Arm Deflation in the Rare Thorny Sea Star, Poraniopsis inflatus (Asteroidea: Poraniidae), A Defensive Response to other Sea Stars?

The Thorny Sea Star, Poraniopsis inflatus, is rare in the Northeastern Pacific. It lacks pedicellariae or other overt defenses for protection against other predatory sea stars. During an earlier study, a P. inflatus confronted by an asteroid-eating sea star was observed to exhibit a possible defensive reaction: "arm deflation." It was 15 years before another P. inflatus specimen could be obtained and that hypothesis confirmed by testing with individuals of 18 other sea-star species. Contact with individuals of four predatory sea-stars, Asterina miniata, Crossaster papposus, Solaster dawsoni, and Pycnopodia helianthoides, elicited the reaction in the P. inflatus. The specimen collapsed ("deflated") an arm closest to the predatory star, possibly by expelling coelomic fluid, exposing more of its embedded thorns (hence its common name) which may discourage other sea stars from attempting to eat it

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Global Diversity and Phylogeny of the Asteroidea (Echinodermata)

Members of the Asteroidea (phylum Echinodermata), popularly known as starfish or sea stars, are ecologically important and diverse members of marine ecosystems in all of the world's oceans. We present a comprehensive overview of diversity and phylogeny as they have figured into the evolution of the Asteroidea from Paleozoic to the living fauna. Living post-Paleozoic asteroids, the Neoasteroidea, are morphologically separate from those in the Paleozoic. Early Paleozoic asteroid faunas were diverse and displayed morphology that foreshadowed later living taxa. Preservation presents significant difficulties, but fossil occurrence and current accounts suggests a diverse Paleozoic fauna, which underwent extinction around the Permian-Triassic interval was followed by re-diversification of at least one surviving lineage. Ongoing phylogenetic classification debates include the status of the Paxillosida and the Concentricycloidea. Fossil and molecular evidence has been and continues to be part of the ongoing evolution of asteroid phylogenetic research. The modern lineages of asteroids include the Valvatacea, the Forcipulatacea, the Spinlosida, and the Velatida. We present an overview of diversity in these taxa, as well as brief notes on broader significance, ecology, and functional morphology of each. Although much asteroid taxonomy is stable, many new taxa remain to be discovered with many new species currently awaiting description. The Goniasteridae is currently one of the most diverse families within the Asteroidea. New data from molecular phylogenetics and the advent of global biodiversity databases, such as the World Asteroidea Database (http://www.marinespecies.org/Asteroidea/) present important new springboards for understanding the global biodiversity and evolution of asteroids

NEW TRIASSIC ASTEROIDEA (ECHINODERMATA) SPECIMENS AND THEIR EVOLUTIONARY SIGNIFICANCE

The Paleozoic-Mesozoic transition saw the disappearance of asteroid stem groups and the ascent of the crown group, but late Paleozoic and Triassic asteroids are rare and transition events are poorly documented. Three new Middle and Late Triassic specimens augment existing data; included are a specimen of Trichasteropsis weissmanni from Germany, a specimen of Trichasteropsis? sp. indet. from Italy, and a possible member of the extant Poraniidae from Slovenia. Presence of a small ossicle at the interbrachial midline and adjacent to the marginal series of the new T. weissmanni specimen is consistent with similar expressions not only of other trichasteropsids but also occurrence of two interbrachial ossicles in Paleozoic, stem-group asterozoans; presence is in turn consistent with a hypothesis of derivation of the axillary/odontophore coupling from two ossicles rather than direct derivation of the crown-group odontophore from a single stem-group axillary. Morphology of Trichasteropsis? sp. indet., including, for example, the evenly-tapering arms are reminiscent of those of diverse crown-group asteroids whereas the enlarged distal arms of T. weissmanni are unique, the morphology of T? sp. indet. thereby potentially indicative of a plesiomorphic, stemward positioning within the Trichasteropsiidae. The range of the Poraniidae is tentatively extended to the Carnian. Similarities shared by the Poraniidae and the Trichasteropsiidae suggest stemward positioning within crown-group diversification; however, known Triassic fossils do not appear closely related to extant taxa identified in recent molecular studies as basal within the crown-group. A temperate climate is suggested as preferred by the Triassic asteroids rather than a tropical, warmer one

Energetics and development modes of Asteroidea (Echinodermata) from the Southwestern Atlantic Ocean including Burdwood Bank/MPA Namuncurá

