SCV Outdoor Report: Arachnid Deception
By Wendy Langhans:
Deception is part & parcel of the natural world. Ancient legends and folk tales provide plenty of examples: the devious Coyote in Native American folklore, the Fox in Eurasian legends and Br’er Rabbit in African-American folk tales. Today I’d like to add one more to the list - orb-weaving spiders.
Orbs are webs shaped like a wheel with spokes. When the angle of vision and the light is just right, orb webs, like this one in Franklin Canyon, are readily visible.
However, it’s what we DON’T SEE that tells the tale. We know that certain spiders, such as our local Golden Orb Weaver (Argiope aurantia), spin two kinds of silk threads. One type reflects UV light and the other does not. Why does this matter? Well, we know that insects can see UV light and humans cannot. So UV reflective webs offer spiders a choice of at least three deceptive strategies that, until recently, we were unaware of.
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Deception #1. Hide in plain sight. If the spider has a cuticle (outer surface) that reflects UV light, it can hide in a section of the web that also reflects UV light.
Deception #2. The coast is clear. UV light is all around us. A web made completely out of UV reflecting strands will appear to an insect as open space.
Scientists are actively investigating the functions of UV reflective webs, but literature may offer us a hint of what’s to come. E. B. White, the co-author of “Elements of Style”, advised authors to “Be obscure clearly.” Was he thinking of spiders when he wrote this? Perhaps so. After all, he was also the author of “Charlotte’s Web”.
Upcoming Outdoor Events:
Saturday, November 20, 8:00-10:00 AM, Morning Bird Hike at Towsley Canyon. Towsley Canyon is a year-round home for many birds. For the permanent residents summer brings the heat and winter the rains. Amazing, birds find a way to tolerate the challenges and celebrate the rest. Beginners welcome, bring binoculars. For directions and trail maps, click here.
Saturday, November 27, 10:00-12:00 AM, Native Plants and Native Uses, at East/Rice Canyon. Not all shopping malls have walls. The local Native Americans were savvy shoppers, finding food, clothing and shelter right in their own backyard. For directions and trail maps, click here.
Trail Maintenance Schedule. Come join our volunteers as they help maintain our trails. Contact Steve at email@example.com for time and place.
Wednesday mornings, November 3, 10, 17, & 24.
Saturday mornings, November 13 & 27.
You can listen to stories like this every Friday morning at 7:10 a.m. on "The Hike Report", brought to you by your hometown radio station KHTS (AM1220) and by the Mountains Recreation and Conservation Authority.
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