance of the Lessepsian Diadema setosum and confined the deep-water species of Holanthus to the coldest areas of the basin, making this genus endangered. [ABSTRACT FROM AUTHOR]

Echinodermata pada dasarnya merupakan indikator kesehatan dan status dari terumbu karang di laut. Dasar perairan yang landai dengan substrat pasir, terumbu karang, dan pecahan karang merupakan habitat bagi hewan jenis Asteroidea, Echinoidea, dan Teripang. Penelitian ini bertujuan untuk mengidentifikasi jenis-jenis bintang laut (Asteroidea), bulu babi (Echinoidea), dan teripang (Holothuroidea) dari perairan Pulau Tunda, Kabupaten Serang. Pengamatan Asteroidea, Echinoidea, dan Holothuroidea menggunakan metode line transek yang dimodifikasi, yaitu mengamati subjek dalam jarak yang sama sepanjang garis transek dan kuadrat transek dengan pengamatan 2,5 m di sebelah kanan dan kiri garis line transek. Observasi habitat yang meliputi substrat dan kedalaman, sedangkan jumlah total bintang laut, bulu babi, dan teripang di setiap stasiun dicatat yang selanjutnya sampel didokumentasikan dan diidentifikasi berdasarkan ciri-ciri morfologinya. Di perairan Pulau Tunda ditemukan 2 spesies dari kelas Asteroidea yaitu Linckia laevigata dan Culcita novaeguneae, 3 spesies dari Echinoidea yaitu Diadema antilarum, Diadema setosum, Echinomerta mathaei, dan 3 spesies dari Holothuroidea yaitu Holothuria atra, Holothuria leucospilota, Bohadschia graeffei.

The identification of species present in an ecosystem and the assessment of a faunistic inventory is the first step in any ecological survey and conservation effort. Thanks to technological progress, DNA barcoding has sped up species identification and is a great support to morphological taxonomy. In this work, we used a “Reverse Taxonomy” approach, where molecular (DNA barcoding) analyses were followed by morphological (skeletal features) ones to determine the specific status of 70 echinoid and 22 crinoid specimens, collected during eight different expeditions in the Ross and Weddell Seas. Of a total of 13 species of sea urchins, 6 were from the Terra Nova Bay area (TNB, Ross Sea) and 4 crinoids were identified. Previous scientific literature reported only four species of sea urchins from TNB to which we added the first records of Abatus cordatus (Verrill, 1876), Abatus curvidens Mortensen, 1936 and Abatus ingens Koehler, 1926. Moreover, we found a previous misidentification of Abatus koehleri (Thiéry, 1909), erroneously reported as A. elongatus in a scientific publication for the area. All the crinoid records are new for the area as there was no previous faunistic inventory available for TNB.

Echinoids are an important component in benthic marine environments, which occur at all depths from the shallow-water hard substrates to abyssal depths. To date, the phylogeny of the sea urchins and the macro-evolutionary processes of deep-sea and shallow water groups have not yet been fully resolved. In the present study, we sequenced the complete mitochondrial genomes (mitogenomes) of four deep-sea sea urchins (Echinoidea), which were the first representatives of the orders Aspidodiadematoida, Pedinoida and Echinothurioida, respectively. The gene content and arrangement were highly conserved in echinoid mitogenomes. The tRNA-SerAGY with DHU arm was detected in the newly sequenced echinoid mitogenomes, representing an ancestral structure of tRNA-SerAGY. No difference was found between deep-sea and shallow water groups in terms of base composition and codon usage. The phylogenetic analysis showed that all the orders except Spatangoida were monophyletic. The basal position of Cidaroida was supported. The closest relationship of Scutelloida and Echinolampadoida was confirmed. Our phylogenetic analysis shed new light on the position of Arbacioida, which supported that Arbacioida was most related with the irregular sea urchins instead of Stomopneustoida. The position Aspidodiadematoida (((Aspidodiadematoida C Pedinoida) C Echinothurioida) C Diadematoida) revealed by mitogenomic data discredited the hypothesis based on morphological evidences. The macro-evolutionary pattern revealed no simple onshore-offshore or an opposite hypothesis. But the basal position of the deep-sea lineages indicated the important role of deep sea in generating the current diversity of the class Echinoidea. [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]

