The Orb Weaver or Garden Spider is a familiar sight in central Texas. They can grow quite large. The first one below was over 6 inches from leg tip to tip.
Their webs usually have a distinctive zig-zag pattern in the center. I searched to see if I had any photos of the pattern but couldn't find any. It's on my list now of things to photograph on one of my hikes.
If you search on the web, you'll find one. The pattern is called a stabilimentum and is thought to have several possible uses. It might be a lure to attract insects or it might be a marker to keep birds away and thus protect the web from damage. It might also be camouflage for the spider when it sits in the center of the web. Recent research suggests that the zig-zag pattern might actually decrease the visibility of the web to insects.
This is one of the things that fascinates me about nature and evolution. Although we may not know what purpose the pattern serves, the spider probably doesn't know either. No one needs to know actually, because the only thing that matters is that spiders that make this pattern in their webs are reproductively more successful. What a concept! It's also interesting that there is still uncertainty and debate about such a small, common feature. There is plenty of science left to do!
I photographed this one while working at the Onion Creek Water Quality Protection Lands. The wooden structure on the right is the top of a cedar (Ashe Juniper) fence post.
This one was near our garage. It wasn't as big as the one at Onion Creek but it looks very similar.
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