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Human consumption of sea urchin gonads has led to overexploitation of commercial species, and the search for new marketable species to promote the recovery of exploited populations. Echinometra van...

Shifts in microbial communities represent a rapid response mechanism for host organisms to respond to changes in environmental conditions. Therefore, they are likely to be important in assisting the acclimatization of hosts to seasonal temperature changes as well as to variation in temperatures across a species' range. The Persian/Arabian Gulf is the world's warmest sea, with large seasonal fluctuations in temperature (20℃ - 37℃) and is connected to the Gulf of Oman which experiences more typical oceanic conditions (32℃ in the summer). This system is an informative model for understanding how symbiotic microbial assemblages respond to thermal variation across temporal and spatial scales. Here, we elucidate the role of temperature on the microbial gut community of the sea urchin Echinometra sp. EZ and identify microbial taxa that are tightly correlated with the thermal environment. We generated two independent datasets with a high degree of geographic and temporal resolution. The results show that microbial communities vary across thermally variable habitats, display temporal shifts that correlate with temperature, and can become more disperse as temperatures rise. The relative abundances of several ASVs significantly correlate with temperature in both independent datasets despite the300 km distance between the furthest sites and the extreme seasonal variations. Notably, over 50% of the temperature predictive ASVs identified from the two datasets belonged to the family Vibrionaceae. Together, our results identify temperature as a robust predictor of community-level variation and highlight specific microbial taxa putatively involved in the response to thermal environment.

Korthalsia (Blume) is a genus in the sub-family Calamoideae of the family Arecaceae. Research on a phenetic study of Korthalsia in Sumatra has never been published. The research was conducted to describe the specific characteristics of Korthalsia spp. in Sumatra and analyze their morphological character and similarity with a phenetic analysis. There were 85 herbarium specimens of Korthalsia deposited at the Herbarium Bogoriense (BO). Twenty-four vegetative and six generative characters were observed. Scoring was analyzed with a multinomial approach. The analysis was performed using the NTSys pc 2.02. The result showed that nine species of Korthalsia in Sumatra were distinguished based on their ocrea types, leaflets shape, and rachillae. The phenogram showed a similarity coefficient value of 0.53 for two main clusters, cluster A consisting of 4 species of Korthalsia (K. debilis, K. paucijuga, K. rigida, and K. rostrata) and Cluster B consisting of 5 species (K. echinometra, K. flagellaris, K. laciniosa, K. hispida, and K. robusta).

Background: Burns is a form of tissue damage caused by high temperatures. Echinometra matthaei sea urchins have several secondary metabolites that can potentially help in the healing process of burns. In this study, 70% E. matthaei ethanol extract was formulated in the form of O / W (oil in water) type cream preparations which were applied topically. Objective: This study aims to determine the effectiveness of E. matthaei ethanol extract cream preparations on the healing of second-degree burns in Wistar strain rats. In this study preparations were made in 3 formulations, namely Formulation 1 (extract concentration of 1%), Formulation 2 (extract concentration of 3%), and Formulation 3 (extract concentration of 5%). This research was conducted for 7 days with the method used is the post-test only control group design. Experiments were given induction of burns using a hot plate with a diameter of 20 mm at a temperature of ± 200ºC for 15 seconds. Wound healing is observed periodically by observing macroscopically healing inflammation of the inflammatory phase and observing tissue growth in the proliferation phase. Results: The average percentage of inflammation healing showed improvement in the F2: 100%, F1: 80%, F3: 71% results were better than the wound group: 50% as evidenced by the value α = 0.012 (

Relationships between animals and their associated microbiota are dependent on both the evolutionary history of the host and on the environment. The majority of studies tend to focus on either one of these factors but rarely consider how both determine the community composition of the associated microbiota. One ‘natural experiment’ to test how evolutionary history, shared environments, and the interaction between these factors drive community composition is to compare geminate species pairs. Echinoids separated by the Isthmus of Panama are suitable for this comparison due to their known evolutionary history and differences in the oceanographic characteristics of the Caribbean Sea and the Pacific Ocean. By comparing the bacterial communities of the eggs of Echinometra and Diadema geminate species pairs, we show that each pair of geminate species associates with a distinct bacterial community in a pattern consistent with phylosymbiosis, and that the interaction between the evolutionary history of the host and the environment best explains differences in these communities. Moreover, we found that the relative abundance of particular bacterial taxa differed considerably between the 2 bodies of water and that the 2 Caribbean Echinometra species were dominated by unclassified bacterial taxa within the phototrophic Oxyphotobacteria. Taken together, data presented here support the hypothesis that the bacterial communities associated with geminate species are another characteristic of these species that have diverged in ~2.8 million years of isolation.

Few studies have investigated the effects of ocean warming and acidification on marine benthic organisms over ecologically relevant time scales. We used an environmentally controlled coral reef mesocosm system to assess growth and physiological responses of the sea urchin species Echinometra sp. A over 2 generations. Each mesocosm was controlled for temperature and pCO2 over 29 mo under 3 climate change scenarios (present day and predicted states in 2050 and 2100 under RCP 8.5). The system maintained treatment conditions including annual temperature cycles and a daily variation in pCO2. Over 20 mo, adult Echinometra exhibited no significant difference in size and weight among the treatments. Growth rates and respiration rates did not differ significantly among treatments. Urchins from the 2100 treatment had elevated ammonium excretion rates and reduced O2:N ratios, suggesting a change in catabolism. We detected no difference in spawning index scores or oocyte size after 20 mo in the treatments, suggesting that gonad development was not impaired by variations in pCO2 and temperature reflecting anticipated climate change scenarios. Larvae produced from experimentally exposed adults were successfully settled from all treatments and raised for 5 mo inside the mesocosm. The final size of these juveniles exhibited no significant difference among treatments. Overall, we demonstrated that the mesocosm system provided a near natural environment for this urchin species. Climate change and ocean acidification did not affect the benthic life stages investigated here. Importantly, in previous short-term (weeks to months) experiments, this species exhibited reductions in growth and gonad development, highlighting the potential for short-term experiments with non-acclimated animals to yield contrasting, possibly erroneous results.

Pantai Gunung Kidul memiliki beberapa biota laut salah satunya bulu babi (Echinodermata). Penelitian ini bertujuan mengidentifikasi jenis bulu babi di kawasan perairan pantai Gunung Kidul, Yogyakarta. Penelitian bulu babi di kawasan perairan pantai Gunung Kidul dilakukan pada bulan April sampai dengan Mei 2018 di 3 (tiga) lokasi yaitu Pantai Drini, Pantai Ngrenehan, dan Pantai Widodaren. Pengambilan data dilakukan dengan menggunakan metode transek kuadrat ukuran 1m x 1m. Dari hasil penelitian diperoleh 7 (tujuh) jenis bulu babi yang tergolong dalam 4 (empat) famili dan 3 (tiga) ordo. Jumlah jenis bulu babi yang paling banyak ditemukan di Pantai Widodaren, dengan total 6 (enam) jenis, yaitu Echinometra sp., Echinometra mathaei, Heterocentrotus sp., Tripneustes ventricosus, Colobocentrotus atratus dan Arbacia lixula. Sedangkan di Pantai Drini dan Ngrenehan ditemukan masing-masing 4 (empat) jenis yaitu Echinometra sp. Echinometra mathaei, Heterocentrotus sp.,dan Stomopneustes variolaris.

Continuous long-term monitoring is important for detecting ecological changes and understanding their causes, including anthropogenic impacts such as climate changes and eutrophication. Nonetheless, such long-term population studies have been rare, especially for sea urchins, which can affect community dynamics owing to their extensive herbivory and large population fluctuations. Here we present a long-term (from 1963 to 2014) dynamics of sea urchins in a fixed quadrat on a lower intertidal rocky flat in Hatakejima Island, southern Japan. We also conducted a complementary survey over the entire island approximately every five years from 1975 to 2013, and a 41-year assay for developmental abnormality of the sea urchin Heliocidaris crassispina using water adjacent to the island. The abundance of three commonest species in this area (H. crassispina, Echinostrephus molaris, and Echinometra spp.) and the richness of urchin species showed large variations, with high numbers in the 1960s and 1970s, followed by an abrupt decline in the late 1970s or early 1980s, and a gradual recovery subsequently. The species abundance and richness in the entire island survey showed good correlations with those in the quadrat census. Statistical analyses indicated that increasing water temperature and red tides were the major factors influencing the dynamics of abundance and species richness. Our studies reveal that anthropogenic environmental changes influence the long-term dynamics in abundance and richness of sea urchins.

De Blainville originally described two Echinometra species, E. mathaei and E. oblonga in the Indo-Pacific. Recent studies concerning gamete incompatibility, embryology, karyotype, morphology, molecular structure and ecology of Okinawan Echinometra four types have shown that at least four species are represented in what used to be called E. mathaei. Type A with white-tipped spines and spindle-shaped gonad spicules will stay E. mathaei. Type B with unicolor spines and spindle-shaped gonad spicules, newly discovered in Okinawa, will be Echinometra sp.2. Type D with black spines and tri-radiate gonad spicules may be E. oblonga. It was shown that there are disagreements among the phylogenetic trees of the four species based on morphological, embryological, cytogenetical and biochemical studies.

In the tropical sea urchin genus Echinometra, two Hawaiian species are the most closely related urchin congeners known, based on analysis of mitochondrial DNA and single copy nuclear DNA differences. These species show strong blocks to interspecific hybridization with fewer than 10% of eggs fertilized by heterologous sperm. Preliminary sequences of part of the gene for the sperm protein bindin, which is known to mediate sperm attachment and fusion in sea urchins, shows a prevalence of codon insertions or deletions between Echinometra species. Thus, bindin may evolve by a recombinatorial rather than point substitution mechanism. Because of its primary role in fertilization, small changes in bindin sequence may have a disproportionate effect on reproductive isolation. Rapid functional evolution of this protein may be associated with rapid speciation, and can be examined by further comparisons of closely related species.

Sea urchins have skeletons made of calcareous plates, and growth occurs by enlarging plates and adding new ones. Spines grow as do ossicles of Aristotle's lantern. Differences in chemical composition of ossicles correlate with growth. Ossicles have growth lines that have been used to estimate age, and various tagging methods have been developed to model growth. The methods used include physical tags, as well as chemicals that are incorporated into the skeleton and later detected to measure growth increments. A large number of growth models have been employed, including the Bertalanffy, logistic, Gompertz, Tanaka, Gaussian, logistic dose response, and inverse logistic models, and these are compared using the Akaike Information Criterion. A frequent problem with data is a lack of small and large individuals. Survival is modeled using a negative exponential and annual rates are determined using a combination of growth models and population size structure.

