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Melbourne Museum

Melbourne Museum explores life in Victoria, from our natural environment to our culture and history. Located in Carlton Gardens, the building houses a permanent collection in eight galleries, including one just for children.

Bugs within bugs, part 2

Author
by Patrick
Publish date
7 May 2014
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Like any group of animals (or people), populations of bugs are susceptible to disease, pathogens and parasites. At Live Exhibits we keep our populations free from parasites, but sometimes new bugs from the wild turn out to be Trojan horses filled with unwanted guests.

Tachinid fly pupae Tachinid fly pupae, newly emerged from the abdomen of a Rainforest Mantid (Heirodula majuscula), collected from Cairns, North Queensland. These flies are always fatal to the mantid.
Image: Patrick Honan
Source: Museum Victoria
 

The parasites not only kill the bugs themselves, but could get into captive populations and cause havoc. Most of them are easily controlled once identified, and occasionally we can even operate to remove the parasite and allow the host to lead a long and fruitful life.

parasitic wasp larva A parasitic wasp larva being successfully removed from the abdomen of a living Olive-green Katydid (Austrosalomona falcata) collected from the wild.
Image: Alan Henderson
Source: Museum Victoria
 

But often this is not so successful and the first sign of something wrong is the presence of two different species within an enclosure rather than just one. When you get to recognise the signs of parasitism, it’s often difficult to find individual insects in the wild that are not parasitised.

tachinid fly larva A tachinid fly larva emerges from a wild-caught Robust Fan-winged Katydid (Psacadonotus robustus). The only indication of infection was the abnormally large abdomen of the male katydid.
Image: Melvin Patinathan
Source: Museum Victoria
 

One of the most insidious is the Gordian worm, named after the Gordian knot of mythology. These are long, hair-like worms up to half a metre long which begin their lives in freshwater streams attacking aquatic insects. When the aquatic host, such as a dragonfly or mayfly nymph emerges into adulthood, it leaves the stream and is caught and eaten by a spider, cricket or beetle. The worm grows within its new host, filling up the entire body cavity until the host is 95 per cent Gordian worm.

Gordian worm emerging A Gordian worm emerging from an Olive-green Katydid (Austrosalomona falcata).
Image: Alan Henderson
Source: Minibeast Wildlife
 

When fully fed, the worm causes its host to become thirsty to encourage it to seek out water where the worm emerges and continues its life cycle, laying more than 10 million eggs. Earlier this year Live Exhibits staff collected eight huntsmans near Cape Tribulation, North Queensland, five of which produced Gordian worms over the next few weeks.

 

Video: A newly emerged Gordian worm and its host, Beregama cordata, from the #liveexhibits takeover of the Museum Victoria Instagram account.
Source: Patrick Honan/Museum Victoria

The relationship between parasites and their hosts is an evolutionary arms race – as hosts come up with more effective defences, the parasites evolve techniques such as behavioural modification to overcome them. This fascinatingly gruesome relationship can be the stuff of nightmares; inspiration for everything from zombies to the film Alien, proving that science is stranger than science fiction.

This is the second in pair of posts about parasites. Don't miss Bugs within bugs, part 1

References:

Askew, R.R., 1971, Parasitic Insects, American Elsevier, USA, 316pp

CSIRO, 1990, Insects of Australia, Volume 1 & 2, Melbourne University Press, Melbourne, 1137pp

Gauld, I.D., 1984, An Introduction to the Ichneumonidae of Australia, British Museum (Natural History), UK, 413pp

Matthews, E.G. & Kitching, R.L., 1984, Insect Ecology (second edition), University of Queensland Press, Brisbane, 211pp

Small(er) is beautiful

Author
by Wayne
Publish date
4 May 2014
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When we think of Ice Age land animals, we often add the word ‘giants’; certainly many of the mammals of the Pleistocene were very large  – including many here in Australia. In a previous post, we’ve defined megafauna, and looked at a few Australian examples from the Quaternary. There is a different way of looking at this, though – rather than thinking of the Ice Age megafauna as ‘ancient giants’, it is equally valid to study modern-day animals from the perspective of them being dwarf or pygmy forms of their Ice Age relatives.

The phenomenon of dwarfism in post- Ice Age mammals changes the question from “why were they so big back then?” to “why are they so small now?”

Before we go any further, we should keep in mind that not everything was giant-sized in the Pleistocene; there were many ‘normal’ sized animals (by today’s standards) living happily alongside the big guys – it was just that the big ones were really big. It’s also important to remember that many of the ‘pygmy’ forms lived alongside their ‘giant’ relatives, rather than replaced them – there’s no such thing as a succession plan in evolution.

