Wallaman wildlife 3: Golden orb weavers

Golden orb weaver spider in web
Golden orb weaver in her web

I find myself with three quite different kinds of things to say about golden orb weavers, all inspired by seeing this impressive spider at Wallaman Falls a couple of weeks ago but otherwise unrelated. I will begin with the basic science.

Three species of golden orb weavers

Three species of large Australian spiders are commonly known as “Golden Orb Weavers”. They are all in the same genus, Nephila, and their common name refers to their webs, not their own appearance: they all weave orb webs out of golden silk.

This link will take you to full descriptions of all of them on Rob Whyte’s arachne.org  but, in brief, Nephila plumipes is the smallest and is found throughout eastern Australia, Nephila edulis is larger and heavier and is common throughout coastal and inland Australia, while Nephila pilipes is longer in the body and legs but slimmer and is a tropical and sub-tropical species. That means all three can be found in tropical Queensland, and in fact I have seen N. plumipes and N. pilipes within twenty metres of each other on Hervey’s Range just outside Townsville.

In all three species, the females are far larger than the males, to the extent that the females are the only golden orb weavers most of us ever see. All of them are quite timid and their (very rare) bites are not known to be dangerous.

So here we have a female Nephila pilipes in her web in a very public spot (yes, that building is the toilet block, and her web is between the verandah roof and the handrail, right beside the access ramp) at the Wallaman Falls camping ground. How do we see her?

Golden orb weaver in shadows
Scary?

Are we learning to love spiders?

In my couple of days at Wallaman I spoke to perhaps a dozen people about this spider and I was pleased to find that nearly all of them, after an initial startle reaction, were amazed, intrigued, respectful and even admiring towards her. They were happy to leave her in peace – although some did take care to stay a safe distance away – and happy to learn more about her. “No, she’s not aggressive and not poisonous,” went over well and, “Yes, those little ones are the males,” got a “Wow!” or two.

I would love to see all of us display such a positive attitude towards the traditionally scary or ugly creatures around us, and I think we are gradually making progress.

And by whose standards are spiders ugly, anyway? I think she’s beautiful.

Golden orb weaver
The ‘studio portrait’

Sexual dimorphism and gender politics

We hear a lot about sexual politics and the imbalance of power but I don’t know that we spend much time thinking about how body size influences the issue. Men and women are comparable in physical size and strength but men are, on average, a bit bigger and stronger so that when push comes to shove (as it does, all too often) men can usually dominate women physically – especially since men, bigger and stronger to begin with, developed their hunting and fighting skills while women focused on the softer arts of rearing children and gardens. That doesn’t mean it’s right, of course, but does go a fair way to explaining traditional power structures.

In our industrialised civilisation, of course, physical strength is less and less important, and we are seeing a gradual re-balancing of power which reflects that change.

What does this have to do with golden orb weavers? Well, ‘ladies’ like the one featured here have a body length of 50mm and their ‘men’ have a body length of 7mm. (If you can make out three tiny brown blurs on the edges of the web in the first photo, they are the males; if you can’t, here are two photos on arachne.org of N. edulis mating.) Scale that up to human size, and men would be kitten size, chihuahua size. What would that do to our gender politics, I wonder?

Can we even imagine a society in which the difference was so big? Would women in pre-industrial societies have kept men as pets? Could men ever achieve legal and moral equality, even in an industrialised society?

Golden Orb Weavers

spider in golden web
Golden Orb Weaver, Nephila plumipes, in its golden orb – the spider is named for its web, not its own appearance

Most people in Northern Australia know Golden Orb Weavers – very large spiders which weave metre-wide webs and are famous for catching birds in them – but not so many know that we have three species. They are closely related, of course, all being in the genus Nephila, and two of them, N. plumipes and N. edulis, are quite difficult to tell apart:

fat grey-brown spider
Golden Orb Weaver, Nephila plumipes
fat grey spider in web
Golden Orb-weaver, Nephila edulis, in web with prey debris

As adults, the females of both species are grey-brown with wavy markings on the underside of the abdomen. They are both large (as spiders go), although N. edulis at 40mm nose-tail can be twice the size of N. plumipes at 19mm. Both tend to leave a messy string of prey debris in their webs. The most positive way of separating them is that N. plumipes has a bright yellow sternum or chest.

