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Sciences

Natural history - from animals to minerals, fossils to sea slugs. MV's scientists use the state's collections in important research.

The mighty mite part I

Author
by Patrick
Publish date
10 June 2015
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You may not realise it, but tiny mites are ubiquitous—about 50,000 species of mites have been described around the world, with an estimated half a million species yet to be described. They range in size from eriophyid mites at 125 micrometres in length, to velvet mites, the giants of the mite world, at 20mm long.

Red furry mite A Red Velvet Mite (Trombidiidae) from Victoria’s Alpine National Park.
Image: Patrick Honan
Source: Museum Victoria
 

They live in every terrestrial and aquatic habitat in the world, in your house and even on your body. About three quarters of humans have Eyelash Mites (Demodex species) living in their hair follicles and sebaceous pores around the eyelids, eyebrows and nose. Mites also live in the ears of our pets and all over our farm animals. We eat mites regularly, either raw or cooked with our vegetables, in quantities deemed acceptable by food regulators.

Red mite on leaf An erythraeid mite from Rowville, Victoria. These mites are commonly found wandering on eucalypts in bushland around Melbourne.
Image: Patrick Honan
Source: Museum Victoria
 

About 250 species of mites can affect human health, the most pervasive being the House Dust Mite (Dermatophagoides species) which feeds on dander (dead skin flakes). Its poo is the dust we ultimately breathe in. About 10% of people are allergic to this dust, and the average bed may be home to up to 10 million mites. Other mite species are also responsible for scabies and a great range of itches (grain itch, grocer’s itch, copra itch, straw itch, and so on).

But mites aren’t all bad by any means; in fact if it weren’t for them most ecosystems would collapse. They create and maintain soil, and many plant species support ‘mite houses’ (called domatia) on their leaves, providing homes for resident mites that in return keep the leaves clean. While good mites help the plants, the Two-spotted Mite (Tetranychus urticae) attacks and can destroy hundreds of different crops cultivated by humans, and is controlled in glasshouses around the world by the Predatory Mite (Phytoseiulus persimilis).

webbing on plant Two-spotted Mites (Tetranychus urticae) on an indoor plant. The webbing is produced by this species when their populations are high, to protect themselves and their eggs.
Image: Patrick Honan
Source: Museum Victoria
 

The Californian Mite (Paratarsotomus macropalpis) has recently overtaken the Australian Tiger Beetle (Megacephala australis) as the fastest animal on earth, at least in proportion to body size. Humans can run up to 10 bodylengths per second (BLS), the Cheetah up to 20 BLS and the previous record holder, the Tiger Beetle, can move at 171 BLS across the salt flats in north west Victoria. The Californian Mite moves at 322 BLS, the equivalent of a human being running at more than 2,000km per hour.

Mite under a log A trombidiid mite living under a log in wet rainforest at Wilsons Promontory, Victoria.
Image: Patrick Honan
Source: Museum Victoria
 

Mites are also the strongest animals on earth, again in proportion to size. The Tropical Moss Mite (Archegozetes longisetosus), which occurs in Australia and elsewhere, has holding forces in its claws equivalent to 1180 times its own weight, compared to the usual example of ants (50-100 times their own weight) and Rhinoceros Beetles (850 times). That’s the equivalent of an adult human male with a holding force of 90 tonnes.

The life cycles of mites are often quite bizarre. In one group of mites (Adactylidium species), the males die before or just after they are born, and the females are born pregnant and eat their own mothers alive from the inside out. Others live on or in a number of hosts, their body shape and number of legs varying throughout their lives.

Harvestman with red mite A red mite (Leptus species) piggybacking on a Harvestman (Opiliones) in the rainforests of Far North Queensland.
Image: Patrick Honan
Source: Museum Victoria
 

The word ‘mite’ originates from Old English, meaning ‘very small animal’. Mites are remarkably diverse in habitat and life cycle, easily the largest group of arachnids on earth. Although sometimes troublesome, we are dependent upon them in so many different ways, and if they weren’t so small they might take their rightful place in our psyche as some of the world’s most amazing animals. 

