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DISPLAYING POSTS TAGGED: spider (2)

Hairy but not so scary

Author
by Chloe
Publish date
2 May 2012
Comments
Comments (0)

Chloe is a keeper with Live Exhibits at Melbourne Museum.

Who knew that within Melbourne Museum there are two rooms not considered to be in Australia?

Every year Australian Quarantine and Inspection Service (AQIS) officers confiscate thousands of objects being brought illegally into the country through the post, airports and seaports. These items include food, drugs, plants and even live animals.

King Baboon tarantula (<em>Citharischius crawshayi</em>) King Baboon tarantula (Citharischius crawshayi)
Image: Alan Henderson
Source: Museum Victoria
 

Such illegal items can pose a significant risk to Australian wildlife. Tarantulas are a long-lived spider which can produce thousands of eggs each year. If they were to become established in the wild exotic tarantulas would have the ability to decimate populations of small native animals.

In 1996 a population of Mexican Redrump tarantulas (Brachypelma vagans) was discovered in a citrus field in Florida, America. The population is believed to have stemmed from one gravid (carrying eggs) female who was released after she was no longer wanted as a pet. Over 100 individuals were found in a single survey of the 40 acre property. The Mexican Redrump tarantula is not native to Florida but has been imported for the pet trade since the 1970s. It is thought that this incidence of releasing an exotic pet has alone caused devastating effects on local fauna. With Australia's warm climate it would be easy to find ourselves in a similar situation to Florida if we didn't enforce strict quarantine measures.

Mexican Redrump tarantula (<em>Brachypelma vegans</em>) Mexican Redrump tarantula (Brachypelma vegans)
Image: Alan Henderson
Source: Museum Victoria
 

Tarantulas with their unique markings, behaviours, and basic husbandry are popular pets in Europe and America. Many species are illegally transported around the world with collectors willing to pay hundreds of dollars for specimens. In Australia there are numerous species of native tarantulas that can be kept legally as pets.

Venezuelan Sun Tiger tarantula (<em>Psalmopoeus irminia</em>) Venezuelan Sun Tiger tarantula (Psalmopoeus irminia)
Image: Alan Henderson
Source: Museum Victoria
 

Queensland whistling tarantula (<em>Selenocosmia crassipes</em>) Queensland whistling tarantula (Selenocosmia crassipes)
Image: Alan Henderson
Source: Museum Victoria
  

But what happens to the items AQIS confiscate? Many items are destroyed to protect Australia's precious ecosystem. However, some lucky spiders are spared. They get used by museums and zoos to act as educational aids.

Quarantine room enclosures off display at Melbourne Museum Quarantine room enclosures off display at Melbourne Museum
Image: Chloe Miller
Source: Museum Victoria
 

Melbourne Museum is home two quarantine rooms where we house 14 tarantulas that were confiscated by AQIS. These spiders are housed under strict conditions which meet AQIS standards. These standards include the treatment of objects leaving the rooms such as waste, water, uneaten food and other implements. These items must be double bagged, recorded and frozen at minus 20 degrees for six weeks. The quarantine room is not considered to be in Australia territory but a grey zone within Australia.

Bugs Alive! Quarantine room at Melbourne Museum Bugs Alive! Quarantine room at Melbourne Museum
Image: Chloe Miller
Source: Museum Victoria
 

One quarantine room at the museum is located within the Bugs Alive! gallery and allows visitors to see its inner workings through a glass viewing wall, while the other room is located behind the scenes.

Our display spiders are fed every fortnight on Saturdays. One of our 'behind the scenes' spiders is fed weekly on Fridays at 3pm live on the web.

Tarantula feeding live on the internet Tarantula feeding live on the internet
Image: Chloe Miller
Source: Museum Victoria
 

Currently on display via the webcam is a Brazilian Salmon Pink tarantula (Lasiodora parahybana). Brazilian Salmon Pinks are the third largest species of tarantula with a leg span reaching 25cm.

Brazilian Salmon Pink tarantula (<em>Lasiodora parahybana</em>) Brazilian Salmon Pink tarantula (Lasiodora parahybana)
Image: Alan Henderson
Source: Museum Victoria
 

Equipped with urticating (stinging) hairs to flick at predators, she only uses her fangs as a last resort. This girl is a keen feeder, often climbing up the keeper's forceps to get to its prey.

References:

Brazilian Salmon Pink fact sheet from WAZA

Brazilian Salmon Pink Birdeater from Australian Reptile Park

Mexican Redrump Tarantula fact sheet [PDF 179KB] from the University of Florida

1996 Florida Mexican redrump tarantula incident

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

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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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