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Monday, December 27, 2010

garden orb weavers - an amazing coincidence - or is it?

At the end of my story, I will ask the question again. Is this a coincidence or the sign of something significant?

I was delighted to be pointed at garden orb weaver photos on Facebook. Andrew Peter had discovered a large orb weaver (Eriophora biapicata) taking advantage of the light on his back porch.


She was the most typical colouring for Eriophora biapicata. He named her Regal jr., after my Regal, who has featured before on this blog. In the middle photo, Regal jr has just finished a meal. The mangled remains are to the left of her mouth.


Unfortunately, Regal is no more. Her web was ruined two nights ago. The main strand was in place, but the web had been ripped - just the way it is when a night bird rips a spider from her web. I have seen it. I had a torch on one of these orb weavers watching it one night when a frogmouth (an insectivorous night bird) flew straight into the web, snatching the spider I had so generously lit up for it. I felt terrible! But I digress. Back to my story.

Andrew had two other orb weavers in his sights. And two of his photos caused me a shock:


These are clearly Eriophora, but there are strange bumps on the end of the abdomen. It cause me a shock because I had just photographed this little spider on my back porch, having never seen those humps before. Was I seeing a deformed spider? She was also a strange colour. Resting in the grouting of the brickwork, I named her Groutesque.


A bit of research soon identified these spiders as Eriophora pustulosa, which is not an uncommon spider, but I have never seen one before. 

So is this a coincidence? Or are these spiders changing their range and becoming more common in the Melbourne area? I'd love to hear from anyone else who has noticed them, or knows anything about them. Meanwhile, Andrew and I will keep watching.

I am delighted to report that Andrew is now an addicted spider watcher, even enjoying messing aorund with his photos in Photoshop for Christmas. Isn't this gorgeous?



Thank you so much to those who have been writing to me and saying how much they are enjoying the blog. I'd love to compare notes with other spider fans. So little is known about spider behaviour in the wild. Our observations may well highlight new behaviours.

Thank you, Andrew, for allowing me to use your photos. I hope you will contribute to The Spiderblogger again soon. Please let me know how Regal Jr is getting on.

Must go now - I want to play with spider images in Photoshop!

Sunday, December 19, 2010

Regal and Ivy - garden orb weaver joys

I have been watching two of the garden orb weavers (Eriophora biapicata) in particular. Regal and Ivy - both named for the type of pelargonium they have chosen to live in. Regal was introduced in the first post (Dec 4) and featured on Dec 7. Ivy is smaller and a bit lighter in colouring. The trouble has been that I just haven't been able to find Ivy's resting place, despite many attempts to do so. I could see her web, and watch her each night, but she was just too well hidden in the leaves during the day.

Tonight I went out at dusk and watched and waited. One of the dead leaves stood up. I had found my spider:

By clicking on the image, you will find her easy to see.

She has a vertical main thread on which she posed beautifully to have her photograph taken. You can see four of her tiny, fairly ineffective, eyes on the front of her head.


Meanwhile, Regal had rested very comfortably (or so it looked) all day. She is getting a little darker as her leaf dries up:


Tonight, Regal emerged and went straight to the remains of a shrouded fly which had been in the remains of her web all day. She decided to finish off her leftovers before taking down the web to make a new one. Leftovers first:


And then it was time to take down the old web and start again. But a web is protein and a spider needs a lot of protein, so Regal didn't just drop it. The debris was dropped to the ground, and the web pulled in systematically and eaten. Here she is, pulling it in and eating the silk.


Every night, without fail, my orb weavers are doing something interesting. Free entertainment. Love them!



Gutsy - the black house - and young!

Gutsy, introduced only yesterday, is a black house spider (Badumna insignis). She looked thin, so I had assumed that she was just not fully grown. How little did I know! Tonight she emerged, and a hoard of miniatures versions emerged with her. Click on the images to have them enlarged.


I was duly excited, but Gutsy wasn't quite as content as she usually is with my presence, camera and flash. She turned and returned into the safety of her retreat. And most of the young turned and followed her:


How cute is that?!?

An hour later, Gutsy was out again, but with no young. How does a spider tell her spiderlings to stay indoors?