Four recently-diverged species of Indo-Pacific sea urchins, belonging to the genus Echinometra, occur most abundantly and sympatrically along the coast of Okinawa Island, southern Japan. Among them, the two most distinct species—Echinometra sp. A (Ea) and Echinometra mathaei (Blainville, 1825) (Em)—were examined for potential hybridization through a series of cross-fertilization and hybrid raising experiments. Compared to conspecific crosses, fertilization rates in both heterospecific crosses were very low, even at a very high concentration of sperm. At limited sperm concentration, where conspecific crosses achieved near 100% fertilization, heterospecific crosses had

Urchins are the last abundant grazers of macroalgae on most Caribbean reefs following the historical overexploitation of herbivorous fishes. The long-spined urchin Diadema antillarum was particularly effective at controlling macroalgae and facilitating coral dominance on Caribbean reefs until its ecological extinction from a catastrophic disease epidemic in the early 1980s. Despite their important role in the structure and functioning of Caribbean reef ecosystems, the natural dynamics of Caribbean reef urchin communities are poorly known due to the paucity of ecological survey data prior to large-scale human disturbances and the Diadema dieoff. To help resolve the baseline abundances and ecological roles of common urchin taxa, we track changes in urchin abundance and composition over the past 3000 yr from analysis of subfossil urchin spines preserved in reef matrix cores collected in Caribbean Panama. Echinometra consistently dominated the subfossil spine assemblage, while Diadema was consistently rare in the subfossil record in this region. Rather than increasing during a period of heightened human exploitation of their fish competitors and predators, Diadema began declining over a millennium ago. Convergent cross mapping (CCM) causality analyses reveal that Diadema abundance is causally related to coral community composition. Diadema is negatively affected by Acropora cervicornis dominance, likely due to the tight association between this coral and the threespot damselfish, an effective Diadema competitor. Conversely, Diadema positively affects the abundance of the coral Madracis mirabilis, possibly via its control of macroalgae. Causal relationships were not detected among abundances of individual urchin taxa, indicating that inter-specific echinoid competition is not a factor limiting Diadema recovery. Our detailed record of prehistorical and historical urchin community dynamics suggests that the failure of Diadema to recover over 30 yr after its mass mortality event may be due in part to the prey release of damselfish following the long-term overfishing of piscivorous fishes.

Echinometra mathaei is a species complex with its constituent reproductively-isolated species informally called A, B, C and D based on studies done in Okinawa and the Red Sea. Little research has been done on this genus, and to our knowledge no studies have been done on the E. mathaei complex in the Philippines. To help clarify species delineations in the E. mathaei complex, a comparative study was done between two localities in Western Visayas, Philippines: the Taklong Island National Marine Reserve, in Nueva Valencia, Guimaras and Barangay Unidos in Nabas, Aklan. Morphological characteristics (spine color, milled rings, and skin around the peristome) and tubefeet and gonad spicules were observed. Two or possibly three species of Echinometra were found in the two sites based on their morphology and spicules, namely: Echinometra sp. A, Echinometra sp. C, and Echinometra affinity C, which resembles sp. C but differs in the milled rings and gonad spicules. Echinometra sp. C and E. affinity C cannot be distinguished on the basis of field-visible characters, thus the two morphs are referred to as Echinometra VC for the purpose of field surveys. Echinometra VC and Echinometra sp. A exhibited differences in abundance (VC was much more common) and microhabitat (VC was restricted to rocky shores and never observed in coral communities). To study the abundance and distribution of Echinometra VC, 50 m by 2 m belt transects were surveyed along the rocky shores of both sites: two parallel transects (at 0 m and at 0.9 m) and a perpendicular transect (only in Nabas), each with three replicates. The transect data showed that the mean densities for 0 m and 0.9 m in Nabas are significantly higher in Taklong yielding p-values of 0.001 and 0.002, respectively, when analyzed using t-test.Of the two sites, only Nabas showed a significant difference between the mean densities at 0 m and 0.9 m, with the mean density at 0.9 m significantly higher than that of 0 m yielding a p-value of 0.02 when analyzed using two-sample t-test. A Poisson regression on the perpendicular transect data from Nabas showed a trend of increasing Echinometra density with increasing distance from the shore. In the future, DNA barcoding and cross-fertilization studies should be performed in order to confirm the species of Echinometra observed. Many factors can affect the density and distribution of Echinometra, so further studies must be conducted to explain observed differences in their distribution and abundance.

Erroneous— Echinometra lucunter lucunter (Linnaeus, 1758) Reports for the Azores: Echinometra subangularis Desmoulins—Agassiz 1872: 234. See: Mortensen (1943a: 357–368, figs. 172–175, pl. 41, figs. 1–5, pl. 42, figs. 12–14, pl. 43, figs. 1–13, pl. 44, fig. 9, pl. 64, figs. 17, 20–24); Pawson (1978: 20–23, figs. 8–10). Occurrence: Atlantic, from North Carolina and Bermuda, southwards to Brazil (Mortensen 1943 a, Schultz 2006), and eastwards from Cape Verde to Angola (H.L. Clark 1925, Mortensen 1936); the subspecies E. lucunter polypora is restricted to Ascension and St. Helena islands (Pawson 1978). Depth: 0–45 m (Mortensen 1943a). Habitat: hard substrates (bioeroder; Mortensen 1943a). Larval stage: planktotrophic (Mortensen 1921). Fossil record: Ericichnus bromleyi, a relatively recent described ichnospecies portraying groove-borings found in a Pliocene fossiliferous outcrop in Malbusca (Santa Maria Island) is thought to be made by the sea urchin Echinometra lucunter (see Santos et al. 2015). Commercial value: edible (Lawrence 2007). Remarks: Agassiz (1872) listed the Azores under the geographical range of Echinometra lucunter (under the name Echinometra subangularis), which is clearly a misprint. The author never mentioned the archipelago again, whether listing the examined specimens’ locations or discussing the distribution range for this species. This tropical species does not occur in the present-day shallow waters of the Azores and no specimens were ever reported from the area., Published as part of Madeira, Patrícia, Kroh, Andreas, Cordeiro, Ricardo, De, António M., Martins, Frias & Ávila, Sérgio P., 2019, The Echinoderm Fauna of the Azores (NE Atlantic Ocean), pp. 1-231 in Zootaxa 4639 (1) on page 172, DOI: 10.11646/zootaxa.4639.1, http://zenodo.org/record/3342161, {"references":["Linnaeus, C. (1758) Systema Naturae. 1. 10 th Edition. Impensis Direct. Laurentii Salvii, Holmiae, 824 pp.","Mortensen, T. (1943 a) A Monograph of the Echinoidea. III. 3. Camarodonta. II. Echinidae, Strongylocentrotidae, Parasaleniidae, Echinometridae. C. A. Reitzel, Copenhagen, 446 pp.","Pawson, D. L. (1978) The Echinoderm Fauna of Ascension Island, South Atlantic Ocean. Smithsonian Contributions to the Marine Sciences, 2, 1 - 31. https: // doi. org / 10.5479 / si. 01960768.2.1","Clark, H. L. (1925) A catalogue of the Recent sea urchins (Echinoidea) in the British Museum (Natural History). Trustees of the British Museum and Oxford University Press, London, 250 pp.","Mortensen, T. (1936) Echinoidea and Ophiuroidea. Discovery Reports, 12, 199 - 348. https: // doi. org / 10.5962 / bhl. part. 8051","Mortensen, T. (1921) Studies of the Development and Larval Forms of Echinoderms. G. E. C. Gad, Copenhagen, 294 pp. https: // doi. org / 10.5962 / bhl. title. 11376","Santos, A., Mayoral, E., Dumont, C. P., da Silva, C. M., Avila, S. P., Gudveig Baarli, B., Cach \" o, M., Johnson, M. E. & Ramalho, R. S. (2015) Role of environmental change in rock-boring echinoid trace fossils. Palaeogeography, Palaeoclimatology, Palaeoecology, 432, 1 - 14. https: // doi. org / 10.1016 / j. palaeo. 2015.04.029","Lawrence, J. M. (2007) Edible Sea Urchins: Biology and Ecology. Elsevier, Boston, 380 pp.","Agassiz, A. (1872 - 1874) Revision of the Echini. Illustrated catalogue of the Museum of Comparative Zo ˆ logy at Harvard College, 7 (1 - 4), 1 - 762."]}

In species with complex life cycles, early developmental stages are often less thermally tolerant than adults, suggesting that they are key to predicting organismal response to environmental warming. Here we document the optimal and lethal temperatures of larval sea urchins, and we use those to calculate the warming tolerance and the thermal safety margin of early larval stages of seven tropical species. Larvae of Echinometra viridis, Echinometra lucunter, Lytechinus williamsi, Eucidaris tribuloides, Tripneustes ventricosus, Clypeaster rosaceus, and Clypeaster subdepressus were reared at 26, 28, 30, 32, and 34 °C for 6 days. The temperatures at which statistically significant reductions in larval performance are evident are generally the same temperatures at which statistically significant reductions in larval survival were detected, showing that the optimal temperature is very close to the lethal temperature. The two Echinometra species had significantly higher thermal tolerance than the other species, with some surviving culture temperatures of 34 °C and showing minimal impacts on growth and survival at 32 °C. In the other species, larval growth and survival were depressed at and above 30 or 32 °C. Overall, these larvae have lower warming tolerances (1 to 5 °C) and smaller thermal safety margins (-3 to 3 °C) than adults. Survival differences among treatments were evident by the first sampling on day 2, and survival at the highest temperatures increased when embryos were exposed to warming after spending the first 24 hours at ambient temperature. This suggests that the first days of development are more sensitive to thermal stress than are later larval stages.

