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DISPLAYING POSTS FROM: May 2011 (17)

Aboriginal artefact stolen

Author
by Kate C
Publish date
9 May 2011
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Comments (1)

In the early hours of Saturday 7 May, an intruder stole an important cultural object from Melbourne Museum. Police are investigating the theft, and Museum Victoria appeals for its safe return.

Central Australian spearthrower Central Australian spearthrower stolen from Melbourne Museum.
Source: Museum Victoria
 

The item is a spearthrower from Central Australia. It is approximately 80cm long and is made from mulga wood. Carved into the item is a series of circles and lines depicting waterholes, creeks and claypans in Pintupi country.

If you have any information about the stolen object, please contact Melbourne Museum or the police.

Publishing possums

Author
by Kate C
Publish date
9 May 2011
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Nick Alexander from CSIRO Publishing visited the MV Library last week in search of gliding mammals. He’s working on the production of an upcoming book by Stephen Jackson called Gliding Mammals of the World.

The book will cover certain groups of mammals - squirrels, possums and lemurs - that have evolved traits for soaring between trees, such as extra folds of skin along the sides of their bodies. Victorian gliding mammals include Squirrel Gliders, Sugar Gliders and Yellow-bellied Gliders.

Nick Alexander Nick Alexander taking photos of natural history illustrations in the MV Library.
Source: Museum Victoria
 

In Gliding Mammals of the World, 19th century artworks from our rare books will accompany an introduction to the historical context of gliding mammal studies. Some of the early European natural history illustrations are, in Nick’s words, 'rather fanciful' but the new book will be beautifully illustrated by Peter Schouten who is renowned for his accurate and naturalistic wildlife illustrations.

You can look forward to the publication of Gliding Mammals of the World later this year.

Links:

CSIRO Publishing

Stephen Jackson

Peter Schouten's site 

I belong - do you?

Author
by Jareen
Publish date
5 May 2011
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When do you feel like you belong? This question is central to the new exhibition Identity: yours, mine, ours that opens at the Immigration Museum on 11 May. We took this question to the streets, setting up an open photo shoot in Little Collins St at the end of March. These photos are now in the Identity at the Immigration Museum group on Flickr and the overview video below.

 

If you’re on Twitter, we'd love to hear your #ibelong story, too. We want you to tell us “I feel #ibelong when...’  We'll put selected tweets up on a screen at the exhibition launch and during the opening weeks of the exhibition, we’ll be giving away tickets for some of the best #ibelong tweets. You can also follow the #ibelong tweets via the Immigration Museum Twitter account.

Links:

Identity: yours, mine, ours website

So many spiders

Author
by Kate C
Publish date
4 May 2011
Comments
Comments (9)

Have you noticed the unusually high population of golden orb-weaving spiders (Nephila edulis) in Melbourne this year? They're usually very rare this far south but I’ve spotted dozens of them in the inner-city suburbs over recent months. Our online visitors have too; in the past three months, we’ve received over 50 comments on this Question of the Week about these spectacular spiders.

Discovery Centre gets a lot of queries about spiders and whether they’re dangerous, often after they’ve received a lethal dose of insect spray, so it’s delightful to see that most of the recent comments simply marvel at the size, beauty and architectural skills of these spiders. Lots of people have told us they are quite fond of their backyard Nephila and some have even given them names! We’ve heard about Bertha, Gloria, Holly, and, I confess, I’ve named the one that lives near me Nefertiti.

Nephila edulis Nefertiti the large female Nephila edulis.
Source: Museum Victoria
 

Because people are so interested, I thought I’d dig up a bit more about Nephila edulis. They are more often found in northern Victoria, NSW and QLD where there has been a bumper spider season, too. Professor Mark Elgar from the University of Melbourne has studied these spiders for many years, travelling to Euroa each spring to collect specimens for behavioural studies. He recently commented in the Shepparton News that high summer rainfall “has provided a lot more food for flying insects, which become food for spiders. They really are much more abundant than I've seen for a long time and next year we'll see the same thing.”