Friday, December 17, 2010

The Mystery of Black House Sex

OK, this post won't win any awards for photography, but I have been puzzling over the antics going on in the webs of mature female black house spiders (Badumna insignis), introduced in the December 10 post. There are almost no behavioural studies done on this spider, despite how common they are. The mystery is all about sex and size. Spider sex and spider size.

First - a photo of exactly what these spiders look like in their usual location. This is Gutsy, so named because she stays way out on her web no matter how close I get. Most black house are pretty shy and retreat as soon as they detect my presence.  Gutsy has her web funnelled into a crevice in the brick work on the edge of the window frame on the right of the photo. Hence there is no way of seeing into her retreat.


Some black house spiders make their webs on the panes of glass on the back door. I can see into their retreats - not perfectly - they cover the glass with silk. This is a pair in Pane 12. Guy-in-12 and Girl-in-12 have been together for about 2 weeks now. They are often touching, so definitely a pair. I photographed them with a ruler, so you can get an idea of their relative size. Guy-in-12 is the smaller of the couple.


But there is often a Little Guy as well. I have noted these before, photographed close up enough to see the engorged palps which indicate a male. They seem to arrive about the time that the females become mature. I have even watched one of the Little Guys mate - or so it seemed - with a recently moulted female. Males of quite a few spider species will hang around a females web and mate with her just after her final moult. She is finally able to mate but still fairly defenseless with her body soft from the moult. In Pane 12 today, there were all three - Little Guy is out to the left:


So who are these Little Guys? They are in most of the webs of my mature females. I had mentioned this on another site, and received a fascinating comment on the December 10 post. wolfatron wrote:

"I have recently surprised myself and become extremely attached to what I discover from your posts, is a black house spider. She lives in the window of our shower and so every morning while I'm showering I catch up with her and observe her incredible life. I read in some posts of yours about this spider, that you had observed some very small individual spiders sharing the web. Did you ever find out what these were? I have been assuming that they were the male. I have a few other females living in various parts of the house and they all seem to have a small spider in with them at the moment."




I have spoken to arachnologists who were unable to tell me what was going on. They are still pretty busy just classifying our spiders - most have yet to be done. The only way they could investigate was if I killed a little guy to go under their microscope. I couldn't do that! I am irrationally obsessed by my spiders. So what is going on?

I have two theories:

1. Maybe these little guys are kleptoparasites, much like the small dewdrop spiders Argyrodes species (Family Theridiidae), who hang around on the webs of larger spiders, such as the golden orb weaver (Nephila sp.) webs, and pinch their host's prey. My Little Guys are the wrong shape for a theridiid, but maybe they are another species of kleptoparasite.

2. Are these the males of the smaller species, the grey house spiders (Badumna longinqua)? Maybe the two species, being the same genus, can't tell the opposite gender of the other species from their own. That is not unknown in spiders, but only the same species has genitalia which matches perfectly, and hence they can mate successfully. 

I don't think they are kleptoparasites because they seem to only arrive when the females reach maturity. But they are also smaller than I would expect for the males of B. longinqua. So it is a mystery.

I am really hoping that wolfatron will watch his Badumna and we can exchange notes. I also hope to hear from any other Australians who have these fascinating creatures and can watch them as well. Or maybe you have a different theory. I'd love to hear from you in comments or by email.

Oh, and an update on Guy-in-one and Girl-in-one. She killed him. Having told you how they can happily cohabit, I couldn't see him through the glass yesterday. I went straight outside and looked up. There was his body, strung up in the web - dead. I like to think that he died of natural causes, but I have to face the truth. She just didn't want him around any more. Now to watch Guy-in-12 and hope that he leaves of his own accord.

Tuesday, December 14, 2010

Enemy Number 1 steals a web

The Number 1 Enemy of my spiders doesn't only eat them - birds know that silk is the perfect material for binding and lining a nest. It is flexible, strong, will bind the other nest material and will not rot - in fact water will run off. So it is no surprise that the many visitors to the back verandah steal silk.

This morning, an Eastern Spinebill, my favourite bird, landed on the verandah rail. I have planted salvias all around the garden just to draw this bird into the house. They hover over the flowers much like hummingbirds in other countries. But they are bigger, about the body size of a sparrow. Then I noticed that she was looking back and forth surveying the webs along the eaves.


She made her choice, took off ...


... and removed an entire web, belonging to one of the black house spiders (Badumna insignis).


Tonight I went out to see how the deprived arachnid was coping. There was fresh silk. She was starting again.

