Australian Orb Weavers Spiders
If you’ve walked through the Australian bush in spring or summer, chances are you’ve stumbled face-first through a spider web. One moment you’re enjoying a peaceful walk, and the next you’re frantically brushing silk from your face and worrying where the spider is... or maybe that’s just my bad luck. If not, lucky you, but if you have, most likely the web was the construction of an orb-weaver spider.
Orb-weaver spiders are named for the beautiful circular webs they construct. Australia is home to a remarkable diversity of orb-weavers, from the familiar garden orb-weavers that appear around our homes to the much larger golden orb-weavers found among trees and shrubs, or the distinctive two-spined spider with its strange, angular abdomen and contrasting colours.
Many orb-weavers rebuild their webs regularly, and some will take down the old web and consume the silk before constructing a new one. This allows them to recover some of the nutrients used to produce the silk rather than simply leaving their previous web behind. Interestingly, when creating a new web, the spider first creates a temporary, non-sticky spiral to use as scaffolding before replacing it with the sticky threads that will catch its prey. By early morning, dew may bead across those threads, revealing the magical web shape more clearly.
Garden orb-weavers are wonderfully variable in appearance, with different species showing an incredible range of colours and patterns. Their large abdomens and intricate markings make them particularly fun to photograph.
One of the things I’ve recently become interested in is what happens when these spiders are viewed under ultraviolet light. Some spiders and their silk can fluoresce under UV, producing colours and patterns that aren't visible under ordinary light. Fluorescence occurs when compounds in the spider or its silk absorb ultraviolet radiation and re-emit some of that energy as visible light. The exact function of fluorescence in spiders isn't fully understood, and researchers have proposed several possibilities, including roles in communication, camouflage or interactions with prey and predators. It’s another example of how much more there is to these spiders than we can see at first glance.
If you’re walking through the Australian bush this spring or summer, keep an eye out for those webs. And perhaps slow down before brushing one away. There might be a remarkable little engineer sitting at the centre. Once you start noticing orb-weavers, it’s hard not to stop and look a little closer.
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