Nefertiti sits in her large golden web all day, unlike the nocturnal and more common Garden Orb-weaving Spider (Eriophora sp.), which tears down and rebuild its web almost daily. Nefertiti leaves her web up until it’s so ratty that it needs to be repaired and her home is adorned with a rather gruesome array of dead insects. Professor Elgar and his colleagues showed that this vertical band of detris is a stockpile of food but also serves another intriguing function; it attracts more food. The spiders deliberately incorporate bits of rotting vegetation to make their larders irresistable to flies.

Nephila edulis The underside of a large mature female Nephila edulis on her web. In the background is her egg sac and hanging in her web is a detrius band of dead insects.
Source: Museum Victoria
 

Another fascinating aspect of Nephila biology is the difference in size between males and females. While females are generally much larger than the males, within males there is a big variation in size. Professor Elgar and colleagues investigate how this has evolved. It’s a complex question with no definite answers and lots of factors to consider.

Male and Female Golden Orb spider A pair of golden orb-weaving spiders illustrating the difference in size between males and females. The tiny male is on the left while the large female, feeding on a moth, is on the right.
Image: Bill & Mark Bell
Source: Used under Creative Commons license (CC BY-NC-SA 2.0) from Bill & Mark Bell
 

Male N. edulis have two strategies when it comes to approaching a female. The risk of being mistaken for her lunch is pretty high so it pays to be careful. One tactic is to crawl onto the web on the same side as the female, while another is to approach from the opposite side and cut a hole in the web. Small males are more common than large males and they tend to use the first strategy. They also mate for longer and father more of the female’s offspring. However there are costs to being small, too: smaller males are more often eaten by females than large males. Furthermore, if there are a number of males loitering around the edge of a female’s web, large males beat small males in the battle to reach the female.

I don’t know if she was courted by a large or small male (or both - these spiders mate several times), but Nefertiti has laid a clutch of eggs in a golden silk sac. In spring her eggs will hatch and her babies will disperse on the wind to start the whole cycle again. Keep an eye out for them later in the year! Meanwhile, if you’d like to see a golden orb-weaver up close, visit the Orb Wall in Bugs Alive! at Melbourne Museum.

egg sac of Nephila edulis The golden silk egg sac of Nephila edulis.
Source: Museum Victoria
 

Links:

Victorian Spiders

B. T. Bjorkman-Chiswell, M. M. Kulinski, R. L. Muscat, K. A. Nguyen, B. A. Norton, M. R.E. Symonds, G. E. Westhorpe and M. A. Elgar. 2004. Web-building spiders attract prey by storing decaying matter. Naturwissenschaften 91:245-248

J. M. Schneider, M. E. Herberstein,  F. C. de Crespigny, S. Ramamurthy and M. A. Elgar. 2000. Sperm competition and small size advantage for males of the golden orb-web spider Nephila edulis. Journal of Evolutionary Biology 13: 939-946

Scientists with suction

Author
by Blair
Publish date
1 May 2011
Comments
Comments (1)

I recently accompanied Richard Marchant to the Shoalhaven River where he studies the animals that platypus eat. Thanks to the suction sampling tool we used, I'll never look at a common household vacuum cleaner the same way again.

The underwater vacuum we used is a quite different to that used to clean carpets: suction, in this case, created by bubbles are injected near the base of a pipe. The bubbles rise to the top, sucking water upward as they go.

Diving for platypus prey Richard Marchant diving with the air-lift sampler, which works like an aquatic vacuum cleaner.
Image: Julian Finn
Source: Museum Victoria
 

When placed over a river bed or sea floor, small animals and sand are also sucked up with the water. A mesh bag covering the top of the pipe acts like a sieve; the sand passes out but the animals remain trapped.

This method of suction sampling typically nets catches of crustaceans, insects, and insect nymphs – important food chain species that can be identified and counted for research.

Richard emptying air-lift sampler Emptying the mesh bag of the air-lift sampler.
Source: Museum Victoria
 

The machine sounds weird too: a dull rumble through a dive hood, perhaps a cross between a V8 car engine and thunder.

The air-sucking principle of the vacuum means people refer to it as an 'air-lift'. It’s a nifty invention and a system used by many aquatic biologists at one time or another in their career.

Links:

MV News: Linking the food chain

Video: Studying the diet of platypus

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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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