Echinoids are an important component in benthic marine environments, which occur at all depths from the shallow-water hard substrates to abyssal depths. To date, the phylogeny of the sea urchins and the macro-evolutionary processes of deep-sea and shallow water groups have not yet been fully resolved. In the present study, we sequenced the complete mitochondrial genomes (mitogenomes) of four deep-sea sea urchins (Echinoidea), which were the first representatives of the orders Aspidodiadematoida, Pedinoida and Echinothurioida, respectively. The gene content and arrangement were highly conserved in echinoid mitogenomes. The tRNA-SerAGY with DHU arm was detected in the newly sequenced echinoid mitogenomes, representing an ancestral structure of tRNA-SerAGY. No difference was found between deep-sea and shallow water groups in terms of base composition and codon usage. The phylogenetic analysis showed that all the orders except Spatangoida were monophyletic. The basal position of Cidaroida was supported. The closest relationship of Scutelloida and Echinolampadoida was confirmed. Our phylogenetic analysis shed new light on the position of Arbacioida, which supported that Arbacioida was most related with the irregular sea urchins instead of Stomopneustoida. The position Aspidodiadematoida (((Aspidodiadematoida + Pedinoida) + Echinothurioida) + Diadematoida) revealed by mitogenomic data discredited the hypothesis based on morphological evidences. The macro-evolutionary pattern revealed no simple onshore-offshore or an opposite hypothesis. But the basal position of the deep-sea lineages indicated the important role of deep sea in generating the current diversity of the class Echinoidea.

The Ordovician Period witnessed the first evidence of appearance of all modern echinoderm clades as well as it is the most concentrated interval of echinoderm diversity in Earthâs history. This knowledge is largely based on reports from Baltica, Avalonia, Laurentia and Gondwana. However, the Ordovician record of sea cucumbers (Holothuroidea) and their allies, like echinoids and ophiocistioids (Echinozoa), is sparse and patchy. The earlier published Cambrian or Ediacaran records of echinozoan echinoderms (e.g., sea cucumbers) are based on misinterpreted specimens of other phyla. Neither the origins of the Echinozoa nor the split of holothuroids from ophiocistioids or echinoids are properly understood. One reason for this is the fact that less than 100 (articulated) Ordovician specimens of sea urchins, sea cucumbers and ophiocistioids have been recovered worldwide so far. In general, fossil remains of the Holothuroidea are limited to (1) innumerable microscopic and/or mesoscopic ossicles of the body wall, (2) five distinct calcareous plates which supported the anus in some (more highly evolved) sea cucumber groups, and (3) a total of usually ten radial and interradial elements of the calcareous ring surrounding the pharynx. The latter represents a synapomorphy for the entire group and is important in the higher-level group systematics. In addition, to date, there are only about two dozen known Phanerozoic localities (Konservat-Lagerstätten and obrution deposits) that have yielded (4) articulated body fossils of holothurians. Few attempts have been made to use disarticulated fossils of Echinodermata to understand the distribution, diversity and early radiation of Holothuroidea, Echinoidea and Ophiocistioidea. Only during the last two decades, advanced micropalaeontological and macropalaeontological techniques have been combined to investigate these understudied echinoderm groups in greater detail. This will help to gain further understanding about the Early Palaeozoic echinozoan echinoderms. In this presentation, a short overview of known holothurian finds (mostly from Baltica) is given.