Echinometra ex grupo mathaei (Blainville, 1825) Material studied. WUSL /ER/225 (dry, denuded) from Hiriketiya, WUSL /ER/226 (dry, denuded) from Hikkaduwa; WUSL /ER/227 (wet, with spines) from Beruwala. Literature records for Sri Lanka. Clark (1915, 1925), Price & Rowe (1996), Fernando (2006), Jayakody (2012), Gayashan & Jayakody (2012). Distribution in Sri Lanka. Southern and western coasts of Sri Lanka. Recorded depth range in Sri Lanka. 0.5– 1 m (present study), 0.5– 5 m (previous records). Habitat. Rocky shores, in rock crevices, among rock boulders, channels, and self-made burrows. Observed occurrence in this study. Southern coast (Hiriketiya and Hikkaduwa) and the western coast (Beruwala) of Sri Lanka. Remarks. E. mathaei can be distinguished from the other Sri Lankan echinometrids, except from E. oblonga, in having the test elongated through the axis between ambulacrum I and interambulacrum 3, and only four pore pairs in the pore arcs of the ambulacra. E. mathaei and E. oblonga cannot be easily distinguished from each other. Mortensen (1943b: 394) admits that “there are no reliable characters in the test distinguishing oblonga from the typical mathaei ”. Hence, molecular analyses are required to distinguish these species unequivocally, although sperm morphology and spicules have been shown to be very useful in distinguishing some members of the E. mathaei species complex (Arakaki et al. 1998; Bronstein & Loya 2013). Two colour variants, green and brown, occur in Sri Lanka. There is a high likelihood that more than one species is present on the island, pending full molecular analyses of additional specimens from across the range of echinometrids currently listed under the names E. mathaei and E. oblonga.