Sunday, December 12, 2010

Introducing the daddy long-legs spiders

I adore these gentle leggy spiders. The name 'daddy long-legs' is also given to the harvestmen, which are not true spiders, having a single body section. But this blog is about the spiders version - Pholcus phalangioides, Family Pholcidae. Before I introduce the blog star, I must add my favourite photograph, taken of a spider who lived under the table in the lounge room for a long time.


Isn't she incredibly elegant?

Please meet Mother-cups, the daddy long-legs who is definitely a mother - holding her egg sac in her jaws, in one of the kitchen cupboards above the coffee cups. She just sits there patiently waiting for them to hatch. I adore watching the young emerge, the greatest confusion of legs you could ever see.


I have seen a female with an egg sac take prey. When a fly was caught in her web, she attached her egg sac to the web, left it there, had dinner and then returned to take her egg sac in her jaws again.

It is a myth that these gorgeous creatures have the most dangerous venom - they don't. They can pierce the skin, but it is very hard to get them to bite. They are just too docile. They feed often on other spiders. I have had a few hundred breed in the kitchen and lounge area over the last year or so, but there are only a dozen in residence. I have a feeling they ate each other.

I adore watching the males and females as they share a web, which they often do for weeks. They will twang the web at each other constantly communicating, and eventually the male will make his approach. At times he will make a sudden retreat, obviously she is still not ready! Their vast webs are a means of detecting the world and communicating with each other. I will blog them often - they are my constant companions in the kitchen. But the moment I am really waiting for is to see Mother-cups' young hatch.

Everyone in the world can have the pleasure of watching these beautiful spiders. Just leave their webs alone and use a strong torch to get a good look at them. Their egg sacs are clearly visible, and with a strong torch, each egg is visible to the naked eye. There is no better spider to watch and enjoy.

Red-backs and other theridiids

I have been happily watching the small spider grow and weave - through the clear plastic of the stool I use of the back porch as a foot stool and occasional table. It was clearly a theridiid (Family Theridiidae), and we have plenty of the commonest theriidid in the world, the American common house spider (Achaearanea sp.) on the verandah. I'll introduce them below.

This morning I noticed that she was getting to be a very very large Achaearanea.  The deadly red-back spider (Latrodectus hasselti) is the same shape. Surely I couldn't have been that stupid? I was.

I turned over the stool and the distinctive red stripe on the pure black back was clear to see.


Around her were the bailed up bodies of spiders, a favourite prey of red-backs. Beneath her was a recently shed skin. Adore every spider as I do, I have to be realistic. We have children visit and play on that verandah regularly. She couldn't stay for me to watch. But I hadn't been at any real risk with her there under the foot stool.

Red-backs haven't killed anyone for about 50 years - not since the anti-venom became available. Neither have their very close relations, the other deadly widow spiders, including the American Black Widow (Latrodectus mactans) and other highly venomous members of the Latrodectus genus. But the bite is apparently horrific, although the spiders are notoriously shy. I knew that she wouldn't rush at me or attack - that only happens in movies. It is an unfortunate coincidence of nature that her venom is so dangerous to us, as well as her intended prey.

The harmless little theridiids, which are probably the most common spiders around houses worldwide, are the Achaearanea. They tend to be pale and well hidden in their messy tangle webs. They are great to watch - they hunt and catch prey way larger than you would think possible, the egg sacs sit in the web and then hatch with the young staying with the protective mother for a week or two. They mate in the open, and put on quite a show. I'll be blogging all this during the summer. But here is an Achaearanea, just for introductions.




They have only six eyes, as can be seen on the front. She is only about a centimetre in body length, but with extraordinarily long legs. 

Most of mine never make it to mating - birds regularly grab onto the frame of the glass door panes, and systematically pick off every spider as they do the rounds. Below is a white-throated treecreeper, as I saw her through the door panes, carefully making sure that she didn't miss a single arachnid morsel.  At the moment, I have no spiders on the front door, thanks to the attention to detail paid by a pair of white-browed scrub wrens nesting out there, who I see most days checking out the window panes for new residents. These guys are the Number One enemy! 