For marine ectotherms, larval success, planktonic larval duration and dispersal trajectories are strongly influenced by temperature, and therefore, ocean warming and heatwaves have profound impacts on these sensitive stages. Warming, through increased poleward flow in regions with western boundary currents, such as the East Australia Current (EAC), provides opportunities for range extension as propagules track preferred conditions. Two sea urchin species, Centrostephanus rodgersii and Heliocidaris tuberculata, sympatric in the EAC warming hotspot, exhibit contrasting responses to warming. Over half a century, C. rodgersii has undergone marked poleward range extension, but the range of H. tuberculata has not changed. We constructed thermal performance curves (TPC) to determine if contrasting developmental thermal tolerance can explain this difference. The temperatures tested encompassed present‐day distribution and forecast ocean warming/heatwave conditions. The broad and narrow thermal optimum (Topt) ranges for C. rodgersii and H. tuberculata larvae (7.2 and 4.7°C range, respectively) matched their realized (adult distribution) thermal niches. The cool and warm temperatures for 50% development to the feeding larva approximated temperatures at adult poleward range limits. Larval cool tolerances with respect to mean local temperature differed, 6.0 and 3.8°C respectively. Larval warm tolerances were similar for both species as are the adult warm range edges. The larvae of both species would be sensitive to heatwaves. Centrostephanus rodgersii has stayed in place and shifted in space, likely due to its broad cold–warm larval thermal tolerance and large thermal safety margins. Phenotypic plasticity of the planktonic stage of C. rodgersii facilitated its range extension. In contrast, larval cold intolerance of H. tuberculata explains its restricted range and will delay poleward extension as the region warms. In a warming ocean, we show that intrinsic thermal biology traits of the pelagic stage provide an integrative tool to explain species‐specific variation in range shift patterns. [ABSTRACT FROM AUTHOR]

Sea urchins is marine organism from Phylum Echinoderms which have high economic and ecological value. Therefore, we need data on the current condition of sea urchins, especially those in the Spermonde Islands. Through this research, it is hoped that the community structure and distribution of sea urchins in Kodingareng Lompo Island, Spermonde Islands can be known. The sampling method used was quadrant transects measuring 5x5 meters on 4 plots in the seagrass area on Kodingareng Lompo Island. The data analysis used was species composition, density, relative density, diversity index, and uniformity index. The results obtained show that there are three species of sea urchins, namely Diadema setosum, Mespilia globulus, and Tripneustes gratilla, basen on morphology identification. Diadema setosum is species with the highest species composition value, namely 92%. The density value (0.017 individuals / m2) and the diversity of sea urchins (H '

El presente estudio se realizó en la zona intermareal en el Refugio de Vida Silvestre- Río Escalante Chacocente, municipio de Santa Teresa. Su objetivo principal es la determinación de la asociación de las especies Arbacia lixula y Ophiocomina nigra en función de variables físico-químicas en estratos rocosos. Se cuantificó la diversidad de las especies Arbacia lixula y Ophiocomina nigra, mediante índices de diversidad biológica, equitabilidad, riqueza específica y su distribución en ecosistemas rocosos mediante Patrones de distribución Espacio Temporal. Los muestreos se realizaron en dos épocas (seca y lluviosa), de enero a junio en el año 2018, en 5 estratos rocosos en la playa de Chacocente. La recolección de las muestras se realizó a través de un marco metálico de 1 m2. Se determinó las variables físico-químicas (Temperatura, Salinidad, pH y OD). La estructura comunitaria de los ecosistemas estuvo conformada por 3 Phylum: Echinodermata (Clase Echinoidea y Ophiuroidea), Mollusca (Clase Bivalvia y Gasterópoda) y Arthropoda (Clase Malacostraca), teniendo 26485 organismos en las dos épocas de muestreo. La menor densidad, se encontró en la época seca (2.99 ind/m2) y la mayor en invierno con 3.5 ind/m2. La abundancia y distribución de las especies fue heterogéneo en los estratos rocosos. Con el índice de Jaccard y Morisita-Horn, presentaron alta similitud entre los estratos rocosos. La especie más abundante fue la Arbacia lixula, teniendo mayor capacidad de adaptación a los diferentes cambios que ocurren en los ecosistemas rocosos que la Ophiocomina nigra. En cuanto a la composición, distribución y asociación de las especies presentaron relación con las variables fisicoquímicas del agua, mar, en donde las variaciones y fluctuaciones determinan que ambas especies se adaptan perfectamente a los cambios, permitiéndoles asociarse. En cuanto a su importancia ecológica, estas especies, son buenos indicadores de la calidad ecosistémica, permitiendo el reclutamiento de nuevas especies en los ecosistemas rocosos.