Junior Dino Experts

Author
by Kate C
Publish date
28 May 2015
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The very young are most susceptible to dino fever. In children, the symptoms are very clear: compulsive recitation of dinosaur names, a predilection for dinosaur motifs on every surface, a hyper-alert state anytime they 're near a fossil. In extreme cases, kids can reel off all the scientific inaccuracies in Jurassic Park. Fortunately, some kids never shake dino fever and they grow up to be palaeontologists.

Wayne Gerdtz curated two Melbourne Museum exhibitions that draw in lots of visitors: 600 Million Years: Victoria evolves and Dinosaur Walk. A chronic case himself, Wayne recalls a childhood filled with lurid dinosaur books. Since he grew up in remote country Victoria, his visits to the museum in Melbourne were infrequent and much anticipated. One prized souvenir from the 1970s exhibition Dinosaurs from China still hangs in his house. His palaeontological interests moved on to extinct mammals but dino fever still beats strongly in his heart.

 

Another trained palaeontologist, science educator Priscilla Gaff, thanks her Nana for fostering her interest in dinosaurs. From the age of 5 or 6, her Nana took her to the old museum every holidays. Cilla is still so afflicted by dino fever that she planned her upcoming overseas trip to include a visit to Mary Anning's old fossil-collecting grounds in Lyme Regis. (Anning herself hunted for fossils from a very young age and uncovered the first complete ichthyosaur skeleton when she was just 12, soon after her brother found the beast's skull.)

Mary Anning Portrait of Mary Anning with her dog Tray and the Golden Cap outcrop in the background. The painting is at the Natural History Museum, London.
Image: Credited to 'Mr. Grey'
Source: Public domain via Wikimedia
 

Now we seek the next generation of palaeontologists through the Junior Dino Expert Competition at Scienceworks. We are looking for children between the ages of 3–12 years of age who have a severe case of dino fever and a passion for sharing their dinosaur knowledge with others.  Applicants need to submit an application form and a creative response that demonstrates their love of dinosaurs. This could be a video, piece of writing, slide show, collage or anything else.

Junior Dino Expert Competition promo Junior Dino Expert Competition
Image: MV
Source: Museum Victoria
 

For details on how to enter, and a list of excellent prizes, visit the Junior Dino Expert Competition page. Be sure to have your entries in by Monday 8 June!

Links:

Tyrannosaurs – Meet the Family at Scienceworks

MV at sea

Author
by Tim O'Hara
Publish date
4 May 2015
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Dr Tim O'Hara is Senior Curator of Marine Invertebrates.

It is 3am, the night is jet black, the boat heaves with the swell, and a bunch of scientists and crew dressed in full wet-weather gear are silently standing, waiting on the back deck. There is always a sense of excitement as new samples are hauled in. What bizarre deep-sea creatures will be brought up? Perhaps this time we will see the enigmatic mushroom-shaped Dendrogramma, an animal (apparently) that has confounded all efforts at classification since its first collection by Museum Victoria in 1986. Or maybe the massive sea-lice that can devour a dead whale? Or just seafloor life in incredible abundance?

Large blue and white Investigator vessel The Marine National Facility research vessel Investigator at the CSIRO wharf in Hobart.
Image: Tim O'Hara
Source: Museum Victoria

Ship's crew using machinery on deck Deploying the Smith McIntyre grab.
Image: Tim O'Hara
Source: Museum Victoria
 

On Easter Tuesday, four science staff and students from Museum Victoria (Di Bray, Mel Mackenzie and Skip Woolley and I) joined scientists around Australia on a trial voyage of Australia’s brand new research vessel, the Investigator. The idea was to test out all the gear necessary for deep-sea exploration, from iron box-like dredges, used for over 200 years to collect samples, to the high tech cameras that bounce above the seabed, worked in real time from a joystick and a bank of computer monitors in the bowels of the ship, thousands of metres above. We went south of Hobart into the Southern Ocean, specifically to look at life on underwater sea mountains in the Huon one of the Commonwealth’s recently declared marine reserves.

People in the Investigator vessel lab The sorting lab: Skip, Di and Mel facing Karen Gowlett-Holmes of CSIRO.
Image: Tim O'Hara
Source: Museum Victoria

Big camera rig on ship deck The towed deep-sea camera.
Image: Tim O'Hara
Source: Museum Victoria
 

But I had another motive to joining this trip. Next year in November I will be chief scientist of a voyage from Brisbane to Hobart that will survey Australia’s abyssal sea-plain (4000 m below sea-level). So I really wanted to learn all I could about the capabilities of the vessel and think about best practice scientific procedures to ensure we get the most out of the expedition.