Reproduction is a highly expensive process that during gonadal development requires an important supply of nutrients. The allocation of energy can vary throughout the reproductive cycle, between sexes and development modes. During research cruise aboard the RV Puerto Deseado in April 2016, we collected fifteen species of sea stars from the southernmost region of Argentina. The main purposes of the present study were threefold: first, to revise and report novel information on the reproductive strategies and energetic density (ED) of body components from the asteroids of the southwestern Atlantic Ocean including Burdwood Bank/ MPA Namuncurá; second, to compare the ED of these body components across species with contrasting reproductive strategies; third, to provide a tool to estimate the ED from dry mass of organs of the sea star species examined. Ovaries of Diplopteraster verrucosus (a brooder with a nidamental chamber) revealed a significantly greater ED than did the testes (29.81 ± 1.38 and 17.76 ± 1.59, respectively). In Glabraster antarctica (a broadcaster with yolky eggs and facultative planktotrophic larvae), the gonads had EDs of 25.78 ± 3.16 and 19.21 ± 0.52 (females and males, respectively). While in Peribolaster folliculatus (a broadcaster with eggs with low yolk content and inferred planktotrophic larvae) there was no significant difference in the ED values between sexes (females: 22.79 ± 1.10 and males: 20.46 ± 1.05). For the pyloric caeca, ED values did not reveal any difference between sexes, although in P. folliculatus, the ED was significantly higher than that for D. verrucosus and G. antarctica (25.90 ± 1.00, 23.03 ± 0.34, and 22.66 ± 0.65, respectively). The body wall had higher ED values in D. verrucosus and P. folliculatus than that for all the sea star species analyzed (46.48 ± 1.63, 51.17 ± 1.34, respectively). Higher ED values in the ovaries could be related to the nutrition of offspring, while differences found in the body wall may reflect the skeletal structure of this body component. This research provides basic information for understanding the differences on energetic allocation when contrasting development modes are considered.Fil: Fraysse, Cintia Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; ArgentinaFil: Pérez, Analía F.. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; ArgentinaFil: Calcagno, Javier Ángel. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Boy, Claudia Clementina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Distribution of asteroid genera (Echinodermata) off South Shetland Islands and the Antarctic Peninsula

Se analizan la frecuencia y distribución de los géneros de Asteroidea en la zona de las islas Shetland del Sur a partir en los datos obtenidos en 24 arrastres con Agassiz efectuados durante la campaña Bentart 95. Las estrellas fueron recogidas en más del 90 % de las estaciones, sobre todo tipo de fondos, con riqueza que osciló entre 0-10 géneros. Los asteroideos encontrados pertenecieron a 27 géneros y 12 familias, siendo Astropectinidae, Goniasteridae y, sobre todo, Asteriidae, las familas con el número más elevado de representantes (3 y 7 géneros, respectivamente). Odontaster Verrill, 1880 y Labidiaster Lütken, 1872, seguidos por Psilaster Sladen, 1885 y Diplasterias Perrier, 1888 presentaron la más amplia distribución y la frecuencia más elevada. Odontaster fue más frecuente hasta 100 m de profundidad y Labidiaster entre 200-300 m. Los géneros más raros fueron Notioceramus Fisher, 1940 y Chitonaster Sladen, 1889, endémicos de aguas antárticas. Las estaciones que mostraron una riqueza más alta (10 géneros) fueron las localizadas cerca de la península antártica y el norte de la isla Livingston. La pobreza de asteroideos fue notable en el interior de la isla Decepción, donde se encontraron sólo tres géneros.Frequency and distribution of asteroid genera in the South Shetlands zone are analysed, based on data from 24 Agassiz trawls carried out during the Bentart 95 Survey. Asteroids were collected at more than 90 % of the stations, on all types of bottoms, with richness per station ranging from 0-10 genera. The specimens belonged to 27 genera and 12 families, with Astropectinidae, Goniasteridae and, above all, Asteriidae having the highest number of representatives (3 and 7 genera, respectively). Odontaster Verrill, 1880 and Labidiaster Lütken, 1872, followed by Psilaster Sladen, 1885 and Diplasterias Perrier, 1888, were found to have the widest distribution and highest occurrence. Odontaster was more frequent to a depth of 100 m, and Labidiaster between 200 and 300 m. The rarest genera were Notioceramus Fisher, 1940 and Chitonaster Sladen, 1889, endemic to Antarctic waters.Stations showing the highest richness (10 genera) were those located near the Antarctic Peninsula and north of Livingston Island. Asteroid poverty was noticeable inside Deception Island, where a mere 3 genera were recorded. As shown by similarity and grouping analysis based on presence-absence data, stations are mainly grouped in relation to genera richness when double absence is considered. These results show the distintiveness of the stations around Deception Island, probably due to its special geological characteristics.Instituto Español de Oceanografí

Species composition of sea stars (Echinodermata: Asteroidea) in the Patagonian Argentinian deep sea, including seven new records: connectivity with sub-Antarctic and Antarctic fauna