A new species of sea urchin is described from deposits assigned to the Kössen Formation (uppermost Triassic, Rhaetian) of Vorarlberg, Austria. A comparison with other fossil echinoids has shown that the available specimen can be assigned to the genus Orthopsis. Moreover, several distinctive features of the material allow it to be described here as a new species, O. kiseljaki sp. nov. The new species is the stratigraphically earliest representative of the genus and the first to be recorded from the Triassic, although a considerably higher family level diversity of Echinoidea does not occur until the beginning of the Jurassic Period. The new finding from the Kössen Formation implies that the Rhaetian might be an important time for the diversification of echinoids, particularly with regard to the echinacean Orthopsis. [ABSTRACT FROM AUTHOR]

Copyright of Spanish Journal of Palaeontology is the property of Socieadad Espanola de Paleontologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The oldest carbonate sediments in the western Eucla Basin in south-western Australia are a series of cool-water bryozoan-dominated bioclastic grainstones, packstones and marls that represent deposition during the Tortachilla Transgression during the Bartonian (middle Eocene) planktonic foraminiferal zones 14-15. The two principal units are the Nanarup Limestone and a unit reported here for the first time and named, informally, the Manypeaks limestone. These units contain rich invertebrate faunas dominated by bryozoans, echinoids, bivalves and brachiopods. Herein we document fourteen echinoid species that occur in these limestones. They comprise one cidaroid, one camarodont, one salenioid, two cassiduloids, one echinolampadoid, one clypeasteroid and seven spatangoids. Four new species are described, the cassiduloid Eurhodia westaustraliae sp. nov., the clypeasteroid Fossulaster susae sp. nov., and the spatangoids Cyclaster jamiei sp. nov. and Gillechinus kaitae sp. nov. The species of Fossulaster represents the earliest known member of the Fossulasteridae and the earliest known record of a marsupiate echinoid in Australia. Analysis of the middle and late Eocene echinoids faunas of the western Eucla Basin establishes that the Nanarup Limestone echinoid fauna represents the cassiduloid biofacies, while the Manypeaks limestone is a mixed cassiduloid and spatangoid biofacies. [ABSTRACT FROM AUTHOR]

Copyright of Atti della Società dei Naturalisti e Matematici di Modena is the property of Societa dei Naturalisti e Matematici di Modena and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Echinoids are key components of modern marine ecosystems. Despite a remarkable fossil record, the emergence of their crown group is documented by few specimens of unclear affinities, rendering their early history uncertain. The origin of sand dollars, one of its most distinctive clades, is also unclear due to an unstable phylogenetic context. We employ 18 novel genomes and transcriptomes to build a phylogenomic dataset with a near-complete sampling of major lineages. With it, we revise the phylogeny and divergence times of echinoids, and place their history within the broader context of echinoderm evolution. We also introduce the concept of a chronospace – a multidimensional representation of node ages – and use it to explore methodological decisions involved in time calibrating phylogenies. We find the choice of clock model to have the strongest impact on divergence times, while the use of site-heterogeneous models and alternative node prior distributions show minimal effects. The choice of loci has an intermediate impact, affecting mostly deep Paleozoic nodes, for which clock-like genes recover dates more congruent with fossil evidence. Our results reveal that crown group echinoids originated in the Permian and diversified rapidly in the Triassic, despite the relative lack of fossil evidence for this early diversification. We also clarify the relationships between sand dollars and their close relatives and confidently date their origins to the Cretaceous, implying ghost ranges spanning approximately 50 million years, a remarkable discrepancy with their rich fossil record.

Despite the great utility of nanoparticles (NPs) in water remediation, their effects on marine ecosystems are unknown and unpredictable. The toxicity of the most used nanoparticles, such as ZnO, Ag, and TiO2 on the purple sea urchin, Paracentrotus lividus (Lamarck, 1816), has been demonstrated by several authors. The aim of this study was to evaluate the effects of TiO2 sol-gel and TiO2-rGO nanocompounds on both vitality and motility of spermatozoa of P. lividus. The spermatozoa were exposed at different times (30 and 60 min) and concentrations (10, 20, 40 µg/mL) of both nano-TiO2 compounds. The results clearly showed a decrease in both vitality and motility of P. lividus spermatozoa exposed. In particular, vitality and motility were inversely related to both exposure time and concentration of TiO2 sol-gel and TiO2-rGO nanocompounds.