Echinometra lucunter (Linnaeus, 1758) Figures 6 A–M, 18 C, 19 B Echinus lucunter Linnaeus, 1758: 665. Echinometra sublangularis A. Agassiz, 1872: 72 –74.– Rathbun, 1879: 143. Echinometra lucunter Gray, 1825: 427.– Krau, 1950: 358.– Bernasconi, 1955: 62 –63, pl. 2, figs 1, 5.– Tommasi, 1957: 21, 29, figs 16, 20, pl. 1, fig. 1–2; 1959: 602, 603; 1966a: 16–17.– Brito, 1960b: 4, fig. 1e; 1962: 5; 1968: 21–22, pl. 10, figs 2–3; 1971: 263.– Lima-Verde, 1969: 10.– Tommasi & Aron, 1987: 3.– Castro et al., 1995: 476.– Alves & Cerqueira, 2000: 547.– Fernandes et al., 2002: 422.– Attrill et al., 2004: 154.– Magalhães et al., 2005: 63.– Netto et al., 2005: 214.– Martins & Martins de Queiroz, 2006: 209. – Ventura et al., 2007b: 279, tab.11.2, 280, fig. 11.1b, 290, anexo 11.1.– Gondim et al., 2008: 155; 2011: 81; 2014a: 99.– Oliveira et al., 2010: 10.– Xavier, 2010: 75.– Martins et al., 2012a: 55.– Miranda et al., 2012: 142, fig. 4c.– Ventura et al., 2014: 65, fig.– Martins et al., 2018: 529, figs 6–7. Echinometra lucunter lucunter Hendler et al., 1995: 222 –225. Material examined. Rio Grande do Norte: 4 spms, Ponta de Cajaúna, Tibau do Sul, 19.VIII.1982 [UFPB/ ECH.22]; 11 spms, Pipa Beach, Tibau do Sul, 19.VIII.1982 [UFPB/ECH.25]; 7 spms, Barra de Maxaramguape, Ceará-Mirim, 21.VIII.1982 [UFPB/ECH.26]; 4 spms, Cabo do Cabopari, Baía Formosa, 18.VIII.1982 [UFPB/ ECH.27]; 1 spm, Cabo de São Roque, 22.VIII.1982 [UFPB/ECH.1611]; 2 spms, Pirangi do Sul, Nísia Floresta, 22.VIII.1982 [UFPB/ECH.1642]; 3 spms, Zumbi Beach, Rio do Fogo, 3–6 m, 27.XI.2009 [MZUSP, without voucher]; 2 spms, 5°19,908′S 35°21,607′ W, Zumbi Beach, 27.XI.2009 [MZUSP, without voucher]. Paraíba: 2 spms, Ponta do Seixas, João Pessoa, 8.V.1977 [UFPB/ECH.01]; 3 spms, Cabo Branco Beach, João Pessoa, 12.V.1980 [UFPB/ECH.02]; 2 spms, Ponta do Seixas, João Pessoa, 12.II.1982 [UFPB/ECH.03]; 3 spms, Cabo Branco Beach, 03.VII.1985 [UFPB/ECH.21]; 5 spms, Cabo Branco Beach, 12.III.1981 [UFPB/ECH.351]; 1 spm, Ponta de Campina, Cabedelo, 24.VIII.2006 [UFPB/ECH.352]; 3 spms, Cabo Branco Beach, 04.XI.2006 [UFPB/ ECH.354]; 1 spm, Cabo Branco Beach, 09.IX.2006 [UFPB/ECH.355]; 1 spm, 6°55'S 34°47′W, 10 m, 03.VII.2006 [UFPB/ECH.573]; 1 spm, Cabo Branco Beach, 26.IX.2007 [UFPB/ECH.702]; 5 spms, Coqueirinho Beach, Conde, 27.X.2007 [UFPB/ECH.777]; 2 spms, Seixas Reef, 22.XII.2007 [UFPB/ECH.1018]; 4 spms, Baía da Traição Beach, 24.XI.2007 [UFPB/ECH.1020]; 1 spms, Barra de Camaratuba Beach, Mataraca, 23.I.2008 [UFPB/ ECH.1146]; 2 spms, Areia Vermelha Reef, Cabedelo, 22. II.2008 [UFPB/ECH.1148]; 2 spms, Baía da Traição Beach, 04.V.2008 [UFPB/ECH.1181]; 2 spms, Barra de Camaratuba Beach, Mataraca, 06.V.2008 [UFPB/ ECH.1182]; 3 spms, Areia Vermelha Reef, Cabedelo, 06.IV.2008 [UFPB/ECH.1212]; 1 spm, Cabo Branco Beach, 28.X.2007 [UFPB/ECH.1315]; 5 spms, Cabo Branco Beach, 16.XII.1997 [UFPB/ECH.1317]; 3 spms, Cabo Branco Beach, 25.X.2007 [UFPB/ECH.1319]; 2 spms, Cabo Branco Beach, 21.III.2000 [UFPB/ECH.1320]; 2 spms, Ponta do Seixas, 25.V.1998 UFPB/ECH.1322]; 4 spms, Cabo Branco Beach, 07.VI.2001 [UFPB/ ECH.1323]; 3 spms, Santa Catarina Beach, Cabedelo, 18.V.2007 [UFPB/ECH.1324]; 3 spms, Tambaba Beach, Conde, 28.IX.2007 [UFPB/ECH.1325]; 12 spms, Cabo Branco Beach, 0 9.III.2005 [UFPB/ECH.1326]; 1 spm., Cabo Branco Beach, 25.X.2007 [UFPB/ECH.1328]; 3 spms, Ponta do Seixas, João Pessoa, 03.XI.1982 [UFPB/ ECH.1329]; 2 spms, Cabo Branco Beach, 19.IX.2005 [UFPB/ECH.1331]; 3 spms, Cabo Branco Beach, 09.II.2001 [UFPB/ECH.1335]; 18 spms, Cabo Branco Beach, 01.XII.1975 [UFPB/ECH.1336]; 9 spms, Galé Reef, Pitimbú, 12.XII.2008 [UFPB/ECH.1455]; 2 spms, Barra de Mamanguape Reef, Rio Tinto, 10.I.2009 [UFPB/ECH.1456]; 2 spms, Areia Vermelha Reef, Cabedelo, 06.IV.2008 [UFPB/ECH.1472]; 3 spms, Cabo Branco Beach, 13.XI.2008 [UFPB/ECH.1473]; 1 spm, Pier de Cabedelo, Cabedelo, 05.V.2008 [UFPB/ECH.1476]; 5 spms, Seixas Reef, João Pessoa, 12.I.2009 [UFPB/ECH.1477]; 2 spms, Maceiozinho Beach, Jacumã, 06.V.2008 [UFPB/ECH.1482]; 2 spms, Tabatinga Beach, Conde, 10.II.2009 [UFPB/ECH.1512]; 3 spms, Coqueirinho Beach, Conde, 03.VI.2008 [UFPB/ECH.1513]; 1 spm, Tambaba, Beach Conde, 10.II.2009 [UFPB/ECH.1514]; 2 spms, Barra de Mamanguape Reef, Rio Tinto, 11.II.2009 [UFPB/ECH.1515]; 1 spm, Cabo Branco Beach, 03.XI.1982 [UFPB/ ECH.1649]; 1 spm, Pitimbú Reef, Pitimbú, 16.IX.2006 [UFPB/ECH.1656]; 2 spms, Pitimbú Reefs, Pitumbú, 16.IX.2005 [UFPB/ECH.1675]; 1 spm, Cabo Branco Beach, 16.III.2002 [UFPB/ECH.1701]; 1 spm, Cabo Branco Beach, 29.V.2009 [UFPB/ECH.1702]; 1 spm, Cabo Branco Beach, 09.IV.2005 [UFPB/ECH.1729]; 2 spms, Tambaba Beach, Conde, 04.VI.2008 [UFPB/ECH.1730]. Pernambuco: 13 spms, rocky shore between the Gabu Beach and Cabo de Santo Agostinho, 04.IX.1982 [UFPB/ECH.04]; 6 spms, Itarema Beach, Cabo, 03.IX.1982 [UFPB/ECH.05]; 6 spms, Ponta de Pedras, 30.X.1982 [UFPB/ECH.11]; 3 spms, Candeias Reef, Jaboatão, 02.XI.1982 [UFPB/ECH.12]; 1 spm, Piedade Reef, Jaboatão, 2.XI.1982 [UFPB/ECH.13]; 3 spms, Gabu Reef, Cabo, 03.IX.1982 [UFPB/ECH.29]; 1 spm, São José da Coroa Grande, 06.IX.1982 [UFPB/ECH.1316]; 5 spms, Pau Amarelo Reef, Paulista, 01.XI.1982 [UFPB/ECH.1327]; 1 spm, Catuama, Goiana, 31.X.1982 [UFPB/ ECH.1332]; 2 spms, Gamela Sirinhaén, 05.IX.1982 [UFPB/ECH.1659]; 1 spm, Ponta de Serrambi Beach, Ipojuca, 05.IX.1982 [UFPB/ECH.1670]. Alagoas: 1 spm, Pajuçara Beach, Maceió, 21.IX.1982 [UFPB/ECH.06]; 3 spms, Francês Beach, Marechal Deodoro, 19.X.1982 [UFPB/ECH.10]; 3 spms, Riacho Doce Beach, 31.I.1983 [UFPB/ ECH.16]; 3 spms, Ponta Verde Beach, Maceió, 20.X.1982 [UFPB/ECH.28]; 1 spm, Ponta Verde Beach, 31.I.1983 [UFPB/ECH.1330]; 1 spm, Paripueira Beach, 01.II.1983 [UFPB/ECH.1653]; 2 spms, Francês Beach, Marechal Deodoro, 29.I.1983 [UFPB/ECH.1655]; 1 spm, Pontal do Cururipe, Curuipe, 26.I.1983 [UFPB/ECH.1733]; 1 spm., Saco da Pedra Reef, Maceió, 10.II.2009 [UFSITAB-206]; 1 spm, Saco da Pedra Reef, 10.II.2009 [UFSITAB- 208]; 1 spm, Saco da Pedra Reef, 10.II.2009 [UFSITAB-250]. Bahia: 4 spms, Ponta da Coroa Vermelha, Santa Cruz da Cabrália, 15.X.1982 [UFPB/ECH.08]; 1 spm, Ponta Grande Reef, Porto Seguro, 15.X.1982 [UFPB/ ECH.09]; 2 spms, South of the Redonda Island, Abrolhos, 01.II.1982 [UFPB/ECH.15]; 5 spms, Ponta de Imbaçuaba, Cumuruxatiba, 13.X.1982 [UFPB/ECH.23]; 1 spm, reef between Cumuruxatiba and Ponta de Ibaçuaba, Prado, 28.IX.1982 [UFPB/ECH.30]; 4 spms, south-west of Siriba Islands, Abrolhos, 30.XI.1982 [UFPB/ ECH.31]; 4 spms, Imbaçuaba Beach, Prado, 14.X.1982 [UFPB/ECH.33]; 1 spm, Pituba Beach, Salvador, 17.IX.1982 [UFPB/ECH.1318]; 1 spm, Pitanga Beach, Lauro Freitas, 16.IX.1982 [UFPB/ECH.1333]; 1 spm, Coroa Beach, Itaparica, 18.IX.1982 [UFPB/ECH.1334]; 1 spm, Pituba Beach, Salvador, 17.IX.1982 [UFPB/ ECH.1634]; 1 spm, Penha Beach, Vera Cruz, Itaparica, 08.IX.1982 [UFPB/ECH.1654]; 3 spms, Arembepe Beach, Camaçari, 16.IX.1982 [UFPB/ECH.1658]; 1 spm, Itaparica Beach, 22.XII.1984 [UFPB/ECH.1674]. Description. Test elliptical, oral surface concave (TD = 5.8 to 129 mm; TH = 2.5 to 45.5 mm) (Fig. 6A, B, I, J). Apical system hemicyclic (Fig. 6K). Plates of periproct and apical system densely covered by small spines (Fig. 6K). Ocular and genital plates with many tubercles of various sizes (Fig. 6K). Ambulacral plate polygeminate (echinoid type), with six pairs of pores arranged in arc, one primary tubercle and few secondary tubercles (Fig. 6L). Interambulacral plate with one primary tubercle and many secondary tubercles (Fig. 6M). Primary and secondary tubercles of ambulacra and interambulacra non-crenulate and non-perforate (Fig. 6I, L, M). Primary spines of variable length, thick at base and thin at tip (Fig. 6A). Secondary spines thin and short. Peristome large, with few buccal plates densely covered by purple ophicephalous pedicellariae (Fig. 6B). Tube feet with C-shaped spicules and ossicles forming rosette in terminal discs (Fig. 6G, H). Spicules of tube feet often organized into longitudinal rows. Pedicellariae. Globiferous, ophicephalous, tridentate and triphyllous pedicellariae present over entire test. Globiferous pedicellariae of various sizes, with a long stalk, without a neck, and with three pairs of well-developed venom glands, in which C-shaped spicules are found. Valves with lateral tooth paired or unpaired and a single end tooth (Fig. 6C, D). Ophicephalous pedicellariae with a long stalk and short neck. Valves with small marginal teeth that are serrate (like shark teeth) (Fig. 6E). Tridentate pedicellariae short, with stalk and neck long, in which Cshaped spicules similar to those of the tube feet are found. Valves narrow, long, with margins slightly serrate (Fig. 6F). Triphyllous pedicellariae with a long neck, about the same length as stalk. Valves short and broad, being narrower at the base and widening towards the tip. Colour. Echinometra lucunter can be black, gray, green, red, or even bluish, displaying a high degree of colour polymorphism (Lessios 1998). The spines are black but may have a greenish tinge at the base and a purple tinge at the apex. Naked test white. Distribution. Mexico, Cuba, Belize, Guatemala, Honduras, Nicaragua, Jamaica, Haiti, Dominican Republic, Caribbean Sea, Costa Rica, Panama, Puerto Rico, Madagascar, Mozambique, Colombia, Venezuela, and Brazil (del Valle García et al. 2008; Alvarado et al. 2008; Kroh & Mooi 2016). In Brazil from CE, PB, PE, AL, BA, ES, RJ, SP, SC, including Abrolhos, Fernando, Fernando de Noronha, Trindade and Martin Vaz Islands (Rathbun 1879; H.L. Clark 1925; Brito 1962, 1968; Tommasi 1966a; Lima-Verde 1969; Fernandes et al. 2002; Magalhães et al. 2005; Gondim et al. 2008, Lima & Fernandes 2009; Xavier 2010; Miranda et al. 2012; Martins et al. 2018). Herein we first record the species for the State of Rio Grande do Norte. The species is known to occur between 0 and 45 m (Hendler et al. 1995), but it is almost exclusively a shallow-water species, restricted to less than 1 m of depth (Lessios 1998). Remarks. Presently eight species of Echinometra are known worldwide (Bronstein & Loya 2013), two of which occur in the tropical part of the Western Atlantic [E. lucunter and E. viridis A. Agassiz, 1863]. Only E. lucunter occurs along the Brazilian coastline. Echinometra lucunter differs from E. viridis in not having ambulacral plates with five pairs of pores and a reddish brown test with yellowish spines. In this study, we observed small morphological differences among adults and young individuals, such as the dicyclic apical system with few tubercles in young individuals and hemicyclic with many tubercles in adults. The length and thickness of spines were also quite variable, from long and thin to short, thick, and blunt. Apparently, these variations were not related to environment (low or high energy habitats) nor to developmental stage, but further studies are necessary to confirm this observation. Young specimens tend to have spines that are thin and long. Lewis & Storey (1984) observed that individuals living in high energy habitats tend to have thicker, smaller, and more flattened tests than specimens from low energy habitats. Ecological notes. This species inhabits the intertidal and subtidal zones of reef environments but is common in the surf zone, where it lives inside crevices excavated by the action of their spines and teeth on the rock substrate (Hendler et al. 1995) (Fig. 19B). According to Espinoza et al. (2008), this species can be also be found in sandy substrates and banks of seagrass (e.g., Thalassia testudinum K.D. Koenig, 1805). Echinometra lucunter is nocturnal and lives almost permanently inside of its burrow. Only a few individuals leave their burrows at night to feed. The species feeds primarily on drifting algae (McPherson 1969), but may also prey on marine invertebrates such as sponges and cnidarians (McClintock et al. 1982; McClanahan & Muthiga 2007). Echinometra is considered a "gardener" species, feeding on the algae that grow inside of its burrow, moving back and forth along the burrow to allow algae to regenerate as it feeds on new growth (McClanahan & Muthiga 2007; Mooi, personal communication). Griinbaum et al. (1978) reported an agonistic behaviour in individuals of this species. During our field surveys, we observed some specimens of E. lucunter exhibiting "covering behaviour". Echinometra lucunter is the most common species in the intertidal zone of the NE coast of Brazil, forming high-density populations in these areas (Fig. 19B). Due to its habit of excavating rocks and forming dense populations, this species plays an important role in the bioerosion of reef environments (Hendler et al. 1995) (Fig. 20B). Echinometra lucunter, as a specialized herbivore, also has an important role in the reef food web, where it acts in controlling macroalgal cover. It is also the most important prey of the gastropod Cassis tuberosa (Linnaeus, 1758) throughout the Western Atlantic (Dias et al. 2017). According to Martins et al. (2012a), E. lucunter was among the sea urchin species captured for the aquarium trade on the coast of Salvador (BA). In Cabo de Santo Agostinho (PE), there is a traditional event called "Festa da Ouriçada" (Sea Urchin Festival), which occurs every December 13 th since 1960, in devotion to Saint Luzia. 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Bulletin of Marine Science, 32, 365 - 369. Available from: http: // www. ingentaconnect. com / content / umrsmas / bullmar / 1982 / 00000032 / 00000001 / art 00030 (accessed 2 August 2013)","McClanahan, T. R. & Muthiga N. A. (2007) Ecology of Echinometra. In: Lawrence, J. M. (Ed.), Edible Sea Urchins: Biology and Ecology. Elsevier, Amsterdam, pp. 297 - 317. https: // doi. org / 10.1016 / S 0167 - 9309 (07) 80079 - 2","Griinbaum, H., Bergman, G., Abbott, D. P. & Ogden, J. C. (1978) Intraspecific agonistic behavior in the rock-boring sea urchin Echinometra lucunter (L.) (Echinodermata: Echinoidea). Bulletin of Marine Science, 28 (1), 181 - 188.","Dias, T. L. P., Mota, E. L. S., Duarte, R. C. S. & Alves, R. R. N. (2017) What do we know about Cassis tuberosa (Mollusca: Cassidae), a heavily exploited marine gastropod? Ethnobiology and Conservation, 6, 16. https: // doi. org / 10.15451 / ec 2017 - 08 - 6.16 - 1 - 13","Santos, J. O. & Andrade, M. O. (2013) Festa da Ouricada e devocao a Santa Luiza na praia de Suape-PE: expressao sincretica e simbolica da biodiversidade e do territorio de pescadores artesanais. Horizonte, 11 (30), 545 - 571. https: // doi. org / 10.5752 / P. 2175 - 5841.2013 v 11 n 30 p 545"]}

Rising atmospheric CO2 concentrations will significantly reduce ocean pH during the 21st century (ocean acidification, OA). This may hamper calcification in marine organisms such as corals and echinoderms, as shown in many laboratory-based experiments. Sea urchins are considered highly vulnerable to OA. We studied an Echinometra species on natural volcanic CO2 vents in Papua New Guinea, where they are CO2 -acclimatized and also subjected to secondary ecological changes from elevated CO2 . Near the vent site, the urchins experienced large daily variations in pH (>1 unit) and pCO2 (>2000 ppm) and average pH values (pHT 7.73) much below those expected under the most pessimistic future emission scenarios. Growth was measured over a 17-month period using tetracycline tagging of the calcareous feeding lanterns. Average-sized urchins grew more than twice as fast at the vent compared with those at an adjacent control site and assumed larger sizes at the vent compared to the control site and two other sites at another reef near-by. A small reduction in gonad weight was detected at the vents, but no differences in mortality, respiration, or degree of test calcification were detected between urchins from vent and control populations. Thus, urchins did not only persist but actually 'thrived' under extreme CO2 conditions. We suggest an ecological basis for this response: Increased algal productivity under increased pCO2 provided more food at the vent, resulting in higher growth rates. The wider implication of our observation is that laboratory studies on non-acclimatized specimens, which typically do not consider ecological changes, can lead to erroneous conclusions on responses to global change.

