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Sunday, September 23, 2012

The Redback Wrangler and the Film Star

Usually, red-backs are very common around Castlemaine. They're pretty common all over the east coast of Australia. Usually. But not this year. My arachnid guru, Alan Henderson, needs some redbacks for a film commission and put out a call because no-one could find them. Not one, not anywhere.

A member of the tangle-web Theridiidae family, the redbacks (Latrodectus hasselti) are closely related to the American black widow (Latrodectus mactans). I had all but given up on finding redbacks for Alan when I was tidying some pot plants for an elderly neighbour, Nina. There was a most unusual web in one of the pots. It was a funnelled web, shiny, like that of the theridiids, but with a distinctive funnel, which is not their usual style at all.  I took my new spider home and named her Arachnina after my neighbour. That night I shone the torch on the owner, and there was no doubt that she was a redback.



Enter the Redback Wrangler. 


Alan's daughter, Caitlin, came from near Melbourne to collect Arachnina. This is a rare image of a Reback Wrangler at work.


Arachnina was collected into a container, with her web and retreat, ready to make her trip to Queensland to become a film star. Meanwhile, one of the many scouts I had out looking for redbacks had turned up with an understudy, rather unceremoniously enclosed in a jam jar. The Redback Wrangler made our new spider more comfortable with twigs and leaves. The understudy soon started spinning herself into a safe retreat.


Soon after Caitlin had left, I received a phone call from another scout. A third redback had been located. Having received detailed instructions from Alan in addition to having watched Caitlin, I venture forth tomorrow - I get to be The Redback Wrangler.

Watch this space - Alan has promised a really good photo of Arachnina. A good photographer can make a film star look stunning. I let you know about her starring role when it is public knowledge. 

I know you are all intrigued to know what the partner of a Redback Wrangler eats. Admit it, you have always wondered. Here is the evidence of the shocking truth. Adam had a sandwich of thick vegemite, tomato and lots of pepper on wholemeal. I kid you not!

Wednesday, September 5, 2012

The saga of the golden orb weaver egg sac

I am waiting eagerly to see if the golden orb weavers emerge again this season. It's a real mystery what is going on. The summer of 2011 brought an influx of golden orb weavers such as the town had never seen before. Last year, there were none. As spring is springing, the obvious question is: will they return? And why weren't they here last year? One theory is given below. This year will tell if it's right! And the other mystery - how did the daddy long-legs know about the feast on offer?

First, a recap. When we moved to Castlemaine in Central Victoria, Australia, in April 2011, there was a glorious adult female golden orb weaver (Nephila edulis, family Nephilidae) at the front door to greet us. So she was named Welcome.

(click to enlarge)

With a body length of over 2 cm, she was huge. Not long after, Welcome produced a golden egg sac in the bushes nearby. It was already well into winter.


The first frost came and the morning sight was welcome dropping from her web. She recovered in the day's warmth, but the next day's frost killed her.


I watched that egg sac, checking it every day. Nothing happened throughout the whole winter. Up in Kalimna Park, where I was watching another half dozen Nephila, three made egg sacs, and all disappeared with the frosts. 

Now, Welcome had spun her egg sac in the wire on a garden arch which was in the wrong place for my garden design. To move it would have wrenched the egg sac from the plants, so I carefully cut the wire and placed the egg sac on the little front porch. Didn't think that through, did I? When the young hatched, they would use the breeze to disperse - and there's only one way the breeze could come into the enclosed front porch - from the front, carrying them nicely straight into the living room. This is what happened:


The egg sac had faded when I cut it lose in September 2011 and placed it on the porch. It was not until early January, in the summer heat, that I noticed a living bundle near it. Young, hundreds of them. I tried counting from the image below, but gave up.


Over the next few days, they spread and regrouped continuously, little white bodies appearing in the mass of brown as a mess of tiny shed skins appeared below. They were moulting, the slightly larger freshly moulted young showing off their beautifully marked white abdomens - only visible when I enlarged the photographs.


At the end of the week, they were well spread, never to regroup again.


A day with a light breeze and they dispersed on their tiny filaments of silk. It was then I realised that I was an idiot. They could only be blown into the house as a breeze doesn't come from the house out into the world. And they did - hundreds of them into the living room. All over the furniture. All over the ceiling. While they were still in groups, I collected them on brooms and other soft objects, leaving them outside to disperse again. But they spread, meaning it was a matter of collecting them one at a time. They were all over ornaments, such as this little one on the cage of a music box with toy songbirds.


