Musellifer leasiae: A new species of Gastrotrich from Antarctica.

The waters of the Southern Ocean, which surrounds Antarctica, are considered to be a hotspot for marine biodiversity, yet only their macrofauna has been extensively studied. The meiobenthos (bottom dwelling organisms larger than single-celled microbes, but still difficult or impossible to see with the naked eye) of this region has been particularly poorly studied, and almost all of the studies which have occurred have been of Nematodes or Crustaceans. To date, twenty species of Tardigrades have been described from the waters around Antarctica, two Gnathostomulids, one of which was only identified to family level, and five Kinorynchs (although a study which should be published later this year is expected to add to this) have been described from this region, but not a single Scalidophoran, Loriciferan, or meiobenthic Priapulid.

Gastrotrichs are a phylum of minute animals, generally less than a millimetre in length, found in interstitial spaces in sediments. Their small size meant that they went unnoticed until the event of microscopy, with the group not being discovered until the 1860s. Despite this unfamiliarity they seem to be ubiquitous in marine sediments, and are also often found in non-marine settings. To date, only a single Gastrotrich, Thaumastoderma antarctica, has been identified from Antarctic waters, although there have been several reports of unidentified Gastrotrichs.

In a paper published in the journal Zootaxa on 17 June 2025, Martin Sørensen of the Natural History Museum of Denmark at the University of Copenhagen, Thiago Araújo of the University of Massachusetts Lowell, Lara Macheriotou and Ulrike Braeckman of the Marine Biology Research Group at Ghent University, Craig Smith of the Department of Oceanography at the University of Hawai’i at Mānoa, and Jeroen Ingels of the Coastal and Marine Laboratory at Florida State University, and the National Institute for Water and Atmospheric Research in Wellington, New Zealand, describe a second species of Gastrotrich from Antarctic waters.

The new species is described from specimens collected in December 2015 and April 2016 from sediment cores collected from depths of between 532 and 701 m in Andvord Bay the west coast of Graham Land, and the Gerlache Strait, which separates the Palmer Archipelago from the Antarctic Peninsula. It is placed within the genus Musellifer, and given the specific name leasiae, in honour of marine biologist  Francesca Leasi in recognition of her numerous contributions to Gastrotrich taxonomy and morphology.

Map showing the sampling stations. (A) Overview of Antarctica, with the Antarctic Peninsula framed. (B) Antarctic Peninsula with sampling area framed. (C) Sampling area with stations. Red star indicates the type locality; yellow dots indicate additional stations with Musellifer leasiae. Sørensen et al. (2025).

Specimens of Musellifer leasiae are between 322 and 415 μm in length, and have a body with a pointed head, a weakly defined neck, a parallel-sided body, and a pair of tapering furcal branches ('tails'). This body is covered by approximately 26 columns of scales, with an average of 45 scales per column. The columns can be divided into eight dorsal columns, two sets of five ventral columns, and eight ventral columns. The ventral surface also has two rows of locomotory cilia.

Line art illustration of Musellifer leasiae, (A) Dorsal view. (B) Ventral view. (C) Close-ups of head scales, anterior-, and posterior trunk scales, and terminal furca scales. Sørensen et al. (2025).

Five species of Musellifer have been described previously; Musellifer delamarei and Musellifer profundus from the Mediterranean, Musellifer tridentatus from the Caribbean, Musellifer reichardti from the Atlantic coast of Florida, and Musellifer sanlitoralis from the San Juan Archipelago in Washington State. Only a single specimen has previously been described from the Southern Hemisphere, a possible specimen of Musellifer profundus, making Musellifer leasiae the first known species in the genus with a Southern Hemisphere, as well as the first species from the Antarctic.