Two species of Echinometra are found on tropical western Atlantic reefs. E. viridis and E. lucunter. Both are grazers and bioeroders, and on some disturbed reefs E. viridis has become the dominant herbivore, particularly since the disease-caused decline of the much larger echinoid Diadema antillarum. Thus, it is critical to understand factors affecting herbivory by Echinometra, including foraging behaviors and distances, diel and lunar cycles of foraging, and densities of Echinometra, particularly E. viridis, across habitats and locations. Twenty-four hour tracking studies undertaken in the San Blas Islands of Panama, conducted at different times in the lunar cycle, revealed that on new moons both species of Echinometra primarily moved and fed at night, but the pattern reversed on full moons. These data suggest that vulnerability to predators and/or aggression by damselfishes during the night on full moons may be a significant selective force affecting diel foraging behavior. Daily distances moved (minimum estimate) averaged 19 cm for E. viridis and 11 cm for E. lucunter. The average foraging range for E. viridis was estimated to be 0.3–5% the size of that of D. antillarum, while per capita daily algal consumption by E. viridis is 20% that of D. antillarum.These results suggest more intense, localized grazing by E. viridis compared to D. antillarum. A review of published densities of E. viridis show that 50% of studied sites (location/habitat combination) have densities less than 5 m−2, a level unlikely to produce a strong herbivory effect. Densities greater than 15 m−2 were found at 25% of sites, including the San Blas Islands, Panama patch reefs in this study, which averaged 26 m−2. Where high densities are combined with low predator numbers due to fishing, E. viridis can have strong direct effects on algal assemblages, with potential indirect effects on corals and other benthic invertebrates. However, available published data indicate E. viridis has strong regional variation in abundance, as yet unexplained, that limits its potential Caribbean-wide role as a reef herbivore. Morphological traits of E. viridis that are likely related to vulnerability to predation varied across habitats. A newly-described melanic color morph comprised 4–16% of the population, with significant variation in frequency across habitat types. Body sizes (test diameter) also varied among habitats, with larger individuals much more common in habitats with fewer shelter sites. Similarly, in habitats offering less protection from predators, spine lengths were longer relative to test diameter. Morphological traits that reduce predator detection or vulnerability to predation, as well as the refuges afforded by habitat, will ultimately affect both the number of E. viridis on a particular reef and their ability to forage in the presence of predators.

* Echinometra oblonga (Blainville, 1825) Fig. 48 A–B. Echinometra oblonga: A. Agassiz, 1863: 21; A. Agassiz, 1872 –1874: 116, 433. Pl. XXXVI, Fig. 5; H.L. Clark, 1912: 373 –374; H.L. Clark, 1925a: 144; Schultz, 2011: 1276, Fig. 2275; Filander & Griffiths, 2014: 53. Pl. II, Fig. C. Echinometra mathei oblonga: Mortensen, 1943: 393 –395. Pl. XLVIII, Figs 1–20. Material examined. None, entry based on literature. Identification. Closely related to Echinometra mathaei, difficult to distinguish the two with just morphological characters. Global maximum size. Maximum test diameter 90 mm. Global distribution. East coast region of South Africa (Filander & Griffiths 2014). East Africa, Mauritius and Maldives through to Philippines, Indonesia and New Guinea to Okinawa, Guam and Hawaii, plus south Pacific Islands; strictly littoral (Schultz 2011). Remarks. Previously recognized as a morph of E. mathaei (Mortensen 1943); however subsequent genetic (Palumbi and Metz 1991, Landry et al. 2003), reproductive (Rahman & Uehara 2004) and ecological (Nishihira et al. 1991) studies led to recognition of the two as separate species (Kroh & Mooi 2015). Maher (2011) documents E. oblonga in South African waters for the first time., Published as part of Filander, Zoleka & Griffiths, Charles, 2017, Illustrated guide to the echinoid (Echinodermata: Echinoidea) fauna of South Africa, pp. 1-72 in Zootaxa 4296 (1) on pages 44-45, DOI: 10.11646/zootaxa.4296.1.1, http://zenodo.org/record/843325, {"references":["Blainville, H. M. D. (1825) Oursin, Echinus (Actinozoaires.). In: Levrault, F. G. (Eds.), Dictionnaire des Sciences Naturelles. F. G. Levrault & Le Normant, Strasbourg & Paris, pp. 59 - 98.","Agassiz, A. (1863) List of the echinoderms sent to different institutions in exchange for other specimens, with annotations. Bulletin of the Museum of Comparative Zoology at Harvard College, 1, 253 - 308.","Agassiz, A. (1872) Revision of the Echini. Memoirs of the Museum of Comparative Zoology at Harvard College, 3, 1 - 378.","Clark, H. L. (1912) Hawaiian and other Pacific Echini. The Pedinidae, Phymosomatidae, Stomopneustidae, and Echinometridae.","Clark, H. L. (1925 a) A Catalogue of the Recent Sea-urchins (Echinoidea) in the Collection of the British Museum (Natural History). Trustees of the British Museum, London, 250 pp.","Schultz, H. (2011) Sea-Urchins III, Worldwide Regular Deep Water Species. 1 st Edition. Scientific Publications, Hemdingen, 1338 pp.","Filander, Z. & Griffiths, C. L. (2014) Additions to and revision of the South African echinoid fauna (Echinodermata: Echinoidea). African Natural History, 10, 47 - 56.","Mortensen, T. (1943 a). A Monograph of the Echinoidea. III. 2. Camarodonta. I. Orthopsidae, Glyphocyphidae, Temnopleuridae and Toxopneustidae. C. A. Reitzel, Copenhagen, 553 pp.","Palumbi, S. R. & Metz, E. C. (1991) Strong reproductive isolation between closely related tropical sea urchins (genus Echinometra). Molecular Biology and Evolution, 8 (2), 227 - 239.","Landry, C., Geyer, L., Arakaki, Y., Uehara, T. & Palumbi, S. R. (2003) Recent speciation in the Indo - West Pacific: rapid evolution of gamete recognition and sperm morphology in cryptic species of sea urchin. Proceedings of the Royal Society of London, Series B: Biological Sciences, 270 (1526), 1839 - 1847. https: // doi. org / 10.1098 / rspb. 2003.2395","Rahman, M. A. & Uehara, T. (2004) Interspecific hybridization and backcrosses between two sibling species of Pacific sea urchins (genus Echinometra) on Okinawan intertidal reefs. Zoological Studies-Taipei, 43 (1), 93 - 111.","Nishihira, M., Sato, Y., Arakaki, Y. & Tsuchiya, M. (1991) Ecological distribution and habitat preference of four types of the sea urchin Echinometra mathaei on the Okinawan coral reefs. In: Yanagisawa, T., Yasumasu, I., Oguro, C., Suzuki, N. & Motokawa, T. (Eds.), Biology of Echinodermata. Balkema, Rotterdam, pp. 91 - 104.","Kroh, A. & Mooi, R. (2015) World Echinoidea Database. Available from: http: // www. marinespecies. org / echinoidea (accessed 11 April 2015)","Maher, J., (2011) The phylogeographic population structure of the oval urchin, Echinometra mathaei in KwaZulu-Natal. Unpublished Master thesis. University of KwaZulu-Natal."]}

Echinometra mathaei (Blainville, 1825) Fig. 47 A–B. Echinometra mathei: Döderlein, 1910: 248; H.L. Clark, 1912: 372; H.L. Clark, 1923: 390 –391; Mortensen, 1943: 381 –393. Pl. XLII, Figs 1–10. Pl. XLVII, Figs 1–4. Pl. LXV, Figs 16–26; Clark & Courtman-Stock, 1976: 239; Coleman et al., 1991: 170; Richmond, 1997: 298; Samyn, 2003: 204, Figs 3 E, E’; Branch et al., 2010: 234, Fig. 105.2; Schultz, 2010: 214, Figs 401–405. Material examined. MBC-A 022263; MBC-A 022657; MBC-A023311; MBC-A077879; MBC-A077878; MBC- A077880; MBC-A077881; MBC-A077876; MBC-A077877; SAMC- 22262, Identification. Test strongly elongated, rarely somewhat circular; spines stout, with white basal flange (milled ring). Distinguished by color, cleaned test white, with faint light purple tint; spines vary in color, from white to brown, sometimes greenish or purplish, often tips and milled ring white. Global maximum size. Maximum test diameter 90 mm. Global distribution. Suez to East coast region of South Africa, from Japan to Australia, and from Hawaii to South Sea Islands; from littoral to 30 m (Schultz 2010). Remarks. Inhabits holes and tunnels amongst coral blocks, known to be a rock borer (Mortensen 1943; Asgaard & Bromley 2008)). Feeds on algae and encrusting organisms, especially sponges (Mortensen 1943; Schultz 2010). Maher (2011) indicates that there is no genetic divergence amongst the color morphs in E. mathaei populations and suggests variation may be attributed to environmental parameters. However, the observed intraspecific variation may suggest a slow speciation process (Rahman & Uehara 2004)., Published as part of Filander, Zoleka & Griffiths, Charles, 2017, Illustrated guide to the echinoid (Echinodermata: Echinoidea) fauna of South Africa, pp. 1-72 in Zootaxa 4296 (1) on pages 43-44, DOI: 10.11646/zootaxa.4296.1.1, http://zenodo.org/record/843325, {"references":["Blainville, H. M. D. (1825) Oursin, Echinus (Actinozoaires.). In: Levrault, F. G. (Eds.), Dictionnaire des Sciences Naturelles. F. G. Levrault & Le Normant, Strasbourg & Paris, pp. 59 - 98.","Doderlein, L. (1910) Asteroidea, Ophiuroidea, Echinoidea. In: Schultze, L. (Ed.), Zoologische und Anthropologische Ergebnisse einer Forschungsreise im westlichen und zentralen Sudafrika ausgefuhrt 1903 - 1905 (Jenaer Denkschrift 16), 4 (1), pp. 246 - 258.","Clark, H. L. (1912) Hawaiian and other Pacific Echini. The Pedinidae, Phymosomatidae, Stomopneustidae, and Echinometridae.","Clark, H. L. (1923) The echinoderm fauna of South Africa. Annals of the South African Museum, 13 (7), 221 - 435.","Mortensen, T. (1943 a). A Monograph of the Echinoidea. III. 2. Camarodonta. I. Orthopsidae, Glyphocyphidae, Temnopleuridae and Toxopneustidae. C. A. Reitzel, Copenhagen, 553 pp.","Clark, A. & Courtman-Stock, J. (1976) The Echinoderms of Southern Africa. Publication no. 766. British Museum of Natural History, London, 277 pp.","Coleman, N., Bennett, I., Campbell, A. & Hadfield, M. (1991) Encyclopedia of Marine Animals. Blandford, London, 324 pp.","Richmond, M. D. (1997) A Guide to the Seashores of Eastern Africa and the Western Indian Ocean Islands. Swedish International Development Cooperation Agency (SIDA) and University of Dar es Salaam, Dar es Salaam, 448 pp.","Branch, G. M., Griffiths, C. L., Branch, M. L. & Beckley, L. (2010) Two Oceans: a Guide to the Marine Life of southern Africa. Struik Nature, Cape Town, 456 pp.","Schultz, H. (2010) Sea-Urchins, a Guide to Worldwide Shallow Water Species. 3 rd Edition. Scientific Publication, Hemdingen, 484 pp.","Asgaard, U. & Bromley, R. G. (2008) Echinometrid sea urchins, their trophic styles and corresponding bioerosion. In: Wisshak, M. & Tapanila, L. (Eds.), Current Developments in Bioerosion. Springer, Berlin Heidelberg, pp. 279 - 303.","Maher, J., (2011) The phylogeographic population structure of the oval urchin, Echinometra mathaei in KwaZulu-Natal. Unpublished Master thesis. University of KwaZulu-Natal.","Rahman, M. A. & Uehara, T. (2004) Interspecific hybridization and backcrosses between two sibling species of Pacific sea urchins (genus Echinometra) on Okinawan intertidal reefs. Zoological Studies-Taipei, 43 (1), 93 - 111."]}