But I was not fast enough. The greatest mystyery of all: within a few hours, five daddy long-legs spiders (Pholcus phalangioides, family Pholcidae) had gathered in the front corner of the lounge room where most of the young landed. I have no idea where they came from. We have a lot of daddy long-legs, but there were none in the living room that I had noticed. The daddy long-legs were having a feast. How did they know to come?


Spiders never cease to amaze and entertain me.

So now I wait. None of these young grew to adults during that summer. Despite the huge numbers in autumn 2011, there were none last autumn (March / April in Australia). Will any of them appear this season? 

Note on the confusing daddy long-legs critters:

An American reader has asked about the daddy long-legs in the photo above. Is it a spider or a non-spider harvestman?

Two different groups of animals are called daddy long-legs, the spider version and the harvestman version. Both have eight long spindly legs. Both are arachnids. I gather Americans are more likely to call the spider version 'cellar spiders'. 

The differences: spiders have two body segments with the legs coming from the front bit, the cephalothorax. Harvestmen only have one body segment.  The spider version make webs while the harvestmen don't. Spiders are much more likely to be inside the house than harvestmen. I photographed huge harvestmen in Texas.



If you look at the image on the blog, you'll see the daddy long-legs has two body segments while the harvestman above has only one. Because of the confusion, arachnologists usually refer to the spiders as pholcids and don't use the 'daddy long-legs' common name.


References:

A great reference for Australian spiders is being developed at Arachne.org.au:

http://arachne.org.au/

This site is a working draft for "A field Guide to the Spiders of Australia" by Robert Whyte and Dr Greg Anderson for CSIRO Publishing due to be published in 2014-15.

I'll be using it as my prime site for classification from now on.

Postscript: Greg Anderson has sent me a fascinating paper on Nephila. It seems the questions I am asking about N. edulis are not answered - yet! Plenty of research to do which can be done by ordinary people out there watching them. 

"Given the large number of studies that have focused on the behaviour and evolutionary biology of Nephila spp., it is some- what surprising that little work has been undertaken on their population biology. In the Sydney region, adult female N. plumipes are univoltine, appearing in late December to February (depending on the year), and reproduce from late summer to autumn (February–May) (Austin and Anderson 1978; Elgar et al. 2003a). From June to September (winter–early spring) the population comprises a range of immature size classes, and a declining number of adult females that have all disappeared by August–September. This pattern becomes more complex in the northern, tropical part of the distribution of N. plumipes, where the breeding season is more prolonged, and populations may be bivoltine (A. Austin, personal observation).

Far less is known about the population biology of N. edulis, which occurs throughout the arid interior of the continent (Fig. 87). In arid regions this species appears to have more tran- sient populations, where dense aggregations of adult females will occur at a particular site in one autumn and then disappear, often for many years (A. Austin, personal observation)."

Reference: Harvey, Mark S., Austin, Andrew D., & Adams, Mark. The systematics and biology of the spider genus Nephila (Araneae: Nephilidae) in the Australasian region. 
Invertebrate Systematics, 2007, 21, 407–451






Wednesday, March 7, 2012

Fourlegs - a huntsman with only four legs

I have a new favourite, who I worry about every night. He is a juvenile huntsman, Holconia immanis, who has been in the wars. He has only four legs, and they are all on one side. Every leg has been dropped at the at the coxa-trochanter joint, near the body. He also seems to have lost the palp on his right side as well. I have not read of spiders dropping palps, but they are more correctly called pedipalps and are small legs, so that seems reasonable. (Click on images for a larger picture, if you really want to.)

Fourlegs, the night I first met him.

Dropping the legs has been done voluntarily by the spider. The ability for a spider to decide to drop the leg is called autotomy, which is under the spider's control. Apparently they don't do it under anaesthesia. Muscles close over the joint, the haemolymph (blood) pressure then presses on the joint membrane and seals the wound.

To drop four legs, poor Fourlegs must have been in a tight spot - either something had caught his legs, or he had trouble extracting them when moulting - so the legs are still in the shed skin. If bitten by a wasp or bee, the spider can drop the leg before the venom gets to its body. I don't know Fourlegs' story, but given it was four at once on one side, I am tending to believe it was a moulting mishap.

