29 September, 2009

Zigzag Stabilimentum

When we first started gardening in Camps Bay, and everything was new, I was delighted to see a yellow spider web, with this zigzag. I was working in the Engineering and Science Library at the University of Cape Town. Synchronicity brought me that week’s Nature magazine with a cover article about cutting edge research.

Zigzag stabilimentum
The zigzag stitch is called a stabilimentum.
The spider’s mum taught him, after catching all that food, and collecting all that protein, and weaving that meticulous web – you need to be sensible and protect your investment. This spider has definitely been to one of Valeri’s textile art classes at http://mysmallcornishgarden.blogspot.com/2009/08/all-blogged-out.html
There is much controversy surrounding the function of these structures, and it is likely that different species use it for different purposes. Some people believe that they provide protection to the spider by either camouflaging it or making it appear larger. Another theory is that they make the spider visible and therefore animals such as birds are less likely to damage the spider’s web. Originally the decorations were thought to stabilize the web (hence the term stabilimentum), but this is dismissed nowadays. One more recent theory is that web decorations attract prey by reflecting ultraviolet light. Light in the ultraviolet part of the spectrum is known to be attractive to many species of insects. Many other theories have also been proposed such as thermoregulation, stress, regulation of excess silk, or simple aesthetics. At least one variant has been observed to vibrate the web, while positioned in the stabilimentum, when approached by a body the size of a human. One theory has been put forward that the purpose of the stabilimentum is to attract the male of the species to the web when the female is ready to reproduce.

Garden orb-weaver with
Blue Emperor dragonfly Lunch
When I photographed the zigzag the little spider shot off in horror. But his big brother has caught one of the Ungardener’s beloved dragonflies – looks like a Blue Emperor – sirloin steak instead of the usual hamburgers!

Common or garden white daisy
And now for my niece, who has had enough with the spiders already - your common or garden hybrid marguerite white daisy bush (came from a small piece hacked off a bush at my mother’s retirement village). Paradise for yellow or white crab/flower spiders, waiting on their dinner table with knife and fork raised in readiness, for unwary bees or flies who become Lunch (see post from 24th August).
You can also just see the yellow Clivia (more later) and our boma made of off cuts from discarded grapevines. Our neighbours tell us it makes wonderful coals for the braai (barbeque). As vegetarians and wildlife gardeners – this is our brush pile – snails hide and get eaten by tabakrolletjie snakes (see post from 4th September), lizards sun themselves and can escape.
And two frustrated cats say crossly – I know it is in there!


  1. I just love spiders -- great info on the zigzag. I guess I assumed it was to strengthen the web, but it sounds like there might be more to it. Excellent photo of the spider with her dragonfly catch, though poor dragonfly! Ah, but this is nature.

  2. Never seen anything like that before! One of the little wonders of this world.

  3. How fascinating! One of the things that I love about belonging to Blotanical are the other wonders in the garden around the world. Thank you for sharing.

  4. Such a stunning photo of that spider eating it's lunch -- poor dragonfly;-(

    Having never heard of, nor seen, a spider web with this amazing feature, I really learned a lot from you today! It's quite amazing!

  5. To Tatyana and Jan, if Meredith has seen it ... It is just the common garden orb weaver spider, which I think you have too? Have another look in your garden! I have seen zigzag photos on other Blotanist blogs.

  6. I'll take a closer look for this--maybe it is more common that I realized. I just haven't 'personally' seen one before, at least not that I've been aware of. BTW, I want to congratulate you on your Blot. award;-)

  7. I never heard of this. Thanks for enlightening us. And you did so much research on this. The life of nature is always very interesting.


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