Closely related sea urchin species in the genus Echinometra from Hawaii and Guam have strong species-specificity of fertilization. Crosses between the two species found in Hawaii, E. mathaei and E. oblonga, were compared in order to determine which steps of gamete interaction are responsible for fertilization barriers. The acrosome reaction, attachment of sperm to eggs, and fusion of sperm and egg membranes were measured in crosses between species and compared to within-species controls. In all crosses, eggs induced the acrosome reaction in 50-100% of sperm within 20 s. However, eggs bound about 3-5 times fewer heterospecific than conspecific sperm. In addition, electrical continuity between heterospecific gametes was achieved rarely under conditions that allowed conspecific gametes to achieve it readily. Only two sperm-egg fusion events were recorded in more than 80 min of heterospecific sperm interaction on 22 eggs. Accordingly, species-specific fertilization in these urchins results firstly from reduced attachment of the heterospecific sperm acrosomal process to the egg vitelline layer, and secondly from inability of attached heterospecific sperm to develop continuity with the egg plasma membrane. At both of these steps, incompatibilities are reciprocal. Thus a barrier to gene flow is mediated by molecular interactions during a specific part of the fertilization process, as the sperm acrosomal surface and the egg vitelline layer contact each other. Recognition molecules mediating these steps of fertilization may be capable of relatively rapid change, leading to species-specificity of fertilization.

Softer rocks in the intertidal zones of southern Japan are occasionally excavated by the rock-boring sea urchin, Echinostrephus molaris, and the pits are often succeeded by non-boring sea urchins, Anthocidaris crassispina and Echinometra tsumajiro after the death of Ec. molaris. Although the rock-boring sea urchin can fold their thin spines and retreat deeply into the pit bottoms, non-boring sea urchins with stouter spines cannot retreat deeply, thus, leaving spaces between their spines and the pit wall. To evaluate the uniqueness of these pits as microhabitats, we conducted an extensive census of biota both inside and outside of the pits occupied by rock-boring and non-boring sea urchins in tidal pools at Shirahama in southern Japan (33°69′51″N, 135°33′58″E). Macrophytes were only observed outside the pits, whereas sessile filter feeders and detritus feeders were found at similar frequencies in all of the microhabitats. The abundance and species richness of algal grazers and carnivores, however, were significantly higher in outside and inside the pits occupied by non-boring sea urchins compared to pits occupied by rock-boring sea urchins. The pit occupied by a non-boring sea urchin was specifically inhabited by a limpet-like trochid snail, Broderipia iridescens, the biology of which is almost completely unknown. Our data suggest that this trochid species is the first example of obligate inquiline with a non-boring pit-inhabiting sea urchin, adapted to the life in the pits, where the limpet benefit by sneaking in the gap between the pit wall and sea urchin spines, escaping from contact with the spines and being protected from attack by predaceous muricid snails.

In spite of the efforts invested in the search for the environmental factors that regulate discrete breeding periods in marine invertebrates, they remain poorly understood. Here, we present the first account of the annual reproductive cycle of the pantropical sea urchin Echinometra sp. from the Gulf of Aqaba/Eilat (Red Sea) and explore some of the main environmental variables that drive echinoid reproduction. Monthly measurements of gonado-somatic indexes and histological observations of 20 specimens revealed a single seasonal reproductive cycle, with gametogenesis in males and females being highly synchronized. Gametogenesis commenced in June and peak spawning occurred between September and October. Gonado-somatic indexes were significantly correlated with seawater temperatures but not with photoperiod. The latter cycle lagged behind the gonado-somatic cycle by two months, suggesting that the onset of gametogenesis corresponds to shortening day length, while spawning may be driven by warming seawater temperatures. Gonads remained quiescent throughout the winter and spring (January through May) when temperatures were at their lowest. Chlorophyll-a concentrations increased significantly in the months following spawning (October through January). These high concentrations are indicative of high phytoplankton abundance and may reflect the increase in food availability for the developing larvae. Of the external test dimensions, length presented the highest correlation to body weight, indicating length as the best predictor for body size in Echinometra. Neither sexual dimorphism nor size differences between males and females were detected, and the sex ratios were approximately 1:1 in three distant Echinometra populations. Environmentally regulated reproduction, as occurs in sea urchins, might face severe outcomes due to anthropogenic disturbances to the marine environment. Consequently, there is a need to deepen our understanding of the mechanisms that drive and regulate this process in broadcast-spawning species.

Increased atmospheric CO2 will have a twofold impact on future marine ecosystems, increasing global sea surface temperatures and uptake of CO2 (Ocean Acidification). Many experiments focus on the investigation of one of these stressors, but under realistic future climate predictions, these stressors may have interactive effects on individuals. Here, we investigate the effect of warming and acidification in combination. We test for interactive effects of potential near-future (2100) temperature (+2 to 3 °C) and pCO2 (~860–940 μAtm) levels on the physiology of the tropical echinoid Echinometra sp. A. The greatest reduction in growth was under simultaneous temperature and pH/pCO2 stress (marginally significant temperature × pH/pCO2 interaction). This was mirrored by the physiological data, with highest metabolic activity (measured as respiration and ammonium excretion) occurring at the increased temperature and pCO2 treatment, although this was not significant for excretion. The perivisceral coelomic fluid pH was ~7.5–7.6, as typical for echinoids, and showed no significant changes between treatments. Indicative of active calcification, internal magnesium and calcium concentrations were reduced compared to the external medium, but were not different between treatments. Gonad weight was lower at the higher temperature, and this difference was more distinct and statistically significant for males. The condition of the gonads assessed by histology declined in increased temperature and low pH treatments. The Echinometra grew in all treatments indicating active calcification of their magnesium calcite tests even as carbonate mineral saturation decreased. Our results indicate that the interactive temperature and pH effects are more important for adult echinoids than individual stressors. Although adult specimens grow and survive in near-future conditions, higher energy demands may influence gonad development and thus population maintenance.

Echinoidea (Phylum Echinodermata) is an aquatic biota that has economic value both economic and ecologic. Echinoidea has the characteristics of thorns which can be used as one of the characters in identification and classification. One of classify Echinoidea is to use the numerical-phenetic method. This method was groups each species according to the morphological similarities observed and account. This study aims to determine the types of Echinoidea and its important to grouping because it has important economic value in the fisheries sector and in conducting the data collection of Echinoidea biodiversity. This study used 7 species of Echinoidea namely Tripneustes sp., Euchinotrix sp., Euchinometra sp., Diadema sp., Stomopneustes sp., Heterocentrotus sp., and Colobocentrotus sp. This study used descriptive qualitative method. Analysis data used MVSV 3.1 application for similarity matrix (Simple Matching Coefficient and Jacard Coefficient) and dendogram. The results showed thorns as a characteristic in the classification of Echinoidea. Echinoidea classification shows two groups that have the highest value, namely Euchinotrix sp., And Diadema sp with 80% similarity value and Colobocentrotus sp with Echinometra, sp which is 76% (Simple Matching Coefficient). Whereas based on Jacard Coefficient the two groups have the same similarity value of 53%. Keywords: numeric-fenetic, echinoidea, similarity

Echinococcosis (hydatid cyst) is a zoonotic disease in sheep, cattle, pigs, rats, and humans that is caused by larvae of the tapeworm Echinococcus granulosus. Several studies have shown that invertebrates exhibit activity against various parasites, but no studies are available of effects of extracts of the sea urchin Echinometra mathaei on hydatid cysts. Here, E. mathaeis gonad extracts were investigated for their effects on hydatid cysts, in the absence and presence of TiO2 nanoparticles. Different concentrations of E. mathaeis gonad extracts with and without TiO2 were applied for different times and the scolicidal activity of each of these conditions was determined on viable protoscolices. 15 μg/ml gonad extract + TiO2 was sufficient to kill 84% of the protoscolices after 60 min incubation. In vivo studies were performed on mice injected with E. granulosus protoscolices. Gonad extracts and gonad extracts combined with TiO2 were given by oral gavage for a period of 3 months. Combined application of extract and TiO2 increased the treatment efficiency, as shown by the reduction in number, size and volume of the cysts. Thus, sea urchin gonad extracts combined with TiO2 nanoparticles have anti-hydatic and scolicidal effects.