Friday, December 10, 2010

Introducing the Black house spiders

The black house spiders are my favourites. OK, these photos aren't as pretty as the orb weavers, but I really love these guys. I can watch them all the time, because they build their funneled webs all over the house. Webs are not cleaned off, and so they build up as new spiders take over old webs. The back verandah is a lacework of webs with about 70 spiders out there at any one time, 30 or so on the door panes. There are two species, the larger black house and smaller grey house (Badumna insignis and Badumna longinqua, Family Desidae).

In their funneled webs, Badumna longinqua (l), body length about 14 mm, and Badumna insignis (r), with a body length of about 18 mm. The males are about half the size of the females.

I will blog these spiders a lot, because they are my constant companions. Mostly it will be the larger of the two, B. insiginis.

In this post I will just introduce the three individuals who I have chosen to blog. They live on the back door, which consists of 20 panes. The numbers in the names refer to their door panes, numbered, not very originally, from 1 to 20. 99% of spiderlings do not make it to maturity. For 4 years I have been leaving the webs on the door panes, in the hope that one day I will see a female making her egg sac, and then see the young hatch. But the birds usually take the spiders when they get to a good size. Today I finally witnessed an egg sac being made!

Mother-13 was clearly gravid - ready to lay. Her abdomen was quite swollen. This was what I could see through the glass pane yesterday. This is into her retreat, so she has lined it with silk. But at least I can see her.

Mother-13 ready to lay.

Then, this morning I saw it. Mother-13 was spinning her egg sac, which she had attached to the glass. Here she has just finished. You can see how much of her abdomen full of silk has now become egg sac and eggs.

Girl-in-one and Guy-in-one are a male and female in pane one, who have been cohabiting for two weeks now. Most male spiders do not become dinner for their mates - that's just a few species. I am hoping for another egg sac at some time soon. This is how they look to me from inside the kitchen.

The smaller male, Guy-in-one, above, and the female, Girl-in-one, below, are cohabiting. The female would not tolerate another living creature in her web other than a male. She'd eat it.

Upsider is a much more typical black house spider, in that she has her retreat worked into a crevice. In her case, it is into the brickwork next to the door. She always rests upside down. An individual will tend to always rest in a particular orientation, even though the entrance appears to be pretty regular to me. 

If you look closely at the full size (click on the image) then you will see that Upsider's fangs act like pincers - pointing toward each other. That's the way they are in most spiders, often referred to as 'modern' spiders. The 'primitive' spiders - trapdoors, Australian funnelweb spiders and mouse spiders - have their fangs pointing downward. They raise their front half to strike down on prey. I will blog our Victorian trapdoors in another post. Upsider has 8 eyes, in rows along the top of her head (well, bottom of her head, given that she is upside down). The eyes are very small, and mostly detect light. Upsider detects the world through her sense of touch - through air movement over her hairs, and through the web.

You have now met them. They live pretty active lives, as future posts will show.

Update:

Regal fed extremely well today. I couldn't identify the shrouded creature, but I would guess it was a large flying beetle.


An hour outside tonight, and I counted 34 orb webs. Most will not make it to full size, but some will. It's going to be a wonderful summer!




Tuesday, December 7, 2010

Garden orb weaver - Regal

Regal (introduced on December 4) wove a perfect web. She'd been constrained by the dense shrubbery, so I carefully pruned it away. Last night she wove a full sized orb web. The full web would have been well over a metre across - they are capable of much larger. The orb was about 80 cm in diameter. She is only about 2 cm in body length. Pretty good achievement?

Clicking on the images will show you Regal in all her glory.


The beauty of these spiders is the way you can see all their body parts. Here's Regal from the other side.


At the tip of her rear end are the spinnerets, where she pulls up to 6 different kinds of silk to make her one web. Humans haven't managed to make any material as strong and light, and certainly not at room temperature. Incredible stuff - very flexible, impervious to water, rot and fungi - and incredibly strong for its weight. Her main guy thread across the top, which she reinforces every night, is really strong to touch. There is a good reason the birds keep pinching webs for their nests.

Directly below Regal's spinnerets, just above her waist (pedicel), is her epigynum - the reproductive tract. On either side are her lungs. Despite the way many people draw them - you can see clearly that all her legs come from the cephalothorax - none from her abdomen. The blobby bit at the front is something she is eating - just finishing, judging by what a mess it is. The mini-legs / pedipalps / palps are a bit like hands, and used for all sorts of manipulations.