Light micrographs showing overviews and details of holotype NHMD-1801023 (A)-(H) and paratype NHMD-1801024 (I) of Musellifer leasiae. (A) Ventral overview. (B) Body, anterior, U0-32, dorsal view. (C) Body, anterior, U0-32, ventral view. (D) Body, median, U26-55, dorsal view. (E) Body, median, U28-60, dorsal view. (F) Body, posterior, U54-84, dorsal view. (G) Body, posterior, U54-86, ventral view. (H) Caudal furca branches, U67-100, ventral view. (I) Body, posterior, U54-82, focused on adhesive glandular tissue. Abbreviations: agt, adhesive glandular tissue; lcf, locomotory ciliary field; vcb, ventral ciliary bands. Sørensen et al. (2025).

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Magnitude 8.8 Earthquake off the Kamchatka Peninsula

The United States Geological Survey recorded a Magnitude 8.8 Earthquake at a depth of 20.7 km off the southeast coast of the Kamchatka Peninsula in the Russian Far East slightly before 11.25 am local time on Wednesday 30 July 2025 (slightly before 11.25 pm on Tuesday 29 July, GMT). A Magnitude of 8.8 makes this the sixth largest Earthquake ever recorded. Despite the size of this event, no casualties have been reported, although the port of Severo-Kurilsk was inundated by a 4 m wave, causing Russian authorities to evacuate the town, and tsunami warnings were triggered across the Pacific.

The approximate location of the 30 July 2025 Kamchatka Earthquake. USGS.

The Kamchatka Peninsula lies on the eastern edge of the Okhotsk Plate, close to its margin with the Pacific and North American Plates. The Pacific Plate is being subducted along the margin, and as it does so it passes under the southern part of the Kamchatka Peninsula. This is not a smooth process, the rocks of the two plates continuously stick together then, as the pressure builds up, break apart again, causing Earthquakes.

Simple diagram showing the subduction of the Pacific Plate beneath the Okhotsk Plate along the Kuril Trench. Auburn University.

Earthquakes along subductive margins are particularly prone to causing tsunamis, since these often occur when the overlying plate has stuck to the underlying plate, being pulled out of shape by its movement.. Eventually the pressure builds up to far and the overlying plate snaps back, causing an Earthquake and a tsunami.

Simplified graphic showing tsunami generation along a convergent margin.NASA/JPL/CalTech.

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The Southern Delta Aquariid Meteor Shower.

The Southern Delta Aquariid Meteor Shower is visible between roughly 12 July and 23 August each year, and is expected to peak on 30 July this year, producing up to 25 meteors per hour. Best viewing this year is predicted to be between 2.00-3.00 am (this will be in local time wherever they are viewed from, as the time reflects the orientation of the planet to the rest of the Solar System) and dawn, when the radiant point of the shower (point from which the meteors appear to radiate), which is close to the star Delta Aquari (hence the name) will be highest in the sky. This year the peak of activity will fall slightly before the first quarter moon on 1 August, and the Moon will be in the constellation of Virgo, making it reasonably distant from Delta Aqaurius in the sky, and setting before midnight, so that it should not interfere with viewing of the peak of the meteor shower.

The radiant point of the Delta Aquariid Meteors. David Dickinson/Starry Night/Universe Today.

Meteor streams are thought to come from dust shed by comets as they come close to the Sun and their icy surfaces begin to evaporate away. Although the dust is separated from the comet, it continues to orbit the Sun on roughly the same orbital path, creating a visible meteor shower when the Earth crosses that path, and flecks of dust burn in the upper atmosphere, due to friction with the atmosphere.

The Earth passing through a stream of comet dust, resulting in a meteor shower. Not to scale. Astro Bob.

The Southern Delta Aquariids are thought to be caused by the Earth passing through the trail of Comet 96P/Machholz, where it encounters thousands of tiny dust particles shed from the comet as its icy surface is melted (strictly sublimated) by the heat of the Sun. 96P/Machholz is a short period, Jupiter Family Comet, crossing our orbit every 5.24 years, but the trail of particles shed by it forms a constant flow.

How the passage of the Earth through a meteor shower creates a radiant point from which they can be observed. In The Sky.