Having said this, here are a few examples of ‘dwarf megafauna’ alive today that had gigantic skeletons in their closets.

An example of ‘miniature giant’ is the modern day Eastern Grey Kangaroo Macropus giganteus; certainly large for an Australian land mammal, but 40-something thousand years ago it was overshadowed by its immense relative Macropus titan by 30%.

  skull of Macropus titan Skull of the Giant Grey Kangaroo Macropus titan. The ‘giant’ part is correct, but the ‘grey’ part is speculative; the colour of the Giant ‘roo is unknown…
Image: Tim Holland
Source: Museum Victoria
 

Similarly, the largest living Goanna, the Perentie Varanus giganteus, impresses with its size….but is smallfry against the immense extinct evolutionary ‘cousin’ Varanus “Megalania” priscus, – estimated at over twice (some have said thrice) the size.  

­­This also holds true on the Tasmanian Devil Sarcophilus laniarus, which had an over-sized, mainland-resident relative at least 15% larger than its living subspecies. All of these animals are at least in the same genus as their megafaunal relatives, in some cases they are subspecies of their modern-day pygmy forms.

Tasmanian devil skull Skull of the Giant Mainland (rather than Tasmanian) Devil Sarcophilus laniarus
Image: Tim Holland
Source: Museum Victoria
 

So, whilst it is true to say that in broad terms, there was an extinction event about 45, 000 years ago that led to the ‘end of the Megafauna’, this event was complex - there were other patterns at play that saw downsizing as a successful survival strategy.

Obviously many Australian megafauna taxa became entirely extinct as well, inconveniently leaving no close descendants or relatives, but their story is for yet another blog…

Taking nature to the nation

Author
by Nicole K
Publish date
1 May 2014
Comments
Comments (2)

In 2011 Museum Victoria produced our first Field Guide app: the MV Field Guide to Victorian Fauna.

The app has since been downloaded by over 85,000 people and gets great reviews. But there has been a repeated request – a request from people who don't live in Victoria.

Where are the apps for the other Australian states and territories?

This wasn't something we could address on our own. To make apps for the other states and territories, we needed the shared expertise of natural history museums around the country.

In 2012, Museum Victoria was successful in applying for an Inspiring Australia Unlocking Australia's Potential Grant to produce seven new Field Guide apps in collaboration with:

  • Australian Museum
  • Museum and Art Gallery of the Northern Territory
  • Queensland Museum
  • South Australian Museum
  • Tasmanian Museum and Art Gallery
  • Western Australian Museum


For the past two years, scientists around Australia have been writing species descriptions, sourcing images and we have been tweaking the code. We have also worked with colleagues from the Atlas of Living Australia to source taxonomic names, conservation status and recorded observations of each species.

We are very excited to announce that the products of this nation-wide collaborative project are now available.

Field Guide to ACT Fauna app (iPhone & iPad) Field Guide to ACT Fauna app (iPhone & iPad)
Source: Museum Victoria
 

There are now eight apps – Field Guides to the Fauna of New South Wales, Northern Territory, Queensland, South Australia, Tasmania, Western Australia and the ACT – as well as a new version of the original Field Guide to Victorian Fauna.

Collectively the apps contain 2105 species, 7281 images and 270 audio files.

They are available for both Apple and Android devices. And are all absolutely FREE.

We hope you enjoy them!

Links to the App Store and Google Play can be found via our National Field Guide Apps webpage.

Field Guide to Victorian Fauna (Android) Field Guide to Victorian Fauna (Android)
Source: Museum Victoria
 

Why we can't give a stuff

Author
by Alice
Publish date
29 April 2014
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Comments (1)

The Discovery Centre receives heaps of enquiries from budding enthusiasts eager to learn the art of taxidermy – it’s no surprise because Museum Victoria holds the largest collection of taxidermy mounts in the state.

behind the scenes Rows of taxidermy mounts hidden behind the scenes of the Melbourne Museum.
Image: Alice Gibbons
Source: Museum Victoria
 

Taxidermy is but one of many tasks performed by the multi-talented members of our preparation department. The preparators work purely on museum projects, combining skills in taxidermy, moulding, casting and model-making to enhance the state’s collections and research.

reptile moulds Reptile moulds and casts hand made by the preparation department.
Image: Alice Gibbons
Source: Museum Victoria

 

Seal model Sculpting and modelling a seal for permanent display.
Image: Alice Gibbons
Source: Museum Victoria
 

Only a fraction of the work that the preparation department performs makes its way to the public displays, with the majority of their work residing behind the scenes. Most animals coming into the museum join the research collections and don’t need to be prepared as life-like mounts; 90 per cent of the specimens prepared at the museum have data and tissue samples collected and are preserved as study skins and skeletons. These specimens become priceless tools in assisting scientists identify and compare new species, better understand the evolution of species over time, and research how we can conserve our fauna into the future.

