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  • richardmitnick 7:18 am on May 10, 2021 Permalink | Reply
    Tags: "New marine symbiosis unseen for 270 million years", , , , , University of Warsaw [Uniwersytet Warszawski] (PL)   

    From University of Warsaw [Uniwersytet Warszawski] (PL) and Science Alert (AU) : “New marine symbiosis unseen for 270 million years” 

    From University of Warsaw [Uniwersytet Warszawski] (PL)

    and

    ScienceAlert

    Science Alert (AU)

    30 April 2021

    A symbiotic relationship between two marine lifeforms has just been discovered thriving at the bottom of the ocean, after disappearing from the fossil record for hundreds of millions of years.

    Scientists have found non-skeletal corals growing from the stalks of marine animals known as crinoids, or sea lilies, on the floor of the Pacific Ocean, off the coasts of Honshu and Shikoku in Japan.

    “These specimens represent the first detailed records and examinations of a recent syn vivo association of a crinoid (host) and a hexacoral (epibiont),” the researchers wrote in their paper, “and therefore analyses of these associations can shed new light on our understanding of these common Paleozoic associations.”

    During the Paleozoic era, crinoids and corals seem to have gotten along very well indeed. The seafloor fossil record is full of it, yielding countless examples of corals overgrowing crinoid stems to climb above the seafloor into the water column, to stronger ocean currents for filter-feeding.

    Prof. Mikołaj Zapalski from the UW Faculty of Geology with researchers from Japan and Poland described an ecological “living fossil” unseen for 273 million years. Their article appeared in Palaeogeography, Palaeoclimatology, Palaeoecology.

    1
    Credit: Zapalski et al., Palaeogeography, Palaeoclimatology, Palaeoecology, 2021.

    2
    Credit: Zapalski et al., Palaeogeography, Palaeoclimatology, Palaeoecology, 2021.

    Palaeozoic seafloors were inhabited by numerous organisms interacting with each other. One of these associations was corals growing on sea lilies (crinoids). As corals grew on crinoids, they were lifted above the seafloor, thus profiting from stronger feeding currents. Fossils of crinoid-coral associations are known from Palaeozoic rocks, and the youngest are known from rocks dated from ca. 273 million years ago. While both corals and crinoids are known from younger rocks, such associations are unknown neither from Meso- and Cenozoic strata nor contemporary seas.

    In a research article [above], Prof. Mikołaj Zapalski from the UW Faculty of Geology with collaborators from Japan and Poland described an ecological “living fossil” unseen for 273 million years; non-skeletal corals growing on crinoid stalks. The investigated animals were collected from depths exceeding 100 m near the Pacific coasts of Honshu and Shikoku. The research was conducted using microtomography scanning and revealed that, unlike their Palaeozoic counterparts, recent corals do not modify the host’s skeleton. Despite such differences in the skeletal record, the newly discovered coral-crinoid associations may serve as a good model of relevant Palaeozoic interactions.

    See the full University of Warsaw [Uniwersytet Warszawski] (PL)article here.

    10 MAY 2021
    MICHELLE STARR

    A symbiotic relationship between two marine lifeforms has just been discovered thriving at the bottom of the ocean, after disappearing from the fossil record for hundreds of millions of years.

    Scientists have found non-skeletal corals growing from the stalks of marine animals known as crinoids, or sea lilies, on the floor of the Pacific Ocean, off the coasts of Honshu and Shikoku in Japan.

    “These specimens represent the first detailed records and examinations of a recent syn vivo association of a crinoid (host) and a hexacoral (epibiont),” the researchers wrote in their paper, “and therefore analyses of these associations can shed new light on our understanding of these common Paleozoic associations.”

    During the Paleozoic era, crinoids and corals seem to have gotten along very well indeed. The seafloor fossil record is full of it, yielding countless examples of corals overgrowing crinoid stems to climb above the seafloor into the water column, to stronger ocean currents for filter-feeding.