The Investigator, run by the Marine National Facility funded by the Commonwealth Government, is a large (94 m), elegant and efficient platform from which to do deep-sea research. Diesel electric engines keep the noise down and high tech stabilisers prevent much of the pitch, yaw and roll that can make life miserable on smaller boats.

People on ship deck The crew deploying gear off the stern deck.
Image: Tim O'Hara
Source: Museum Victoria

Ship crew deploying gear Preparing for the next catch: MV staff in canary yellow facing Mark Lewis of from CSIRO with Mark McGrouther of the Australian Museum looking on.
Image: Tim O'Hara
Source: Museum Victoria
 

My main memories of the trip: dark thundery night skies, albatrosses, friendly company and lots of carbs to eat. All too soon we steamed back to another sunny day in Hobart. We didn’t find Dendrogramma – maybe next time.

Happy birthday field guide apps!

Author
by Nicole K
Publish date
30 April 2015
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One year ago today we launched eight very special apps – field guides to the fauna of every state and territory in Australia. What makes these apps so special? They were produced collaboratively by Australia's seven leading natural history museums. 

The suite of 8 Field Guide to Australian Fauna apps. The suite of 8 Field Guide to Australian Fauna apps.
Source: Museum Victoria
 

Together the seven museums produced descriptions and sourced images for over 2100 animals from terrestrial, freshwater and marine environments. The result was a suite of pocket-sized identification guides, that could be used by everyone, everywhere – and they're free.

It's been a big year for the field guide apps. They have won two international awards, a Best of the Web award and a Muse award, as well as the Northern Territory Chief Minister's award for Excellence in the Public Sector.

The apps are also highly regarded by the app stores. All 8 apps appear in iTunes' Education Collections, which feature their hand-picked recommendations for "students, teachers, parents and lifelong learners". iTunes calls these apps "indispensable tools that will inspire students in every classroom".

MV Collection Manager, Katie Smith, using the Field Guide app. MV Collection Manager, Katie Smith, using the Field Guide app.
Source: Museum Victoria
 

Over the past year, the apps have been used by the museums in school holiday activities, education programs, teacher training, community outreach and biological surveys. But we're most excited about how the public are using them – to identify animals and to learn more about Australia's amazing wildlife.

Students using Museum Victoria's app in the Forest Gallery at Melbourne Museum. Students using Museum Victoria's app in the Forest Gallery at Melbourne Museum.
Image: Mirah Lambert
Source: Museum Victoria
 

The apps have received glowing praise from their users and, since the launch, have been downloaded over 78,000 times. We're absolutely thrilled that the apps have been so well received and look forward to what the next year will bring.

The National Field Guide Apps Project was funded by an Inspiring Australia Unlocking Australia's Potential Grant. The project was a 2-year collaboration between: 

Transcribing field diaries

Author
by Nicole K
Publish date
19 March 2015
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Deep in Museum Victoria’s archives lie boxes of notebooks. Notebooks that contain a significant part of our museum’s history. They are the field diaries of our past curators and collection managers, produced on scientific expeditions to explore, research and discover the natural history of Australia (and beyond).

Field diaries from Museum Victoria's collection Field diaries from Museum Victoria's collection
Source: Museum Victoria
 

These field diaries are of great interest to both scientists and historians. They are filled with invaluable data, providing insights into past species’ abundance and distribution, as well as personal descriptions of the trials and wonders experienced on historic expeditions.

A photograph from Graham Brown's field diary: Mt Rufus, Tasmania (1949). A photograph from Graham Brown's field diary: Mt Rufus, Tasmania (1949).
Image: Graham Brown
Source: Museum Victoria
 

Despite the fascinating information contained within the diaries (and the interest in them), they are relatively inaccessible. They were handwritten, often in less-than-favourable conditions (picture a scientist, crouched in the bush, notebook balanced on knee).

Sketch from Allan McEvey's field journal of his expedition to Macquarie Island, 1957. Excerpt from Allan McEvey's field journal of his expedition to Macquarie Island, 1957.
Image: Allan McEvey
Source: Museum Victoria
 

We have therefore started a crowd-sourcing project to transcribe the field diaries in our collection. The pages of each diary are carefully digitised and then uploaded into DigiVol the Atlas of Living Australia’s volunteer transcription portal that was developed in collaboration with the Australian Museum. Once transcribed, the text in the diaries will be searchable. We can create lists of the species mentioned and use this information to better understand and conserve our precious biodiversity.