Planktotrophic larvae of marine invertebrates develop and grow by utilizing a com- bination of endogenous materials contained in the egg and exogenous food consumed during development. In general, larger eggs contain more reserves for morphogenesis and metabolism than smaller eggs. Interspecific comparisons among planktotrophic echinoderms have generally found that increased maternal provisioning decreases the length of development in the plankton, leading to the widely held idea that large eggs are likely to be selectively favored in low-food or high-mortality environments. Despite long interest in these patterns, however, few studies have examined how exogenous and endogenous supplies interactively affect larval development in phylogenetically controlled and environmentally relevant contexts. We investigated the direct and interactive effects of both endogenous egg materials and exogenous food supply on larval performance of 3 closely related tropical sea urchin species (Echinometra spp.). We found that egg size was positively correlated with egg energy among these 3 species, and that larvae of species with larger (and more energy-rich) eggs developed more rapidly than those from smaller (and lower-energy) eggs. Likewise, across species, larvae fed higher rations grew more rapidly than those fed less. Length of development was most strongly affected by food level in the species with the smallest eggs. Compared to the lowest food treatment, satiating levels shortened development by 9, 7, and 4 d for E. vanbrunti, E. lucunter, and E. viridis, respectively (listed in order of increas- ing egg energy). Our study supports the hypothesis that the growth and development of larvae are more strongly affected by exogenous food availability when they develop from lower-energy eggs than when larvae develop from energy-rich eggs.

Marine organisms exhibit substantial life-history diversity, of which egg size is one fundamental parameter. The size of an egg is generally assumed to reflect the amount of energy it contains and the amount of per-offspring maternal investment. Egg size and energy are thought to scale isometrically. We investigated this relationship by updating published datasets for echinoderms, increasing the number of species over those in previous studies by 62%. When we plotted egg energy versus egg size in the updated dataset we found that planktotrophs have a scaling factor significantly lower than 1, demonstrating an overall trend toward lower energy density in larger planktotrophic eggs. By looking within three genera, Echinometra, Strongylocentrotus, and Arbacia, we also found that the scaling exponent differed among taxa, and that in Echinometra, energy density was significantly lower in species with larger eggs. Theoretical models generally assume a strong tradeoff between egg size and fecundity that limits energetic investment and constrains life-history evolution. These data suggest that the evolution of egg size and egg energy content can be decoupled, possibly facilitating response to selective factors such as sperm limitation which could act on volume alone.

The rising concentration of atmospheric CO2 by anthropogenic activities is changing the chemistry of the oceans, resulting in a decreased pH. Several studies have shown that the decrease in pH can affect calcification rates and reproduction of marine invertebrates, but little attention has been drawn to their immune response. Thus this study evaluated in two adult tropical sea urchin species, Lytechinus variegatus and Echinometra lucunter, the effects of ocean acidification over a period of 24h and 5days, on parameters of the immune response, the extracellular acid base balance, and the ability to recover these parameters. For this reason, the phagocytic capacity (PC), the phagocytic index (PI), the capacity of cell adhesion, cell spreading, cell spreading area of phagocytic amebocytes in vitro, and the coelomic fluid pH were analyzed in animals exposed to a pH of 8.0 (control group), 7.6 and 7.3. Experimental pH's were predicted by IPCC for the future of the two species. Furthermore, a recovery test was conducted to verify whether animals have the ability to restore these physiological parameters after being re-exposed to control conditions. Both species presented a significant decrease in PC, in the pH of coelomic fluid and in the cell spreading area. Besides that, Echinometra lucunter showed a significant decrease in cell spreading and significant differences in coelomocyte proportions. The recovery test showed that the PC of both species increased, also being below the control values. Even so, they were still significantly higher than those exposed to acidified seawater, indicating that with the re-establishment of the pH value the phagocytic capacity of cells tends to restore control conditions. These results demonstrate that the immune system and the coelomic fluid pH of these animals can be affected by ocean acidification. However, the effects of a short-term exposure can be reversible if the natural values ​​are re-established. Thus, the effects of ocean acidification could lead to consequences for pathogen resistance and survival of these sea urchin species.

Two reef margin species of tropical sea urchins, Echinometra sp. C (Ec) and Echinometra oblonga (Eo), occur sympatrically on Okinawa intertidal reefs in southern Japan. Hybridization between these species was examined through a series of cross-fertilization experiments. At limited sperm concentrations, where conspecific crosses reached near 100% fertilization, both heterospecific crosses showed high fertilization rates (81%-85%). The compatibility of the gametes demonstrated that if gamete recognition molecules are involved in fertilization of these species, they are not strongly species-specific. We found that conspecific crosses reached peak fertilization levels much faster than did heterospecific crosses, indicating the presence of a prezygotic barrier to hybridization in the gametes. Larval survival, metamorphosis, and juvenile and adult survival of hybrid groups were nearly identical to those of their parent species. Hybrids from crosses in both directions developed normally through larval stages to sexually mature adults, indicating that neither gametic incompatibility nor hybrid inviability appeared to maintain reproductive isolation between these species. In adults, Ec×Ec crosses gave the highest live weight, followed by Eo (ova)×Ec (sperm), Ec (ova)×Eo (sperm), and Eo×Eo. Other growth performance measures (viz., test size, Aristotle's lantern length, and gonad index) of hybrid groups and their parental siblings showed the same trends. The phenotypic color patterns of the hybrids were closer to the maternal coloration, whereas spine length, tube-foot and gonad spicule characteristics, pedicellaria valve length, and gamete sizes showed intermediate features. Adult F(1) hybrids were completely fertile and displayed high fertilization success in F(1) backcrosses, eliminating the likelihood that hybrid sterility is a postzygotic mechanism of reproductive isolation. Conversely, intensive surveys failed to find hybrid individuals in the field, suggesting the lack or rarity of natural hybridization. This strongly suggests that reproductive isolation is achieved by prezygotic isolating mechanism(s). Of these mechanisms, habitat segregation, gamete competition, differences in spawning times, gametic incompatibility or other genetic and non-genetic factors appear to be important in maintaining the integrity of these species.

An analysis of five Holocene sediment cores from Belize atoll lagoons has revealed a possible mass mortality of the Caribbean sea urchins Diadema antillarum and Echinometra sp. during 6400–6100, 4000, and 1300 yr BP. Event layers were identified by quantifying echinoid fragments in Holocene sediments. Peaks of echinoid abundance were dated radiometrically. There are two explanations for the fact that echinoderm-rich layers cannot be correlated among the three atoll lagoons. First, die out was not as widespread as the 1983–84 event that led to mass mortality of Diadema in the Caribbean. Possibly, local environmental transitions in lagoonal circulation patterns and changes in temperature and precipitation in the study area were responsible for echinoid mass mortality in the Holocene of Belize. Second, echinoid mass mortality is not necessarily implied in the composition of contemporaneous reef sediments. Comparable studies on Holocene corals in the area also suggest that turnover events have repeat...

Background The metabolic rate of consumers is a key driver of ecosystem dynamics. On coral reefs, herbivorous echinoids consume fleshy algae, facilitating the growth of reef-building calcified organisms; however, little is known about differences among species in their metabolic and functional ecology. Here, we used log-linear (log-log) regression models to examine the allometric scaling of mass and routine metabolic rate for five common herbivorous echinoids on a Hawaiian coral reef: Echinothrix calamaris, E. diadema, Echinometra matthaei, Heterocentrotus mammillatus, and Tripneustes gratilla. Scaling relationships were then contrasted with empirical observations of echinoid ecology and general metabolic theory to broaden our understanding of diversity in the metabolic and functional ecology of tropical herbivorous echinoids. Results Test diameter and species explained 98% of the variation in mass, and mass and species explained 92.4% and 87.5% of the variation in individual (I) and mass-specific (B) metabolic rates, respectively. Scaling exponents did not differ for mass or metabolism; however, normalizing constants differed significantly among species. Mass varied as the cube of test diameter (b = 2.9), with HM exhibiting a significantly higher normalizing constant than other species, likely due to its heavily-calcified spines and skeleton. Individual metabolic rate varied approximately as the 2/5 power of mass (γ = 0.44); significantly smaller than the 3/4 universal scaling coefficient, but inclusive of 2/3 scaling. E. calamaris and H. mammillatus exhibited the lowest normalizing constants, corresponding with their slow-moving, cryptic, rock-boring life-history. In contrast, E. calamaris, E. diadema, and T. gratilla, exhibited higher metabolic rates, likely reflecting their higher levels of activity and ability to freely browse for preferred algae due to chemical anti-predator defenses. Thus, differences in metabolic scaling appeared to correspond with differences in phylogeny, behavior, and ecological function. Such comparative metabolic assessments are central to informing theory, ecological models, and the effective management of ecosystems.

Background: Marine organisms produce a variety of compounds with pharmacological activities, including anticancer effects. They contain several secondary metabolites with interesting biological activities. This study attempted to find cytotoxicity of Hexane, Dichloromethane and Butanol partitions of Holothuria leucospilota and Echinometra mathaei. Materials and Methods: H. leucospilota and E. mathaei were collected from Persian Gulf. The animals were extracted by maceration with methanol-ethyl acetate (1:1). The H. leucospilota extract was partitioned by Kupchan method to hexane, dichloromethane, butanol, and water partitions. The cytotoxic activity of the extracts was investigated against HeLa (cervical cancer) and human umbilical vein endothelial cells cell lines by mitochondrial tetrazolium test assay after 72 h. Results: The cell survivals of HeLa cell were decreased by increasing the concentration of extracts. A significant reduction in cell viability at the doses of 30 (μg/ml) of dichloromethane (DCM) partition, 0.3, 3, and 30 (μg/ml) of ButOH partitions of sea cucumber, and 0.5 (μg/ml) of E. mathaei was observed. The median growth inhibitory concentration value of Hex, DCM, ButoH, and water partitions were 0.301, 0.21, 2.29, and 0.229 μg/ml, respectively. Conclusion: This study reveals that different partitions of H. leucospilota and total extract of E. mathaei have cytotoxic activity against cancer cell lines. More study is necessary to find the active metabolites in the more active partitions.

Bindin, a protein involved in sea urchin sperm-egg recognition and adhesion, is under positive selection in genera with sympatric species but evolves neutrally in genera in which all species are allopatric. This pattern has led to suggestions that reinforcement may be the source of the observed selection. Reproductive character displacement, or increased divergence of reproductive characters in areas where closely related species overlap, is often a consequence of reinforcement and has been shown to be present in one Indo-Pacific species of the genus Echinometra. In the Atlantic species of the same genus, positive selection has been shown to act on bindin of Echinometra lucunter. To examine whether the source of this selection is reinforcement, we determined variation on the first exon of bindin in E. lucunter in the Caribbean, where it is sympatric with Echinometra viridis, and in the rest of the Atlantic, where E. viridis is absent. There was no differentiation between bindin sequences from the two geographic regions; similar levels of positive selection were found to be acting in both areas. The similarities were not due to gene flow; mitochondrial DNA from the two regions indicates that E. lucunter populations most likely originated in the Atlantic and have not exchanged genes with Caribbean populations for approximately 200,000 years. The lack of evidence of stronger selection on bindin of E. lucunter in areas of sympatry with its sister species suggests that the source of selection is not reinforcement. Processes acting within species, such as sexual selection, sperm competition, or sexual conflict, are more likely to be involved in the evolution of this molecule.