Regal detects the world by feel. Her eyesight is pretty pathetic. But those hairs, especially the stiff ones you can see, are incredibly sensitive. So she knows what's going on through touch. Her web is, in effect, an extension of her sense of touch. Spiders are hairy, because otherwise they wouldn't know what was going on in their world.

And here she is at rest today. You can see why she's the colour she is. Those dreaded birds would be hard pressed to see her. She's on the right of the dead leaf mass.



I have a feeling Regal is going to be the most photographed spider in the world.

Update:

Rocky (one of the wolf spiders introduced on December 4) has moved the bit of bark in the photo, back over her burrow. She is not the first wolf spider I have had who loved a particular bit of bark.  Theresa, whose story I told in the book, had a roll of bark which was always near the edge of her burrow. One day her burrow was dug up by the large birds who dig up lots of my wolf and trapdoor spiders - the white winged choughs. They didn't get her. That night, she emerged, still with some young on her back, covered in dirt, and started to repair her burrow. The first thing she did was go and get her roll of bark and bring it back to the burrow entrance. She then descended for the night. It took her two weeks to fully repair her burrow. Pity she wasn't so lucky at the next chough attack. Rocky's burrow is very exposed, so I hope she escapes the notice of the choughs. At the moment, with her bit of bark over the burrow, I doubt any bird would detect her. The burrows are usually wide open when there is just the one spider there. When they have young, they keep covering and uncovering it. I hope to see Rocky's young soon. Like all wolf spiders, she'll carry them on her back for a week or two.

That's the photo I want to put here.

Saturday, December 4, 2010

Introducing the garden orb weavers and wolf spiders

So much is happening in the surrounds of the house that I will try and record just some of it here. There are too many spiders to introduce them all, but that won't stop me trying. Clicking on the images will enlarge them.

The most dramatic are the garden orb weavers (Eriophora biapicata, family Araneidae). I have two just outside the back door who are making sizable webs already. This is Regal, named such because she is located among the regal pelargonioums.  She isn't making proper orb webs, constrained by the many branches of the shrub around her. I pruned a bit yesterday to try and help. Any location with a spider becomes sacred ground - pruning, digging, walking - they're all limited to minimize the impact on the resident arachnid.


Garden orb weavers will change colours according to their surroundings, so they vary enormously, which makes them visually stunning companions. Regal rests on dried leaves in her bush and is almost impossible to see there without searching for the leg which will be monitoring the web - just keeping in touch (literally) with her hunting grounds.

I have at least three species of wolf spider (family Lycosidae), some are free range hunters, but the large burrowers are the ones I get to know as individuals - Lycosa godeffroyi. There are two, one in each of the vegetable gardens, who have their domains fenced off, and we garden around them.

Cucumber (named after the crop her bed held last year) is as cool as her name. She will sit out sunning herself, as wolf spiders love to do, even as we garden around her. She is extraordinarily confident. Only young, this is her first season. She moulted in the last few days, and is now near to full size.

Cucumber is sunning herself outside her burrow, cleaning her chelicerae (the bits which hold the fangs)
She's using her front pair of legs and her pedipalps (aka palps) to clean off the grime left after a feed. I think the white blob is just a small pebble on her back. I hope it isn't a parasitic maggot. I guess I'll find out when I see her next. You can see her two large and four small eyes (in a line underneath her large ones) on the front of her head. Two more on top, totalling 8. You can also see bits of silk everywhere as she has woven her chosen pieces of straw, and even the living plant, into her burrow architecture.

Cucumber eventually got sick of me and headed back into her burrow.
You can see the pair of posterior eyes on the top of her head, giving her a total of 8.

Rocky has a circle of rocks surrounding her massive burrow in the corn patch. She is in her second year, so large - about 2.5 cm in body length alone. With her long legs spread, she'd be more than double that. Rocky is extremely shy. I have to start sneaking from 5 metres away for a chance of seeing any more than a fleeting glimpse of wolf spider disappearing down her burrow. She holds the egg sac in her hind legs, face down into her burrow, so her eggs can get warmth of the sun.

Rocky's blueish egg sac, held by her hind legs - one visible on the right.
You can also just see the spinnerets at the top also holding the egg sac.

Rocky's egg sac in her rock circle. She pulled the small piece of bark over the burrow to hide it when she was making her egg sac.
I haven't yet introduced you to my favourites - the black house spiders. That will have to be another blog.