Study skins Study skins used in the research collection.
Image: Alice Gibbons
Source: Museum Victoria
 

Skeletal remains Skeletons prepared for the research collection with the assistance of dermestid beetles.
Image: Alice Gibbons
Source: Museum Victoria
 

Due to the busy workload of our preparators, we are unable to provide personal advice to individuals about taxidermy. We are, however, bringing out our experts for the next Smart Bar to focus on the history, methods and tools of the craft. This Thursday 1 May, from 6-9pm our experts will explore the inside story of taxidermy with pop up talks and demonstrations.

Koala moulding Tools and measurements used in making a koala cast.
Image: Alice Gibbons
Source: Museum Victoria
 

exhibition maitenance Ongoing maintenance of exhibition material such as this interactive component from Think Ahead is a large part of the preparation departments workload.
Image: Alice Gibbons
Source: Museum Victoria
 

For those unable to attend, there is plenty of information available online through supply websites, online tutorials and forums. Commercial taxidermists can also be found in the Yellow Pages, and you may be lucky enough to find one who is willing to discuss their tricks of the trade. Formal tutelage in taxidermy is almost non-existent in Australia but getting involved in online forums and clubs is a great starting point to meet likeminded people and gain expert advice. Most of our preparators started out reading taxidermy books for beginners, many of which can still be found in local libraries.

Keep in mind that in Australia there are strict licencing protocols surrounding practicing taxidermy on native animals. For more information visit the Department of Environment and Primary Industries website.

Links:

Smart Bar: Stuffed

So many specimens

Bugs within bugs, part 1

Author
by Patrick
Publish date
28 April 2014
Comments
Comments (1)

To support our collection of almost 100 invertebrate species on display at Melbourne Museum, Live Exhibits staff must occasionally collect bugs from the wild, and some of these can hold unwanted surprises inside.

Chalcid w A Chalcid wasp, newly emerged from the cocoon of its host caterpillar.
Image: Patrick Honan
Source: Museum Victorai
 

At least one in every ten insect species is a parasite on other insects. In Australia this adds up to several tens of thousands of parasitic insect species, all living their lives on the outside or, more commonly the inside, of other insects. Most of these parasites are wasps and flies, and most of their hosts are butterflies, moths and beetles.

Tachinid fly eggs on beetle Tachinid fly eggs on the outside of a doomed Leaf Beetle larva (Paropsis species).
Image: Patrick Honan
Source: Museum Victoria
 

Parasitic insects usually lay their eggs directly onto or into the body of their host, but may lay eggs on a food plant in the hope that they will later be ingested by a potential host. Once inside, the parasitic larva consumes the host’s internal tissues while the host continues to go about its business. The parasite usually avoids the vital organs until the last minute – then polishes these off and finally kills its host.

Aphid ‘mummies’ Aphid ‘mummies’ – aphids that have been parasitised and glued to the leaf by Braconid wasps. When fully developed, the wasps will cut a perfectly circular hole in the back and emerge as adults.
Image: Patrick Honan
Source: Museum Victoria
 

Parasitic wasps are able to find their hosts no matter where they might hide. In order to lay eggs on its host – Sirex Wood Wasp (Sirex noctilio) – Megarhyssa (Megarhyssa nortoni) can drill through 9cm of solid wood with its ovipositor (egg-laying organ). Megarhyssa females find their hosts using infrared detectors on their antennae; the outer bark of a tree is 0.5oC warmer where a larva lies underneath.

female Megarhyssa A female Megarhyssa (Megarhyssa nortoni) drills through a pine tree to deposit an egg on the Sirex Wood Wasp within.
Image: Patrick Honan
Source: Museum Victoria
 

A parasitic wasp will sometimes inject venom that paralyses the host but keeps it alive, allowing the wasp to hide it away for its offspring as a sort of living larder. A large wasp dragging a larger, paralysed, huntsman across open ground is a familiar sight during summer.

