The webs are built by the large females. At the tip of the abdomen there are three pairs of spinnerets, which secrete silk used to create the web. They usually face head down on the web. Orb Spiders are said to eat their webs each night along with many of the small insects stuck to it. They have been apparently been observed eating the web in just a couple of minutes! A new web is then spun in the morning.
So here is my ubiquitous Araneus diadematus with some more of the "lesser seen" angles - and you can see her... erm... lady bits quite clearly (epigyne)...
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