    Yet these benthic besties disappeared from the fossil record around 273 million years ago, after the specific crinoids and corals in question went extinct. Other species of crinoids and corals emerged in the Mesozoic, following the Permian-Triassic extinction – but never again have we seen them together in a symbiotic relationship.

    Well, until now. At depths exceeding 100 meters (330 feet) below the ocean’s surface, scientists have found two different species of coral – hexacorals of the genera Abyssoanthus, which is very rare, and Metridioidea, a type of sea anemone – growing from the stems of living Japanese sea lilies (Metacrinus rotundus).

    The joint Polish-Japanese research team, led by paleontologist Mikołaj Zapalski of the University of Warsaw in Poland, first used stereoscopic microscopy to observe and photograph the specimens.

    Then, they used non-destructive microtomography to scan the specimens to reveal their interior structures, and DNA barcoding to identify the species.

    They found that the corals, which attached below the feeding fans of the crinoids, likely didn’t compete with their hosts for food; and, being non-skeletal, likely didn’t affect the flexibility of the crinoid stalks, although the anemone may have hindered movement of the host’s cirri – thin strands that line the stalk.

    It’s also unclear what benefit the crinoids gain from a relationship with coral, but one interesting thing did emerge: unlike the Paleozoic corals, the new specimens did not modify the structure of the crinoids’ skeleton.

    This, the researchers said, can help explain the gap in the fossil record. The Paleozoic fossils of symbiotic corals and crinoids involve corals that have a calcite skeleton, such as Rugosa and Tabulata.

    Fossils of soft-bodied organisms – such as non-skeletal corals – are rare. Zoantharia such as Abyssoanthus have no confirmed fossil record, and actiniaria such as Metridioidea (seen as a dry specimen in the image below) also are extremely limited.

    4
    (Zapalski et al., Palaeogeography, Palaeoclimatology, Palaeoecology, 2021)

    If these corals don’t modify the host, and leave no fossil record, perhaps they have had a long relationship with crinoids that has simply not been recorded.

    This means the modern relationship between coral and crinoid could contain some clues as to Paleozoic interactions between coral and crinoid. There’s evidence to suggest that zoantharians and rugose corals share a common ancestor, for instance.

    The number of specimens recovered to date is small, but now that we know they are there, perhaps more work can be done to discover the history of this fascinating friendship.

    “As both Actiniaria and Zoantharia have their phylogenetic roots deep in the Palaeozoic, and coral-crinoid associations were common among Palaeozoic Tabulate and Rugose corals, we can speculate that also Palaeozoic non-skeletal corals might have developed this strategy of settling on crinoids,” the researchers wrote in their paper.

    “The coral-crinoid associations, characteristic of Palaeozoic benthic communities, disappeared by the end of Permian, and this current work represents the first detailed examination of their rediscovery in modern seas.”

    See the full Science Alert (AU) article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    University of Warsaw [Uniwersytet Warszawski] (PL), established in 1816, is the largest university in Poland. It employs over 6,000 staff including over 3,100 academic educators. It provides graduate courses for 53,000 students (on top of over 9,200 postgraduate and doctoral candidates). The University offers some 37 different fields of study, 18 faculties and over 100 specializations in Humanities, technical as well as Natural Sciences.

    It was founded as a Royal University on 19 November 1816, when the Partitions of Poland separated Warsaw from the oldest and most influential University of Kraków. Alexander I granted permission for the establishment of five faculties – law and political science, medicine, philosophy, theology and the humanities. The university expanded rapidly but was closed during November Uprising in 1830. It was reopened in 1857 as the Warsaw Academy of Medicine, which was now based in the nearby Staszic Palace with only medical and pharmaceutical faculties. All Polish-language campuses were closed in 1869 after the failed January Uprising, but the university managed to train 3,000 students, many of whom were important part of the Polish intelligentsia; meanwhile the Main Building was reopened for training military personnel. The university was resurrected during the First World War and the number of students reached 4,500 in 1918. After Poland’s independence the new government focused on improving the university, and in the early 1930s it became the country’s largest. New faculties were established and the curriculum was extended. Following the Second World War and the devastation of Warsaw, the University successfully reopened in 1945.