96P/Machholz was discovered by amateur astronomer Donald Machholz from Loma Peak in California; the name 96P/Machholz implies that it was discovered by Machholz and was the 96th periodic comet discovered (a periodic comet is a comet which orbits the Sun in less than 200 years). 

The orbit and current position of Comet 96P/Machholz. JPL Small Body Database.

96P/Machholz has an orbital period of 1929 days (5.28 years) and a highly eccentric orbit tilted at an angle of 58.5° to the plain of the Solar System, that brings it from 0.12 AU from the Sun at perihelion (12% of the distance between the Earth and the Sun, considerably inside  the orbit of Mercury, and closer to the Sun than any other known periodic comet); to 5.94 AU from the Sun at aphelion (5.94 times as far from the Sun as the Earth or slightly more than the distance at which Jupiter orbits). As a comet with a period of less than 20 years, 96P/Machholz is considered to be a Jupiter Family Comet.

Image of 96P/Machholz close to the sun taken by the Solar and Heliospheric Observatory on 8 January 2002. NASA/ESA/Solar and Heliospheric Observatory.

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Four Human deaths from Rabies outbreak in Timor-Leste in May & June 2025.

Four Human deaths from Rabies have been confirmed in Timor-Leste (formerly East Timor) between 17 May and 17 June 2025, according to a bulletin issued by the World Health Orgnization on 24 July 2024. All four had been bitten by Dogs infected by the disease, and suffered syptoms including hydrophobia, photophobia, aggressiveness, convulsions, and hallucinations, and all four were subsequently confirmed as Rabies infections by Reverse Transcription Polymerase Chain Reaction testing at the National Health Laboratory.

The first fatality was an adult male from Ermera Municipality, who was bitten by a Dog in March 2025, and sought medical help on 15 May, subsequently dying in a hospital two days later. The second fatality, another adult male, this time from Oecusse Municipality, who was bitten by a Dog in June 20242, and arrived at a regional hospital with symptoms on 27 May 2024, subsequently dying on 30 May. The third case was another adult male, this time from Bobonaro Municipality, who arrived at a medical centre on 12 June 2025, having been bitten by a Dog 2-3 months earlier. This parient subsequently died on 13 June. The final case was a female child from Bobonaro Municipality, who was taken into medical care on 12 June 2025, having been bitten by a Dog about two months earlier. This patient subsequently died on 17 June. Two further Rabies fatalities were reported in Oecusse Municipality in 2024.

The outbreak appears to have begun in Dogs in Oecusse Municipality in March 2024, since when 103 Dogs have died from the disease in Oecusse and Bobonaro Municipalities, as well as two Goats, one each in Oecusse and Bobonaro, and a Pig in Bobinaro. Oecusse Municipality forms an enclave within Indonesia's East Nusa Tenggara Province, where Rabies is considered to be endemic and Human fatalities are frequently reported, with Bobonaro shares a border with the province. Ermera Municipality lacks a border with Indonesia, but borders Bobonaro.

The island of Timor showing the regions covered by Timor-Leste and East Nusa Tenggara Province. Google Maps.

The rising number of Rabies deaths in Timor-Leste suggests the disease is spreading across the its borders with Indonesia, pobably via infected Dogs, and becoming established within the smaller nation. The World Health Organization recomends that this is addressed through a combination of Dog vaccinations and education to raise public awareness of the disease. 

Between March 2024 and 15 June 2025, 1445 dog scratches and bites were reported in Timor-Leste, 41% of which were considered to by Catagoy III exposures, which is to say exposures in which the skin is broken and saliva from an Animal has come into contact with this break. World Health Organization guidelines recomend that in such cases the wound should be washed immediately and the patient should be given  immediate vaccination and administration of rabies immunoglobulin/monoclonal antibodies. Of the 1445 known Catagory III exposures in Timor-Leste in 2024 and 2025, only 66% began this course of vaccination and antibody administration, and only 18% completed the course.