The main target of this paper is to improve the knowledge of the species composition of sea stars in Patagonian Argentine deep sea reaching depths of 2062 m. In addition, these results offer us the opportunity to analyze the possible connections between Argentinian marine fauna and adjacent Antarctic areas that have become a topic of interest in the past few years. This work is based on Atlantic Projects’ surveys carried out on an atypical and especially vulnerable marine ecosystems (canyons created from craters collapse by gas leaks). These are profusely impacted by frequent fishing activities, being one of the most important and international fishing grounds, where 887 records (1878 specimens) of 41 species of asteroids were collected in 217 stations ranging from 219 to 2062 m in depth. Seven of those species are proposed as new records: (Diplasterias octoradiata (Studer 1885), Plutonaster bifrons (Wyville Thomson, 1873), Radiaster elegans Perrier, 1881, Anseropoda antarctica Fisher, 1940, Pillsburiaster calvus Mah, 2011, Paralophaster lorioli (Koehler, 1907), Pteraster flabellifer Mortensen 1933). After refining the database built from literature and open-access databases such as OBIS and AntBIF, the new Argentinian asteroids deep-water checklist contains 2198 records from 64 asteroids species including the 7 new records proposed. Most of these 64 species (89.06%) are present in Antarctic-adjacent waters, and after the study of their occurrences at traditional biogeographic entities, our results support the hypothesis that Argentinian waters (in the case of the class Asteroidea) should be considered part of the sub-Antarctic entity.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Funding for open access charge: Universidad de Málaga / CBUA. This work has been funded by ATLANTIS Projects [IEO, Secretary General of Maritime Fishing (SGP) and Economy and Competivity Ministry. Spanish Government (2007–2010)], Puente Projects (Mod.B5) funded by UMA, and Own Found from the Junta de Andalucía, research groups SELUMA

PRELIMINARY CHECKLIST OF THE UNDERSEA FAUNA OF THE ROSS SEA ANTARCTIC CONTINENTAL SHELF BASED ON YO-YO CAMERA SURVEYS

As part of an expedition aboard the Nathaniel B. Palmer RVIB, hundreds of still images were captured of the Ross Sea continental shelf seafloor. Using a crowd-sourced group of experts, we identified the fauna captured in these images, identifying over 1000 organisms to 15 major taxonomic groups (viz., anemones, bivalves, brittle stars, cephalopods, corals, crinoids, crustaceans, fishes, holothurians, isopods, pycnogonids, sea urchins, sea stars, sponges, tunicates). On the basis of the organisms we could identify to genus or species, we compiled a checklist of the fauna from this poorly-known area. The images from this yo-yo camera survey show a diverse community of life that was largely unknown for this sector and may reveal expanded ranges for some species and potentially new ecological information.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/168230/1/UMMP_MP_209-2.pdfMain ArticleSEL

Trophic ecology of peripheral fauna at the Fåvne hydrothermal vent field on the Arctic Mid-Ocean Ridge

Fåvne vent field is one of the most recently discovered vents on the Arctic Mid-Ocean Ridge (AMOR) and consists of both active and inactive vents. It was discovered in 2018, and there are only a few published papers on the area to date. Due to the increasing interest in deep-sea mining of rare earth metals and other minerals at AMOR, there is a race to reduce the knowledge gaps in vent areas to better understand how mining will affect life in the surrounding areas. This thesis aims to understand the food web structure of active hydrothermal vent´s background fauna, investigate how connected and dependent they are to the active vents, and examine how decisions are made when knowledge is lacking. To achieve this, specimens and environmental samples collected from Fåvne were tested for Carbon and Nitrogen stable isotopes to create a food web. In addition, DNA sequences were run to identify if there were any cryptic species among the data set. We collected 29 specimens divided into six groups based on morphological classification: Asconema, Demospongiae, Cladorhiza, Actiniaria, Asteroidea, and Amphipoda. The food web was created and compared to the expected trajectory of a deep-sea habitat. There was no clear indication that the background fauna had any direct connection to the active vents or that the sea floor was a part of the nutrient chain. But there was a large gap between the primary food source and the primary consumer, indicating that the food web lacks one or more trophic levels. This baseline knowledge can be useful for assessing the impact of deep-sea mining as part of a more extensive knowledge base. There will always be knowledge gaps concerning deep-sea ecology and mining hydrothermal vents, and it is, therefore, essential to enlighten and communicate these uncertainties in a transparent manner. And when making decisions, it is important to assess the situation against the best available knowledge. A good principle to use is the precautionary principle, which allows choices to be made based on the best available knowledge and the awareness that the knowledge base may be incomplete and allows for reevaluation if the situation or knowledge should change.MasteroppgaveSDG350MAHF-SD