With Halloween behind us, spiders might not be as present in our minds as when we decorated our homes with fabricated webs and plastic creepy crawlers. But they’re still here. They’re always here.
While we might think that a chill in the air signals spiders to come indoors, spiders are most likely already residents inside. The spiders that do live outdoors often remain there, being the cold-blooded creatures that they are, to simply hide in leaf litter, soil, woodpiles, or beneath rocks.
Another popular myth to be dispelled is that spiders are insects. Nope. Spiders fall under the class of Arachnida, while insects belong to the class Insecta. Spiders have two body regions, eight simple eyes, no antennae, no wings, four pairs of legs, and an unsegmented abdomen. Insects, on the other hand, have three body regions, two compound eyes, two antennae, four wings (although some may have two or even none), three pairs of legs, and a segmented abdomen.
A third common misconception is that most spiders are venomous. Nearly all spiders have venom; however, out of 50,000 species (a low estimate, as experts believe the number could be far greater), a mere 30 to 50 species are exceedingly toxic to humans.
When it comes to spiders, I must confess that I’m that person — the one who hurriedly grabs a water glass and a piece of paper to capture a house spider and free it outside. Not that I don’t want to sometimes crush one, but killing just isn’t my nature. The only purpose of my gracious emancipation is to free the creepy crawlers from the indoors, my indoors, quickly! But I wonder, with my arachnophobia (the fear of spiders), if I might consider their temporary water glass detention an educational moment. I am, after all, extremely fascinated by their web making.
My education started with getting acquainted with a few spiders living in the Sierra.
In The Laws Field Guide to the Sierra Nevada, author and naturalist John Muir Laws separates 36 spiders into five categories according to their web-weaving styles: orb webs (garden spiders), tangled cobwebs (western black widow, false widow, cobweb weaver), sheet webs (hammock spider), running and burrowing spiders (large wolf spider), and lastly, jumping and crab spiders (running crab spider and jumping spider). For each group, Laws shares an interesting fact. For example, orb web spiders, he writes, reconstruct their webs on a daily basis. Wolf spiders run down small insects rather than spin webs. Jumping spiders have very large, forward-facing eyes that provide 3D vision.
The Harvestmen — more commonly known as daddy longlegs — are not classified as true spiders but are closely related. They are easily recognizable by their extremely long, thin legs, and seek corners next to light fixtures where the light is good for catching prey.
Noticeably, Laws’ categorization of web styles reveals that a spider can be identified simply by its web design. Of course, webs also compound the importance of web building, mainly for capturing prey, which leads me to answer my paramount questions like: How do spiders make a web? How does a spider thread reach from one side of a street to the other? For an elementary explanation of an orb web, I searched the internet’s information and numerous videos and spoke with Jason Bond, an evolutionary biologist and taxonomist at U.C. Davis, and Andrew Gordus, assistant professor of biology at Johns Hopkins University. Gordus, renowned for his work on orb weavers using infrared illumination and special cameras to document spider web-making, only became interested in webs seven years ago after stopping to observe one in Central Park. Like me, he wanted to know how they did it. Now, his research is all-consuming.
1. Producing and Pulling
Under a spider’s abdomen lies her (mostly females spin webs) silk-spinning glands, called spinnerets. These glands secrete silks, which are composed of rich protein building blocks — amino acids. Within the amino acids is the code that defines each silk gland’s function (with different types of silk) for either the web or an activity, such as making an egg sack, creating a drag line to make the frame and radius of the web, or creating a sticky capture line. There are at least seven different silk glands in orb weavers.
In the gland, the protein begins as a liquid gel. As the chain of protein passes through the silk duct, like streaming through a narrow tunnel, the liquid is solidified.
At the end of each spinneret is a group of nozzle-like structures from which, like at the ends of hoses, a strand of silk comes out of each hole. As the spider pulls at the silk from the spigots with its claws (web-spinning spiders have three claws on each leg), the molecules are stretched out and linked together. According to a 2018 Science Magazine article, most spider silk is five times stronger than steel, and each silk fiber is composed of parallel strands, like a cable, called nanostrands.
Once airborne, the thread wavers in the wind, a process called kiting or ballooning.
The spider waits until a breeze takes up the thread and the thread attaches itself to an anchor point. Afterward, she walks across the silken bridge, like slacklining.
From the primary slackline (bridge line) of point A to point B, the spider descends on a looser thread, as if repelling — from the approximate center — which she’ll attach to the ground or an object. This forms a Y shape. Back up she returns to secure radial threads that create a triangle frame from which to create the more in-depth web.
The spider then starts to create the larger circular net by attaching segment-by-segment of more threads, like crocheting one thread to another.
6. Applying Glue
Lastly, the spider uses the initial spiral configuration, the auxiliary spiral, as a guide to create the “catching spiral,” ejecting the “capture thread,” which it dots with glue. (Under a microscope, orb-weaver glue looks like spaced-out beads on a string.) As the catching spiral is made, the auxiliary spiral is taken down, much like scaffolding being removed Along comes its prey — flies, mosquitos, moths, and bees — with little hope of detaching from the tacky glue substance. But, why doesn’t the spider get stuck in its own web? Spiders navigate with the tips of their legs — their tiny hooked claws — so there is little contact area touching the web.
Studies have shown that spiders consistently repair damages, restoring the structure of the webs by re-establishing the tension in the radial threads, and/or adding new threads when anchors or frames break.
Many orb-weaving spiders recycle their webs by eating the protein-enriched silk. Only the main thread of the web is left intact. The next morning, the spider will weave another web.
9. Blind Ambition
Even more remarkable is the fact that spiders build their webs blindly. Because their eyes are located at the top of their heads and their legs are located below them, they basically can’t see what they’re doing. Plus, most spiders build webs in the dark of the night. Only by memory of space, what’s situated around them, are they able to create their snares, much as if we were blind but could make our way around our living rooms, knowing where our furniture is placed.
It’s a simple explanation to a complicated process, but it’s a start to understanding one of nature’s natural builders. Countless times have I looked at a spider’s web and appreciated the design yet had no idea of the engineering behind the artistry. Just as we catch many a sea creature with nets, the spider captures its meal with a skillfully knitted web. How? Amazingly, spiders have their own integrated construction materials and manufacturing know-how. Nature is smart that way, and this is one example.