Sea urchins have a wide variety of symbionts on their body surfaces and inside their bodies. Copepods of the genus Clavisodalis (Taeniacanthidae) collected from the esophagus of sea urchins of the genera Diadema and Echinothrix in southern Japan were identified based on their morphological characteristics, and molecular analysis was conducted to determine whether genetic variation occurs in copepods from different localities and hosts. Morphological observations identified individuals from southern Japan as Clavisodalis sentifer Dojiri and Humes, 1982, making this the first record of this species in the northern hemisphere and the first record of its genus in Japan. Morphological and molecular analysis suggested that the copepod specimens collected from multiple hosts across two genera would be the same species. Considering the typically observed high level of host specificity among taeniacanthid copepods, the utilization of hosts from two genera by C. sentifer is noteworthy.

We sequenced the complete mitochondrial genome of sand dollar Astriclypeus mannii (Verrill 1867) (Echinoidea: Astriclypeidae) occurring in the subtidal sand flat in Jeju Island off the south coast of Korea. The mitochondrial genome was 15,744 bp in length and contained 13 protein-coding genes (PCGs), 22 transfer RNAs, two ribosomal RNAs, and 140 nucleotides representing the putative control region. We reconstructed the concatenated phylogenetic tree based on 13 PCGs of 18 echinoderms, including A. mannii. From the maximum likelihood clustering, A. mannii was grouped in the order Echinolampadacea. The complete mitochondrial sequence of A. mannii for the first time in this study provide valuable insight in understanding the evolution and phylogenetic analysis of echinoids (sea urchins).

Complex life cycles have evolved independently numerous times in marine animals as well as in disparate algae. Such life histories typically involve a dispersive immature stage followed by settlement and metamorphosis to an adult stage on the sea floor. One commonality among animals exhibiting transitions of this type is that their larvae pass through a 'precompetent' period in which they do not respond to localized settlement cues, before entering a 'competent' period, during which cues can induce settlement. Despite the widespread existence of these two phases, relatively little is known about how larvae transition between them. Moreover, recent studies have blurred the distinction between the phases by demonstrating that fluid turbulence can spark precocious activation of competence. Here, we further investigate this phenomenon by exploring how larval interactions with turbulence change across ontogeny, focusing on offspring of the sand dollar Dendraster excentricus (Eschscholtz). Our data indicate that larvae exhibit increased responsiveness to turbulence as they get older. We also demonstrate a likely cost to precocious competence: the resulting juveniles are smaller. Based upon these findings, we outline a new, testable conception of competence that has the potential to reshape our understanding of larval dispersal and connectivity among marine populations.

Sea urchins possess specialized adhesive organs, tube feet. Although initially believed to function as suckers, it is currently accepted that they rely on adhesive and de-adhesive secretions to attach and detach repeatedly from the substrate. Given the biotechnological potential of their strong reversible adhesive, sea urchins are under investigation to identify the protein and glycan molecules responsible for its surface coupling, cohesion and polymerization properties. However, this characterization has only focused on a single species, Paracentrotus lividus. To provide a broader insight into sea urchins adhesion, a comparative study was performed using four species belonging to different taxa and habitats: Diadema africanum, Arbacia lixula, Paracentrotus lividus and Sphaerechinus granularis. Their tube feet external morphology and histology was studied, together with the ultrastructure of their adhesive secretory granules. In addition, one antibody and five lectins were used on tube foot histological sections and extracts, and on adhesive footprints to detect the presence of adhesion-related (glyco)proteins like those present in P. lividus in other species. Results confirmed that the antibody raised against P. lividus Nectin labels the adhesive organs and footprints in all species. This result was further confirmed by a bioinformatic analysis of Nectin-like sequences in ten additional species, increasing the comparison to seven families and three orders. The five tested lectins (GSL II, WGA, STL, LEL, and SBA) demonstrated that there is high interspecific variability of the glycans involved in sea urchin adhesion. However, there seems to be more conservation among taxonomically closer species, like P. lividus and S. granularis. In these species, lectin histochemistry and lectin blots indicated the presence of high molecular weight putative adhesive glycoproteins bearing N-acetylglucosamine residues in the form of chitobiose in the adhesive epidermis and footprints. Our results emphasize a high selective pressure for conservation of functional domains in large putative cohesive proteins and highlight the importance of glycosylation in sea urchin adhesion with indications of taxonomy-related conservation of the conjugated glycans.