The third species, Nephila pilipes (sometimes known as the Northern or Giant Golden Orb Weaver), is much more recognisable. It is slimmer in the body, its legs are longer in proportion, and from beneath it shows bright yellow knee joints and sternum.

grey spider with black legs
Golden Orb Weaver, Nephila pilipes, in web

This species is the only one I have found in my own garden. Every year or two we have one or two young ones blow in and make themselves at home until age or misadventure removes them. (I’m always delighted to see them, because they are so beautiful. Some other folk are not so enthusiastic, although they are completely harmless.)

Our latest arrivals, who prompted this post but have yet to appear in it, were first spotted on March 30. We lost sight of one three weeks later and the other last week but they were photographed several times before they vanished and will serve to illustrate the rather different colours of juveniles. This one (back/underside) is not much bigger than a St Andrew’s Cross spider and the abdomen is strikingly striped. Six weeks later the yellow highlights underneath are much brighter while the abdomen is almost the adult’s grey-brown on top and the top of the cephalothorax is the adult’s silver.

So much for the females. What of the males?

They are tiny. A particularly striking illustration of the difference is this photo on Arachne.org. (If you scroll up from it you will find one of the famous bird-eating photos.)

Since I have begun linking to other people’s material, here is a fossil Golden Orb Weaver (we now know they have been around for at least 165 million years) and here is Wikipedia’s page which has some pretty off-beat information as well as all the basic facts.

A prowl around my garden

I went for a prowl around my garden on Friday morning, camera in hand, to see what bugs were around. My intention was to take photos of everything, whether I already had photos of it or not, as a way of documenting (and reminding myself) what is active at this change-of-season time.

In the event I missed a few on purpose and a few because they were too quick for me but ended up with presentable shots of 25 species. I uploaded them all to Flickr and they can be viewed as a slideshow here (if it doesn’t work for you, click here to go straight to Flickr). For information about them, enter full-screen mode and click “show info”, or click on the photo to go to the Flickr page (new window).

What did I miss?

  • I saw many of the butterflies I mentioned in my previous post but didn’t bother chasing them;
  • a hover-fly, a brown paper wasp and a black and yellow mud-dauber wasp escaped before I could get a shot;
  • I could easily have taken photos of St Andrew’s Cross, Spiny and Silver orb-weaving spiders but I know I could do that any time;
  • I didn’t photograph all the species of small dark flies I saw, because there are too many and they are too similar; and
  • By restricting my collection to that one-hour prowl I missed the Eurema butterfly, Giant Grasshopper, Neon Cuckoo Bee and swarm of tiny bees I saw later in the day.

There’s a lot of life in a garden, if only you look!

Two spiny spiders

Black spiny spider with white pattern
Spiny spider 1

When I was a ten-year-old living on a farm in South Gippsland, Victoria, I would go down to the reedy swampy paddock at the foot of a steep hill and marvel at the enormous number of webs of a beautiful small spiky spider. On a dewy morning I could see them as an endless sparkling net stretched over the reed tips for yards at a time. (This was long before metres were invented, of course.)

I would encourage individual spiders onto my hand and watch them walk around, spinning their incredibly tough silk as they went, and I would examine their webs to see what they had caught. They were my favourite spiders – completely harmless, much prettier than the clever little leaf-curling spiders, and not big enough to be scary like the huntsmen.

black spiny spider with white pattern
Spiny spider 2

When I came to North Queensland I was pleased to find them up here as well – not so many of them, true, but just the same as the ones I remembered from my childhood. In my garden they make orb webs between the shrubs, often about face height (oops! sorry, spidey!) but sometimes a couple of metres higher. Their webs are often interlinked in loose colonies, although never in such masses as I remember from my childhood.

I never even considered doubting that they were the same species. I was wrong, though.

Spiny spider 1 is Austracantha minax, the Australian Jewel or Christmas Spider, and is found (according to the World Spider Catalogue) in “Australia, Tasmania and the Montebello Islands,” the latter being a small group off the WA coast near Karratha. It is the only species in its genus.