Our most recent transcription project is Allan McEvey's field diary of his expedition to Macquarie Island in 1957. Museum Victoria's Curator of Birds from 1955, McEvey had a passion for scientific illustration and his field diaries are filled with sketches of birds and other wildlife.

Sketches of Black-browed Albatross, <i>Diomedea melanophris</i>, from Allan McEvey's field journal of his expedition to Macquarie Island, 1957. Sketches of Black-browed Albatross, Diomedea melanophris, from Allan McEvey's field journal of his expedition to Macquarie Island, 1957.
Image: Allan McEvey
Source: Museum Victoria
 

The original diaries, along with their transcriptions, will eventually be available online via the Biodiversity Heritage Library (BHL), the world's largest online repository of biodiversity literature and archival materials.

The Australian component of BHL is managed by Museum Victoria and funded by the Atlas of Living Australia. The project has allowed us to digitise over 500 rare books, historic journals and archival field diaries. This represents over 12000 pages of Australia’s biological heritage that was previously hidden away in library archives.

Interested in becoming a transcription volunteer?

If you would like to help us unlock the observations in our historic field diaries, more information is available on the DigiVol website.

Dawn reaches Ceres

Author
by Tanya Hill
Publish date
5 March 2015
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When NASA’s Dawn spacecraft is captured into orbit around the dwarf planet Ceres on Friday, March 6, there will be no fanfare in mission control. In fact, the spacecraft won’t even be in radio contact. There’s no need, because Dawn’s path is set – this is a spacecraft unlike any other.

What makes Dawn unique is its ion propulsion system, which gives the spacecraft incredible manoeuvrability. Instead of using large bursts of thrust to get where it’s going, Dawn takes the slow and steady approach. Its ion engine delivers a tiny but continuous thrust that can last for days or weeks at a time.

Over the last two-and-a-half years, Dawn has been slowly reshaping its trajectory to bring it near Ceres and, most importantly, to match the dwarf planet’s speed – Ceres travels around the sun at nearly 64,000 kilometres per hour.

For other planetary missions, entering orbit is make or break. It’s an intense moment that hopefully ends in jubilant celebration when all goes as planned and the spacecraft momentously falls into orbit. But Dawn’s slow approach means that it is now right on course to guarantee capture by Ceres’ gravity.

Dawn is captured by Ceres' gravity The spacecraft’s approach trajectory with the white circles spaced at intervals of one day. This indicates the spacecraft’s speed – the closer the circles, the more slowly Dawn is moving.
Source: NASA/JPL
 

Come Friday, if the spacecraft’s propulsion were to be switched off it would remain under Ceres’ influence but would travel around the dwarf planet in a highly elliptical orbit. So over the next few weeks, Dawn will use its ion thrusters, together with Ceres’ gravity, to slowly draw it into a circular orbit – the first of four such orbital positions around the dwarf planet.

Not for the first time

Ceres is the second object that Dawn has orbited. Between July 2011 and September 2012, Dawn was in orbit around Vesta, which, like Ceres, resides in the asteroid belt located between Mars and Jupiter.

This marks the first time that one spacecraft has been able to orbit two different planetary objects. And it’s only possible because of Dawn’s ion engine.

A spacecraft powered in the usual way, using chemical propellant, would require ridiculous amounts of fuel to carry out such a mission. And even if it was possible for a spacecraft to carry that much fuel on-board, the cost of the mission would be astronomical.

Dawn's path to Ceres Dawn was launched in September 2007 and has taken the slow and steady approach to visit Vesta and now Ceres.
Source: NASA/JPL
 

At Ceres, Dawn will eventually travel in a polar orbit, travelling above the north and south poles. As it moves from north to south it will travel over the daytime side of the planet, and then during the second half of its orbit it will fly above Ceres' night side.

In its first orbital position, at a height of 13,500km, it will take 15 days for Dawn to complete one orbit. Since the planet takes only nine hours to rotate on its axis, this will allow Dawn to make a good map of the dwarf planet’s surface.