Introduction: Central America, a narrow strip of land dividing the Atlantic and Pacific oceans, has a high diversity of marine and terrestrial species. Echinoderms are one of the most diverse marine groups with 420 reported species. Objective: To summarize echinoderm research in Central America. Methods: We compiled the literature from SCOPUS, Web of Science, SciELO, Google Scholar, Biodiversity Heritage Library, the Internet Archive and the Smithsonian Library. Results: We found 324 publications dating from 1840 to 2020; the early studies had a strong taxonomic focus, but after the 1970s, ecology, evolution and reproduction gained prominence. Echinoidea is the most studied class (38% of publications) due to its use in evolutionary studies as well as the importance of the genus Diadema in reef ecology and dynamics. Conclusion: We recommend more research on fisheries management, conservation and environmental education; and greater integration of local and international research.

In this paper we present the first record of well preserved specimens of Gitolampas subrotundus (Cotteau, 1856) from the Late Paleocene of Iran (Jorasan Razavi county, northeast Iran). the detailed biostratigraphic and calcareous nannofossils investigations were carried out on a stratigraphic section in Chehel Formation. this study extends the palaeogeographical distribution of Late Paleocene echinids along the northern tethyanmargins. the investigated fossiliferous section is compared with coeval strata from other european regions.

Flexible resource investment is a risk sensitive reproductive strategy where individuals trade resources spent on reproduction for basic metabolic maintenance and survival. This study examined morphological variation in herbivorous sea urchin grazers across a mosaic landscape of macroalgae dominated habitats interspersed with patches of sea urchin barrens to determine whether sea urchins shift energy allocation in response to food limitation. Extensive underwater surveys of habitat attributes (e.g., sea urchin density, algae cover) were paired with detailed laboratory assays (e.g., sea urchin dissections) to determine how resource abundance affects energy allocation between reproductive capacity and body structure in the purple sea urchin, Strongylocentrotus purpuratus. We found that: (1) sea urchins had a more elongate jaw structure relative to body size in habitats void of macroalgae (i.e., barrens), (2) sea urchin reproductive capacity (i.e., gonad index) was lower in barrens and the barrens habitat was primarily comprised of encrusting algae, and (3) sea urchin jaw morphology (i.e., lantern index) and reproductive capacity (i.e., gonad index) were inversely related. These results suggest that sea urchins respond to macroalgae limited environments by shifting energy allocation between reproductive capacity and modifications of the foraging apparatus, which may explain the ability of sea urchins to acquire food in resource-limited environments.

Adaptive landscapes are a common way of conceptualizing the phenotypic evolution of lineages across deep time. Although multiple approaches exist to implement this concept into operational models of trait evolution, inferring adaptive landscapes from comparative datasets remains challenging. Here, I explore the macroevolutionary dynamics of echinoid body size using data from over 5000 specimens and a phylogenetic framework incorporating a dense fossil sampling and spanning approximately 270 million years. Furthermore, I implement a novel approach of exploring alternative parameterizations of adaptive landscapes that succeeds in finding simpler, yet better‐fitting models. Echinoid body size has been constrained to evolve within a single adaptive optimum for much of the clade's history. However, most of the morphological disparity of echinoids was generated by multiple regime shifts that drove the repeated evolution of miniaturized and gigantic forms. Events of body size innovation occurred predominantly in the Late Cretaceous and were followed by a drastic slowdown following the Cretaceous‐Paleogene mass extinction. The discovery of these patterns is contingent upon directly sampling fossil taxa. The macroevolution of echinoid body size is therefore characterized by a late increase in disparity (likely linked to an expansion of ecospace), generated by active processes driving lineages toward extreme morphologies. [ABSTRACT FROM AUTHOR]