Pompilid wasp drags a huntsman A Pompilid wasp drags a huntsman (Isopeda species) from its hiding place under bark, before paralysing it and inserting an egg.
Image: Patrick Honan
Source: Museum Victoria
 

A caterpillar can sometimes dislodge a parasite’s eggs with its mandibles, but wasps usually lay their eggs just behind the caterpillar’s head where they can’t be reached. Many hosts are able to ‘encapsulate’ a parasite already inside their bodies, localising its damage and starving it of oxygen. When more than one parasite is laid inside a host, the larvae fight to the death within the host’s body for the rights to its organs.

wasp cocoons inside the empty shell of a Cabbage White Butterfly caterpillar Thousands of parasitic wasp cocoons inside the empty shell of a Cabbage White Butterfly caterpillar (Pieris rapae). Each cocoon will soon produce a tiny wasp that flies off to find other caterpillars to parasitise.
Image: Patrick Honan
Source: Museum Victoria
 

Parasites are themselves subject to attack from hyperparasites, insects that lay eggs inside an already-occupied host. The emerging larva seeks out the parasite in residence and burrows into its body. These in turn may be parasitised by superhyperparasites, and so on.

“Great fleas have little fleas upon their backs to bite 'em,

And little fleas have lesser fleas, and so ad infinitum…”

Augustus de Morgan (after Jonathan Swift)

Cork Colosseum x-ray

Author
by Kate C
Publish date
17 April 2014
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An x-ray machine usually employed for mammography examined an unconventional patient earlier this year: a model of the Colosseum made from cork around 1800. Thanks to generous assistance from Lake Imaging in North Melbourne, object conservator Sarah Babister now has a view inside one of our most curious objects.

Four people discuss photograph Conservators Sarah and Dani show radiographers Jeff and Ghazia a photo of the Colosseum model.
Source: Museum Victoria

cork Colosseum model The facade of the Colosseum model. (HT 24386)
Source: Museum Victoria
 

Radiographer Ghazia adjusted the settings of the mammography machine to accomodate this unusual material—cork is much less dense than human tissue—and produced wonderfully clear and informative images of several pieces of the Colosseum.

Woman with x-ray machine Ghazia placing a piece of the Colosseum on the mammography machine.
Source: Museum Victoria

Woman with computer Ghazia adjusting the levels of the x-ray to best show the hidden structure within the cork Colosseum.
Source: Museum Victoria
 

We think that our Colosseum was built by English model-maker Richard Du Bourg (or Dubourg), but in the absence of a signature, Sarah is looking for characteristic materials and construction techniques that could confirm its maker. Further research by historian (and the museum’s Head of Humanities) Richard Gillespie and genealogist Neil Gill is fleshing out the intriguing story of Du Bourg and his models; Richard recently visited similar objects in overseas collections for comparison. Sarah and Richard will present a talk about the model and its story next month as a part of the History, Cultures and Collections seminar series.

From 1775 to 1819, Du Bourg’s models of classical ruins were the height of fashion and his a well-known London exhibition. “He’s a fascinating character,” says Sarah. Notoriously, his working model of Vesuvius destroyed an entire exhibition when its eruption set fire to all the other models on display. “He lived until he was in his early 90s and even though he’d been very famous he was living in poverty.”

Sarah explains that cork models “were really popular at a certain time and were kept as tools to teach students. Then they fell out of fashion and a lot of them were disposed of.” This may explain Du Bourg’s impoverished old age, and is the reason why the museum has this model at all – in 1929 it was sent from the Science Museum in London to the Industrial and Technological Museum in Melbourne.

cork Colosseum detail Sarah holding a large piece of the Colosseum model.
Source: Museum Victoria
 

The model is over a metre wide and in poor condition. The base it sits on is cracked and the gesso applied to the perimeter is flaking, and several sections of wall have broken off. These broken sections are a mixed blessing, since without them there could be no x-rays, which reveal the lead pencil marking lines, and pins and nails used to hold the pieces of cork together. This information may help confirm whether Du Bourg made the model, but will also help Sarah reattach the broken pieces.

X-ray image of a piece of the cork Colosseum X-ray image of a piece of the cork Colosseum. The metal pins, and decorative carvings covered in lead paint, appear white.
Image: Lake Imaging
Source: Museum Victoria
 

“Most of the pieces are there so the model would be virtually complete with the exception of a few small columns which might need to be replicated,” she says. “I’d love to put it back together so it can be viewed how it should be viewed because it’s such an amazing object. The level of detail in the carving is wonderful, and cork lends itself so well to representing that ruinous state.”

To learn what the x-rays revealed, come along to Richard and Sarah's free seminar on 14 May, titled For the Nobility, Gentry & Curious in General: Richard Du Bourg’s Classical Exhibition, 1775-1819.

Links:

Cork Colosseum model on Collections Online

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Updates on what's happening at Melbourne Museum, the Immigration Museum, Scienceworks, the Royal Exhibition Building, and beyond.

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