Throughout its 15-month mission, Dawn will vary its orbit three times, each one descending closer to the planet at heights of 4,400 km, 1,470 km and 375 km. To change orbits it will move through a complex series of spiral trajectories.

The descent to its lowest orbit will take two months and, during that time, Dawn will complete 160 revolutions as it constantly reorientates itself to ensure that one of its ion beams is thrusting in the right direction to continue its slow spiral descent.

Dawn's spiral descent Two months of downward spirals are needed to move Dawn into its lowest orbit - from the High Altitude Mapping Orbit (HAMO) to the Low Altitude Mapping Orbit (LAMO).
Source: NASA/JPL
 

Better than Star Wars

Ion propulsion systems, like the one that powers the Dawn spacecraft, have long been considered the next big thing for space exploration. In fact, they seemed so futuristic that they appeared in the Star Wars movies, powering Darth Vader’s TIE fighters or Twin Ion Engine fighters.

Science fiction to science fact The TIE fighters in Star Wars had twin ion engines, but Dawn does one better, with three ion engines.
Source: NASA/JPL
 

Ion engines were first used by NASA on Deep Space 1, which flew past the asteroid 9969 Braille in 1999 and comet Borrelly in 2001.

The Japanese Aerospace Exploration Agency (JAXA) has successfully used ion engines on its Hayabusa asteroid missions, the second of which was launched in December last year.

The Dawn spacecraft is fitted with three ion engines, although only one engine is used at any one time. And true to what we expect from science fiction, the spacecraft does emit a blue-green glow. This is a result of its xenon fuel.

The inner workings of an ion propulsion system. The inner workings of an ion propulsion system.
Source: NASA
 

Positively-charged xenon ions pass through two electrically charged grids. This accelerates the tiny ions and they shoot out of the engine at 144,000 kilometres per hour, providing the thrust to propel the spacecraft in the opposite direction.

Ion engines are around ten times more efficient than chemical rockets because the ions are ejected at roughly ten times the speed that a propellant is expelled by a rocket. The acceleration, however, is much slower.

It would take Dawn around four days to accelerate from 0 to 100 kilometres per hour but the trade off is that in doing so, it would only use 450grams (or just one pound) of fuel.

Why Vesta and Ceres?

Of course, the reason the technology is so marvellous is because it enables such fantastic science – the exploration of the two most massive objects in the asteroid belt, Ceres and Vesta.

The dwarf planet Ceres New images of Ceres, taken February 19 at a distance of 46,000km, show a mysterious double bright spot.
Source: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
 

Don’t let their location fool you – these are not space rocks like typical asteroids. They are big worlds and, like Earth and the other terrestrial planets, Ceres and Vesta have a layered structure.

Vesta has an iron-rich core, a silicate mantle and a crust made of basalt. While Ceres is thought to have a rocky core, an ice mantle and a dusty surface.

The ice mantle is particularly interesting. It’s thought that around 30% of Ceres’ mass may come from water and potentially some fraction of that could be liquid water. Just last year, the Herschel Space Observatory made detections of what appear to be plumes of water vapour escaping from slightly warmer regions on Ceres.

The Dawn mission will continue until June 2016 and the latest images will be regularly posted here, while the Dawn mission blog is a great way to keep up-to-date on everything that happens.

Dawn of the Solar System

The space mission was called Dawn because if we think of Ceres and Vesta as protoplanets, then by better understanding these objects, we will gain insight into the early history of our solar system.

Vesta and Ceres size comparisons Ceres and Vesta more closely reflect half-formed planets than space rocks like asteroids.
Source: NASA
 

The planets of our solar system formed by a method of accretion. Starting out as specks of dust that collided and stuck together, they then grew bigger and formed rocks until eventually they were large enough to draw in enough material to form planets.

Vesta and Ceres seemed to have halted mid-way through this process. This is most likely due to the formation of Jupiter. Its gravity may have prevented objects in the asteroid belt from coming together to finish off the planet building.

As a result, Vesta and Ceres provide a unique opportunity for understanding the early formation of the planets, because they came so close to becoming planets themselves.

The early solar system The early solar system was born out of a dusty disc encircling the sun.
Source: William Hartmann. Courtesy of UCLA
 

The ConversationThis article was originally published on The Conversation. Read the original article.

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