Spiny spider 2 is Gasteracantha sacerdotalis and it doesn’t appear to have a recognised common name. On the other hand, it has lots of other species in its genus, all of them spiny and many of them weirdly beautiful  – click here for examples from around the world. The World Spider Catalogue gives its range as “New Guinea, Queensland, New Caledonia”.

Spiny spider 1, Austracantha minax, is the one I knew and loved as a child in Victoria. It may also live in North Queensland but I have to say that I haven’t seen one here – all of mine here are Spiny spider 2, Gasteracantha sacerdotalis. Learning to tell them apart took me a while but here are the differences as I see them:

Austracantha minax (the southerner)

  • Back: the white pattern can be seen as a “V” with a few dots between the open ends.
  • Spines: rather long and unevenly spaced around the carapace – there are two very close together at each side.
  • Underside: bright yellow spots on a very dark background.
  • Legs: distinctly orange-brown

Gasteracantha sacerdotalis (the northerner)

  • Back: the white pattern can be seen as “M!M” with the outer legs of each “m” extended downwards. The outer part of the pattern varies somewhat but the centreline is constant enough to distinguish the two species.
  • Spines: rather short and more evenly spaced around the carapace.
  • Legs: usually black or very dark brown, often banded.
  • Underside: indistinct concentric bands of orange-brown.
Black spiny spider with white pattern
Austracantha minax
black spiny spider with white pattern
Gasteracantha sacerdotalis

These photos and descriptions all apply to the females. The males are much smaller (about 3-4 mm to the females’ 8 mm), less vividly coloured and rarely noticed. More pictures of females, and some of males, are here:

 

• Thanks to Volker Framenau, who alerted me to my mistake in the first place via comments on my photos on Flickr, and to Rob Whyte for use of his photo here and his ongoing encouragement of my arachnological pursuits.

Orb-weavers at night

As Rob Whyte says in his introduction to orb-weaving spiders, “When people imagine a spider most have in mind an orb weaver of some kind … with the spider waiting at the centre.” Most spiders in the family Araneidae, Orb-weavers, do in fact build this style of web but some subfamilies adopt other tactics; on the other hand, members of some other families, such as the large golden orb-weavers (Nephilidae) and the long-jawed orb-weavers (Tetragnathidae) do also build orb webs although they, “tend to be less sophisticated and often irregular instead of a neat spiral arrangement of the prey-capturing threads,” according to Wikipedia’s excellent overview of the family.

I have been looking them up since recently finding two rather large ones in my garden at night.

brown spider in web
Orb-weaver 1

Orb-weaver 1 is was the first I discovered. She was a bit casual about removing and rebuilding her web, often leaving some of it up all day (it didn’t bother us because it was high off the ground above some pot plants). It must have been a good location, because I saw four large butterflies in it (one of them, a Migrant, is here), as well as smaller insects, over the course of a week. I am reasonably sure she is an Australian Garden Orb-weaver, Eriophora transmarina.

Orb-weaver 2, side view
Orb-weaver 2, side view

Orb-weaver 2 was more disciplined about taking her web down at first light and rebuilding it each evening – a good thing, since it was at chest height across a pathway in our garden. (Guess how I discovered it. Yes, I walked into it in the dark. I was really sorry for wrecking such a beautiful web.) She may be a Knobbled Orbweaver, Eriophora pustulosa, although she is even knobblier than any of that species I have seen pictured (back view here).

Both of them could easily be long-term residents which escaped my notice for weeks by building their webs anew each night and taking them down each morning.

I should, in fact, get out at night more often – with a camera, I hasten to add. We all know that some animals and birds are nocturnal and that’s also true of smaller creatures. In fact, one spider enthusiast I met a while ago was quite surprised that I did all my spidering in the daytime, because he did all of his at night. We actually learned quite a bit from each other!

Just for completeness: Three families of smaller orb-weavers are very common in our garden – St Andrew’s Cross Spider (pics here but watch out, since one or two appear just because the text mentions the name), Silver Orb-weaver (pics here with its green and orange cousins) and the spiny Gasteracantha sometimes called the Christmas Spider. All of them leave their webs up 24/7.