Spider Web Colors
Lasers? Northern Lights? Woven belts? No, this is a spider web. Lately I’ve been fascinated with one of the eight-legged arachnids— spiders. I want to share some information about our local spiders, their importance to our ecosystems, and their beautiful webs.
1. Clockwise: Cross Orbweaver (Araneus diadematus); Oblong Running Spider (Tibellus oblongus); Thin-legged Wolf Spider (Genus Pardosa)
How many spider species do we have in Washington? Exterminator websites claim there are between 24 and 34 confirmed species. I wrote to ask Dr. Rod Crawford, the professional arachnologist and spider curator for 50 years at UW’s Burke Museum, who has helped me identify several species on iNaturalist. Rod said we actually have “968 and counting.” As for the Olympic Peninsula, he says, “we can assume it would be several hundred species.” Rod worked for six months on the Elwha River Biological Survey in 2008, a project to establish a biological baseline before removal of the dams, which “got us about 150 spider species, just from that one river.”
2. Goldenrod Crab Spider (Misumena vatia) on Bistort
Rod doesn’t have a favorite spider species, but I do. Here’s the first Goldenrod Crab Spider (Misumena vatia) I ever found. While I was hiking at Hurricane Hill, this bright yellow and red spider stood on blossoming Bistort holding up its long front legs, just like a crab’s pinchers. This spider’s walk does look a bit like a crab, too. Because I found this one so high in the Olympic Mountains, I assumed crab spiders were rare, like the endemic wildflowers and marmots. A few days later, sitting outside the Port Townsend Co-op, I noticed another.
3. Goldenrod Crab Spider (Misumena vatia)
Then I started to find Goldenrod Crab Spiders in my garden, often sitting on my dahlias waiting for insects. They are ambush predators! They also like to wait for insects in goldenrod, for which they’re named. They can be yellow or white, like this one showing its eight eyes, its two furry-looking front mouthparts called chelicera, and its two sensory feelers, or pedipalps, touching the leaf.
4. Zebra Jumper (Salticus scenicus)
Another of my favorite spiders is the size of a grain of rice: the Zebra Jumper (Salticus scenicus). I noticed one climbing on a window right beside me inside my house. My macro lens revealed its rather adorable black and white, striped body. A spider’s anatomy includes four pairs of legs and up to eight eyes as part of its cephalothorax, followed by its other major body part, the abdomen, which at the end includes spinnerets to make silk.
5. Jumping Spider (Habronattus americanus)
One spring day I was at Ft. Worden for the Coastal Cleanup. I was sitting on driftwood, picking up small pieces of colorful plastic and styrofoam on the beach. I noticed a bright piece… moving! My phone was all I had to document this spider, and it doesn’t do justice to the cutest spider face of all. (Please do a web search to see better images.) Jumping spiders don’t spin a web because they don’t need to; they have good vision and they can jump around to look for their prey— small insects and other spiders. Hoping to get a better view of this extraordinary spider, I asked Rod if the Burke Museum has a spider collection. And they do have the Pacific Northwest’s most diverse and extensive collection. But, unfortunately, all the spiders are carefully stored away in vials, so there’s no public exhibit. Rod shared this website with photos of his vials, other “tools of the trade,” a map of his WA collection sites, and more: https://crawford.tardigrade.net/journal/
6. Thin-legged Wolf Spider (Genus Pardosa) with Egg Sac
There are 240 species of Thin-legged Wolf Spiders in North America, and Rod says this may be Pardosa lowriei, with no common name. Just like their namesake wolves, wolf spiders move fast, and they chase and pounce upon their prey. Some of their eyes are quite large, and, like Jumping Spiders, they have excellent vision. This female is carrying her egg sac on the beach at Indian Island. All spiders make a protective egg sac, and some, like this spider, carry their eggs attached to their spinnerets until they hatch.
7. Cross Orbweaver (Araneus diadematus) Spiderlings
The non-native European Cross Orbweavers like to build their webs outside our house and in the garden. One day I noticed hundreds of spiderlings on the side of our house, looking a bit like smiley faces or Pacman characters. After spider eggs hatch from their egg sac, the spiderlings disperse by walking or ballooning away. Just like snakes shed their skins and crabs molt to grow, spiders also need to molt about five to 10 times to reach their adult exoskeleton.
8. Clockwise: Funnel Weaver Spider Webs; Orb Spider Webs and Barbed Wire; & Sierra Dome Spider (Neriene litigiosa) Sheet Web
The New York Times’s Science Times recently ran a full page about “Spider Facts, Spider Fiction,” quoting researchers that “fears and misunderstandings about spiders abound in news reports.” In an effort to counter all the spider misinformation on the internet, Rod Crawford created a fun website called “Spider Myths”: https://www.burkemuseum.org/collections-and-research/biology/arachnology-and-entomology/spider-myths One of the general fallacies is that only orb or round spider webs are “normal.” Certainly, the famous Charlotte’s Web spider created an orb web, butwe can find funnel webs, sheet webs, and cobwebs, along with orb webs right here in Port Townsend.
9. Clockwise: Common House Spider (Parasteatoda tepidariorum) with Ant; Cross Orbweaver Spider Web with Five Insects; Sierra Dome Spider (Neriene litigiosa) with Pacific Dampwood Termite (Zootermopsis angusticollis)
Expert gardener and author Mary Robson is one of the hosts on KPTZ’s Nature Now. In her podcast #524, she discussed spiders with another master gardener. Mary said spiders are very helpful; worldwide they consume 440-880 million tons of insects a year. They help with pest control in gardens. Mary added that all spiders use spinnerets to make a liquid protein that creates a silk. Rod mentioned that only about half actually make webs, and the other half, like wolf, crab, and jumping spiders (described above) are active or passive hunters. Mary noted that spider silk is so strong and water resistant that scientists are studying it to adapt their characteristics for many purposes. But spider silk has yet to be produced in a lab.
10. Rufous Hummingbird with Spider Web
Another essential benefit of spider webs is their use by our beloved local hummingbirds to hold their nests together.
11. Gem-shaped Orbweaver (Araneus gemma) with Spider Wasp
Spiders can also be prey. Some spiders eat other spider species, and then there’s the spider wasp! One day hiking at Lake Crescent, my friend noticed a spider wasp hauling a Gem-shaped Orbweaver (Araneus gemma) all the way across the wide path. Don’t worry about spiders hurting you… you’re much more likely to be injured by dogs, farm animals, hornets, and wasps. Rod Crawford shared this reassuring information, “Neither black widows, nor any other species dangerous to humans, occurs at all (except for imported individuals) on the western Washington mainland. There are small black widow populations in especially dry climate enclaves on a few islands. On the mainland, one of our common house spiders is the false black widow Steatoda grossa, which is no danger to humans. Black widows do occur east of the Cascades, especially in the Columbia Basin.”
12. Clockwise: Sierra Dome Spider (Neriene litigiosa) Web; Sierra Dome Spider web (Neriene litigiosa) Close Up; Spider Web Colors #1 & #2
Finally, spider webs are amazing up close! Thanks to a physicist at the University of Illinois, I learned it’s “some sort of diffraction effect, with the apparent colors shifting around as the web bends in the wind.” He quoted a German physicist, “The colors are caused by interference of the rays scattered by the arrays of tiny sticky droplets on the catching threads,” and concludes, “apparently some types of spider deposit these tiny droplets in a very regular pattern.” If you find a ray of light shining on a spider web, and sit still with a macro lens, you can capture remarkable colors and patterns. A little breeze actually helps. The spiders might hide from you, but they never attack. It’s very peaceful.