SUMMARY The larval skeletons of sea urchins show considerable morphological diversity, even between closely related species, although the evolutionary history and functional significance of this diversity are poorly understood. To infer the evolutionary history of the skeletal morphology, we focused on echinometrid species for which the morphological variation in larval skeletons had been investigated qualitatively and quantitatively. We reconstructed the phylogenetic relationships among 14 echinometrid species based on mitochondrial ND1 and ND2 genes and mapped the morphological characters onto the resultant trees. The monophyly of each genus in the Echinometridae was well supported by our results, as was the close affinity between Colobocentrotus, Heterocentrotus, and Echinometra. The mapping of the morphological characters of the larval skeletons indicated that the length, direction, and density of spines on the postoral rods was well conserved in each group of Echinometridae and that the abundance of spines and the size and shape of the body skeleton changed relatively frequently and hence were less conserved. In Echinometrid species, morphological variation in relatively unconserved features tends to be associated with latitudinal distributions, rather than phylogenetic relationships, indicating that the morphological diversity of larval skeletons could have been caused by adaptation to the habitat environment. Some morphological differences, however, seem to be nonfunctional and generated by the constraints on larval skeletogenesis. Thus, echinometrid species can be a good model with which to study the evolutionary history from both ecological and developmental standpoints.

Do changes in food resources lead to evolutionary changes in phenotypic plasticity or in different constant phenotypes? I addressed this question by studying plasticity of larval feeding arms for "geminate species pairs" in three echinoid genera. These closely related species were geographically isolated when the Panamanian Isthmus raised 2.8-3.1 million years ago, creating two different food level environments: high but variable food levels in the eastern Pacific versus chronically low food levels in the western Caribbean. I reared larvae of geminate species in different replicated food environments for 10 days postfertilization, collected morphological measurements of individual arm and body lengths, and calculated degrees of plasticity of relative arm length for each species. In contrast to previous studies with temperate echinoids, there was no significant plasticity of arm length in either the Pacific or Caribbean species considered here. Caribbean species, however, had significantly longer relative arm lengths than Pacific species, regardless of food levels. These results suggest that historical changes in food levels have led to the evolution of constant rather than plastic differences between Pacific and Caribbean echinoids. The evolution of plasticity may be limited by the timing of reproduction or by egg size in this system.

Summary Sea urchins of the genus Echinometra are abundant on reef flats in southern Japan. The Okinawan Echinometra is divided into four sympatric and closely related species, Echinometra tsumajiroi (Ea), Echinometra mathaei (Eb), Echinometra ryukyuensis (Ec), and Echinometra oblonga (Ed). To obtain further information of these four species, this study examined the effect of temperature on the interactions between eggs and spermatozoa. Fertilization in all four Echinometra species showed marked temperature dependence. Temperatures above 15°C were required for fertilization and fertilization was virtually zero at temperatures below 10°. Furthermore, the acrosome reaction of spermatozoa in Ea, Eb, Ec and Ed induced by egg-jelly was influenced by temperature. The acrosome reaction hardly occurred at 0°C in the four species, and the proportion of reactive spermatozoa treated with sea water containing egg-jelly increased with temperature to a maximum at 20° but was lower at 30°. The study did not reveal any su...

Summary This study examined gonadal maturation in the sea urchin, Echinometra tsumajiroi, in relationship to body size. In the breeding season, E. tsumajiroi were collected and divided into six groups based on the length of the major axis (LM) as a measure of body size: Group 1 (6–10 mm in LM), Group 2 (11–15 mm in LM), Group 3 (16–20 mm in LM), Group 4 (21–25 mm in LM), Group 5 (26–30 mm in LM), and Group 6 (> 31 mm in LM). Although gonads were present in individuals larger than 8 mm in LM, the germ cells were undifferentiated in Group 1. Gonadal sex differentiation was first seen in Group 2: a few young oocytes appeared at the periphery of the ovary, and both spermatogonia and spermatocytes were also observed at the periphery of the testis. As size increased from Group 3 to Group 4, more mature germ cells such as ripe ova or spermatozoa were observed in ovaries and testes. In Group 5, the ovaries and testes were filled with a large number of mature eggs and spermatozoa, respectively. Spawning could be i...

Hybridization between Echinometra sp. A (Ea) and Echinometra mathaei (Em) was examined through cross fertilization and rearing experiments to evaluate the aquaculture potential of hybrids. Mean performance traits of fertilization, larval survival, metamorphosis, and recovery of juveniles Em (ova)×Ea (sperm) and Ea (ova)×Em (sperm) hybrids were not significantly different from each other but were significantly lower than either of their conspecific controls, Ea×Ea and Em×Em. Percent survival from metamorphosis to 3-month-old juveniles at recovery was approximately 63% for hybrids and approximately 74% for parents. Postzygotic isolating mechanisms were not large enough to cause developmental incompatibility or hybrid survival. Growth of postmetamorphic hybrids was significantly higher than that of conspecific controls. After culture for 2 years, the mean weight gained by Ea×Ea, Em×Ea, Ea×Em, Em×Em was 41.1±0.8, 50.5±0.4, 49.8±0.3, and 34.3±0.2 g, respectively. Both reciprocal hybrids, Em×Ea and Ea×Em had significantly faster growth than the superior parent (Ea×Ea) and inferior parent (Em×Em). Other growth parameters such as final weight, weight gain (%), specific growth rate (SGR) (%/day) and test size had the same trends as weight gain. Production of gonads was significantly lower in slow-growing Em×Em (7.5±0.1 g) than the fast-growing Ea×Ea (9.1±0.4 g). Reciprocal hybrids contained significantly larger amount of gonads (12.1±0.1 g in Em×Ea and 11.9±0.2 g in Ea×Em) than conspecific controls. Gonad production showed an increase of 45% in F1 hybrids (mean of both hybrids) over mid parents and an increase of 34%, 63% and 47% in F1 hybrid of Em×Ea and 31%, 60%, and 44% in F1 hybrid of Ea×Em over the superior (Ea×Ea), inferior (Em×Em) and mid parents, respectively. Survival was similar in Em×Em (87%) and Ea×Ea (86%), followed by Em×Ea (79%), and Ea×Em (78%). Despite this, survival was lower in the reciprocal hybrids; the values are very close to their conspecific controls. Therefore, body growth, gonad production and survival indicate hybrids in either direction were viable in laboratory conditions and showed parental heterosis. Mean heterosis for final body weight, weight gain, percent weight gain and test size of Em×Ea and Ea×Em hybrids was not differed significantly between hybrid groups, but a significant difference in heterosis for SGR values of Em×Ea and Ea×Em was found. Mean heterosis for gonad weight and gonad index of Em×Ea (1.5±0.03 and 1.1±0.02) and Ea×Em (1.4±0.06 and 1.1±0.03) was not significantly different. The superiority of these growth traits of the hybrid groups over their parental values indicates positive heterosis (hybrid vigor). Hence hybrids in both directions appear to have considerable potential for use in aquaculture.

Conspecific sperm precedence occurs when females are exposed to sperm from males of multiple species, but preferentially use sperm of a conspecific. Conspecific sperm precedence and its mechanisms have been documented widely in terrestrial species, in which complex female behaviors or reproductive tract morphologies can allow many opportunities for female choice and sperm competition, however, the opportunity for conspecific sperm precedence in free spawning marine invertebrates has been largely ignored. Two sea urchin species, Echinometra oblonga and E. sp. C, have high levels of interspecific fertilization in no-choice lab crosses, but no natural hybrids have been found. We performed competitive fertilization assays to test for conspecific sperm precedence and found that eggs of both species showed a marked preference for conspecific sperm when fertilized with heterospecific sperm mixtures. Strong rejection of heterospecific sperm would not have been predicted from no-choice assays and helps explain the lack of natural hybrids. We also found significant variation in hybridization success among crosses. Conspecific sperm precedence in free spawning invertebrates shows that the simple surfaces of eggs and sperm provide ample opportunity for egg choice and sperm competition even in the absence of intricate behavior or complex reproductive morphologies.

Interspecific and intraspecific morphological and fertilization variations were studied in three sibling species of Echinometra (known as sp. B, C and D) found off the coast of Okinawa, Japan. Eggs from C and D were readily fertilized by sperm from all three color morphs of B when the sperm concentrations were high, but no fertilization was observed when sperm of the former were mixed with eggs from the latter. Under limiting sperm concentrations, however, both C and D were incapable to fertilize reciprocally with B. In contrast, crossing between C and D produced fertilization membrane at high and limiting sperm concentrations in both directions. Interspecific crosses between B vs. C and B vs. D clearly showed that these combinations were reproductively isolated in contrast to that observed for crossing between C and D. Interestingly, intraspecific fertilization of B showed considerable morphological variation in addition to variability in fertilization success. Intraspecific fertilization and morphological variations may occur due to a number of genetic and/or non-genetic factors. While the underlying cause(s) remain to be elucidated, the results of the present study suggest that B is now speciating very slowly.

SUMMARYAlthough eyes are generally considered necessary for image resolution, a diffuse photoreceptive system with directional sensitivity may also have this ability. Two species of the echinoid genus Echinometra were tested for spatial vision by examining their ability to locate and move towards targets of different sizes. The echinoids were significantly oriented(P

Summary Sea urchins of the genus Echinometra are abundant on Okinawa reef flats in southern Japan. The Okinawan Echinometra is subdivided into four sympatric and closely related species (Ea, Eb, Ec, and Ed). To elucidate the relationships between them, we have examined the effect of egg jelly on the acrosome reaction, a process sea urchin spermatozoa undergo before fertilization. When Echinometra spermatozoa were treated with egg jelly, the acrosome reaction in each species was, as expected, effectively induced by jelly from the same species. The acrosome reaction in Ed spermatozoa was induced by egg jelly regardless of species, whereas the acrosome reaction of Eb spermatozoa took place only when it was treated with Eb egg jelly. The acrosome reaction of Ea spermatozoa was induced by jelly from species Ea or Eb, while Ec spermatozoa responded to egg jelly from Ea, Ec, or Ed. These results suggest that the separation of these four species of Okinawan Echinometra has taken place quite recently. An additiona...