If Fourlegs moults again, then the legs will regrow, although they will probably be smaller and weaker. But at least he'll have them. If he's an adult, then this is it for life.

I've seen lots of spiders with seven legs, a few with six and even occasionally five. But never four. And all on the same side looks horrible.

The good news!!! Fourlegs was feeding last night. You can see the mashed black thing he is holding to his mouth, which is on the underside of his front section, his cephalothorax. He is using his left palp over on the right side and often seems to balance by bringing his left foreleg right across.

Fourlegs feeding, on the second night.

He also seems to have spun some silk around and is using it to help maintain balance. He looked very weird with his legs in a strange position, and hanging suspended, but I wonder if it was the only way he could hold his prey. I was sure he was dying, but he was there again tonight, and all is well.

Fourlegs balancing to feed.

He has been out for three nights now - so has survived this way for at least three days. Not far from the same spot. I will keep you updated if I see him again.

Just in case you want a lovely photo to finish on, I did manage to photograph a spider of the same size and species a few nights earlier, about ten metres from Fourlegs' current location. I have decided that it was him - because I want to. Don't look too closely and spoil my delusion. The rose thorn gives you an idea of his size.


Please don't make any gory or sick jokes about my spider. I am extraordinarily fond of Fourlegs and desperately want him to survive, moult and have to be renamed Eightlegs.

Thursday, March 1, 2012

Huntsmen - the gentle giants

When I was interviewing about arachnophobia for the book, it was the huntsmen which were mentioned most, causing far more fear than spiders which could actually do harm, such as the red-back. It's all about size, hairy legs and their unique ability to suddenly be on a wall where there was no spider just a second ago. Then - even worse - to be gone again. Where? (Click on spiders for larger image).

Badge huntsman, Neosparassus diana

There have been three different species of huntsmen (family Sparassidae) around the house so far this season. This adorable badge huntsman, Neosparassus diana, nearly ended up in the rubbish bin. Fortunately I noticed her just as I was going to throw the plastic bag in the bin. 

Badge huntsmen are smaller (about 16 mm body length when adult) compared to up to 22 mm or so for the larger species. They also tend to crunch up like this, and look most un-huntsmanlike. They are claled badge huntsmen because they have a 'badge' on the underside of the abdomen. This little one had been hassled enough, so I didn't put her on glass to photograph. She eventually got enough confidence to unscrunch and run under the table leg on the verandah, as in the first image. But fear not, I can show you a badge. Here's one I prepared earlier... (That's not his web. He's just near a black house spider web on the window).


Spiders on the window are not unusual - they are taking full advantage of our light bringing in dinner. This is the social huntsman, Delena cancerides. In the wild, they will often live in groups under the bark. This is unusual for spiders who tend to be solitary creatures unless they are after sex. Social huntsmen are large and common, up to 22 mm body length. Here is what we see from the loungeroom.



And here he is from outside.


But my favourite huntsman has been a young guy who lived in the house for a few weeks. He was known as Little Friend because he seemed small for a huntsman. Maybe he was a juvenile, because he was hanging around last May. I think he is a young spotted huntsman, Holoconia immanis, but I'm not certain. He would appear from flat openings we hadn't even realised were there, such as this door edge. [Update: May 2013- I finally identified him! He's a Victorian Huntsman, Isopedella victorialis. Thanks arachne.org.au]


Mostly he stayed hidden, so we'd go days without seeing him. Then he'd appear. The photo below is on the kitchen ceiling when he decided he didn't want to be photographed - he's rearing up a bit and showing his fangs. I'm underneath him. They have no trouble hanging on when upside down. Incredible creatures!


Some visitors were a bit concerned about his strolling up and down the corridor continuously one day, so I conceded and put him outside.


He strolled across the window ...

... and was soon back inside. I was delighted. I just didn't tell anyone, and he stayed unobserved until the visitors left. He stayed around for a few more weeks, then was gone.

I've been very busy with finishing my doctoral thesis and my new job - a few days a week with the wonderful students at Castlemaine Secondary College. But I have a lot of photos and they will all end up here.

Update on the regulars:

They all disappeared, and I don't think any of the garden orb weavers (Eriophora pustulosa) made it to breeding. How sad is that?

But my golden orb weaver (Nephila edulis) did brilliantly - Welcome's egg sac hatched!!!! I ended up with a houseful of tiny orb weavers. That's a story to tell in the next blog!