Rabies is caused by Viruses of the genus Lyssavirus, a member of the Rhabdoviridae Family of negative-sense single-stranded RNA Viruses, which also includes pathogens attacking Fish, Insects and Plants. Rabies is spread through the saliva of infected animals, and causes hydrophobia (fear of water),  anxiety, insomnia, confusion, agitation, abnormal behaviour, paranoia, terror, and hallucinations, followed by paralysis, coma and death in Humans. Many animals (notably Dogs) become extremely aggressive at this stage and will bite anything that comes near them, helping to spread the disease. 

Transmission electron microscope image with numerous rabies virions (small, dark grey, rodlike particles) and Negri bodies (the larger pathognomonic cellular inclusions of rabies infection). Centers for Disease Control and Prevention/Wikimedia Commons.

In Humans, the disease typically has a gestation period of about three months, during which time the disease can be treated by repeated vaccination and doses of human rabies immunoglobulin, though if treatment is not begun within ten days of infection it is less likely to be successful, and once the patient starts to develop symptoms the disease is almost invariably fatal. Any wound thought to have been caused by an infected animal should be washed thoroughly under running water for at least five minutes, before being treated with alcohol or iodine, and immediate medical attention sought.

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Pluto approaches opposition.

The Dwarf Planet Pluto will reach opposition (be directly on the opposite side of the Earth as the Sun) at 6.24 am GMT on Friday 25 July 2025. This means that it will be at its closest to the Earth this year, about 34.3AU (34.3 times the average distance between the Earth and the Sun, or about 3 639 716 200 km), and completely illuminated by the Sun. While it is not obvious to the naked eye observer, the planets have phases just like those of the Moon; being further from the Sun than the Earth, Pluto is 'full' when directly opposite the Sun, although with an apparent magnitude of only 15.0 it will take a reasonably good telescope to see Pluto at all, and it will only be visible as a star-like point to those that can see it. 

The relative positions of Earth and Pluto at 6.00 am on 25 July 2025. JPL Small Body Database.

Pluto was discovered in 1930 by Clyde Tombaugh, a young astronomer working at the Lowell Observatory in Arizona; its existence had been predicted as early as 1909, due to anomalies in the orbit of Neptune. At the time it was assumed that Pluto was a planet of some size, capable of disturbing the orbit of Neptune. Pluto spends part of its 248 earth year orbit inside the orbit of Neptune; this is not the same on every orbit, but alternates between a 20 and a 14 year stay.

The Dwarf Planet Pluto imaged by the New Horizons space probe in July 2015. NASA/JPL/Southwest Research Institute.

Pluto was downgraded from a planet to a dwarf planet by the International Astronomical Union in 2006, following the discovery of several similar small bodies in the Kuiper Belt beyond the orbit of Neptune. The term 'Dwarf Planet' is now used to designate objects large enough to form a roughly spherical shape under their own gravity, but no so massive as to have cleared the area around their orbit of all other objects. Pluto, Haumea, Makemake, and Eris were placed in this category, as was Ceres in the asteroid belt. Ceres had also been classified as a planet at the time of its discovery in 1801, as were a number of other asteroids until the mid-nineteenth century, when it became clear that asteroids were too abundant to be classed as planets.

The comparative sizes of Pluto, its largest moon, Charon, and the continental United States of America. Calvin Hamilton/Cornell University.

Pluto has an 247.7 year orbital period and an eccentric orbit tilted at an angle of 17.1° to the plane of the Solar System, which takes it from 29.6 AU from the Sun (i.e. 2960% of the average distance at which the Earth orbits the Sun) to 49.4 AU from the Sun (i.e. 4940% of the average distance at which the Earth orbits the Sun). As a body which spends most of its time outside the orbit of the planet Neptune it is classed as a Trans-Neptunian Object, even though it does come inside the orbit of Neptune for part of its orbital period.

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