    Today, University of Warsaw [Uniwersytet Warszawski] (PL) consists of 126 buildings and educational complexes with over 18 faculties: biology, chemistry, journalism and political science, philosophy and sociology, physics, geography and regional studies, geology, history, applied linguistics and Slavic philology, economics, philology, pedagogy, Polish language, law and public administration, psychology, applied social sciences, management and mathematics, computer science and mechanics.

    The University of Warsaw [Uniwersytet Warszawski] (PL) is one of the top Polish universities. It was ranked by Perspektywy magazine as best Polish university in 2010, 2011, 2014 and 2016. International rankings such as ARWU and University Web Ranking rank the university as the best Polish higher level institution. On the list of 100 best European universities compiled by University Web Ranking, the University of Warsaw [Uniwersytet Warszawski] (PL) was placed as 61st. QS World University Rankings previously positioned the University of Warsaw [Uniwersytet Warszawski] (PL) as the best higher level institution among the world’s top 400.

     
  • richardmitnick 8:47 am on April 28, 2021 Permalink | Reply
    Tags: "Mysteriously Slow Pulses From Giant Old Stars May Finally Have an Explanation", , , , , , The red giant star Betelgeuse, University of Warsaw [Uniwersytet Warszawski] (PL)   

    From University of Warsaw [Uniwersytet Warszawski] (PL) via Science Alert (AU) : “Mysteriously Slow Pulses From Giant Old Stars May Finally Have an Explanation” 

    From University of Warsaw [Uniwersytet Warszawski] (PL)

    via

    ScienceAlert

    Science Alert (AU)

    28 APRIL 2021
    MICHELLE STARR

    1
    Artist’s impression of an exoplanet trailing a cloud of dust. Credit: Maciej Szyszko.

    The extremely slow, steady pulsations of light from many red giant stars may finally have an explanation.

    According to a new analysis, these mysterious fluctuations in brightness are not caused by internal processes after all, but by binary companions obscured in clouds of dust siphoned off the dying giants.

    When stars of intermediate mass below around eight times the mass of the Sun reach the twilight of their lives, they go through some pretty dramatic changes.

    When they have fused all the hydrogen in their cores to helium, the nuclear fusion within ceases, and the core starts to contract. This brings more hydrogen into the region immediately around the core, forming a hydrogen shell; then, fusion starts up again, dumping helium into the core. This is called hydrogen shell burning.

    During this time, the outer layers of the star expand – by a lot. When this eventually happens to the Sun, for example, it will expand out past the orbit of Earth. This is the red giant branch of stellar evolution.

    Red giant stars often fluctuate in brightness a little, over regular periods. The red giant star Betelgeuse is a perfect example of this.

    It has several brightness cycles, including one that occurs over around 425 days, and another over around 185 days. These are caused by acoustic waves bouncing around inside the star as it expands, contracts, and expands again.

    The longest of its cycles is more mysterious. It’s what we call a “long secondary period”, and it’s 5.9 years long. Not all giant branch stars have long secondary periods, but a lot of them do – scientists have detected a long secondary period in around a third of all known giant branch stars – and these periods cannot be explained in the same way.

    A few explanations have been put forward for these mysterious thrums in the light of dying stars, including a different kind of internal oscillation, magnetic activity, or the presence of a binary companion.

    To try and get to the bottom of the mystery, a team of astronomers led by Igor Soszyński of the University of Warsaw [Uniwersytet Warszawski] (PL) conducted a close study of red giant stars with long secondary periods. From available survey data, they collated optical and mid-infrared observations of 16,000 of these stars, from which they extracted around 700 stars with a well-defined infrared light curve – a plot of the way the light changes over time – for a closer analysis.

    When comparing the optical and infrared light curves for these 700 stars, something curious emerged. In both light curves for all the stars, there was a large dip, as expected, corresponding to the stars’ dimmer periods. But for around half of the stars, there was a second, shallower dip only in the infrared light curve, exactly opposite the primary dip.

    This, the team said, is an important clue. Mid-infrared light is often produced by dust – it absorbs starlight, and re-emits it at longer wavelengths.

    This can neatly explain what’s happening around the red giant stars. If the star is being orbited by a smaller companion that has siphoned off material from the star and is therefore trailing a long dust cloud, this companion will produce a long, strong dip in starlight at all wavelengths when it passes between us and the star.

    Then, as this dusty object moves around to the side of the star, we will be able to see mid-infrared light as the starlight is absorbed and re-emitted. This mid-infrared light will dip when the binary companion moves behind the star, only to glow again when the companion re-emerges out the other side.

    According to the team’s analysis, the amplitudes of the light curves suggest that the companion is either a very low mass star, or a brown dwarf. But brown dwarfs – stars that didn’t grow large enough to be stars, but grew too large to be planets – are relatively rare.

    If the companions are brown dwarfs, the team said, they could have started their lives as smaller exoplanets, and siphoned material off the red giant stars’ outer envelopes. This suggests that most red giants with long secondary periods are orbited by objects that used to be exoplanets.

    In turn, the researchers said, this finding could allow long secondary period giant branch stars to be used as tracers for studying the planetary population of the Milky Way.

    The team’s research has been published in The Astrophysical Journal Letters.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    University of Warsaw [Uniwersytet Warszawski] (PL), established in 1816, is the largest university in Poland. It employs over 6,000 staff including over 3,100 academic educators. It provides graduate courses for 53,000 students (on top of over 9,200 postgraduate and doctoral candidates). The University offers some 37 different fields of study, 18 faculties and over 100 specializations in Humanities, technical as well as Natural Sciences.

    It was founded as a Royal University on 19 November 1816, when the Partitions of Poland separated Warsaw from the oldest and most influential University of Kraków. Alexander I granted permission for the establishment of five faculties – law and political science, medicine, philosophy, theology and the humanities. The university expanded rapidly but was closed during November Uprising in 1830. It was reopened in 1857 as the Warsaw Academy of Medicine, which was now based in the nearby Staszic Palace with only medical and pharmaceutical faculties. All Polish-language campuses were closed in 1869 after the failed January Uprising, but the university managed to train 3,000 students, many of whom were important part of the Polish intelligentsia; meanwhile the Main Building was reopened for training military personnel. The university was resurrected during the First World War and the number of students reached 4,500 in 1918. After Poland’s independence the new government focused on improving the university, and in the early 1930s it became the country’s largest. New faculties were established and the curriculum was extended. Following the Second World War and the devastation of Warsaw, the University successfully reopened in 1945.

    Today, University of Warsaw [Uniwersytet Warszawski] (PL) consists of 126 buildings and educational complexes with over 18 faculties: biology, chemistry, journalism and political science, philosophy and sociology, physics, geography and regional studies, geology, history, applied linguistics and Slavic philology, economics, philology, pedagogy, Polish language, law and public administration, psychology, applied social sciences, management and mathematics, computer science and mechanics.

    The University of Warsaw [Uniwersytet Warszawski] (PL) is one of the top Polish universities. It was ranked by Perspektywy magazine as best Polish university in 2010, 2011, 2014 and 2016. International rankings such as ARWU and University Web Ranking rank the university as the best Polish higher level institution. On the list of 100 best European universities compiled by University Web Ranking, the University of Warsaw [Uniwersytet Warszawski] (PL) was placed as 61st. QS World University Rankings previously positioned the University of Warsaw [Uniwersytet Warszawski] (PL) as the best higher level institution among the world’s top 400.

     
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