With Halloween less than a week away, black plastic spiders enmeshed in synthetic webbing have crept into neighborhoods and grocery stores.
Yet the explosion of spiders this time of year is about much more than their association with the spooky holiday tradition. Fall is the main event for most spiders. This is the time when we see spider webs in nature sparkling with dew and laden with egg sacs. We see glimmers of gossamer silk on the breeze, carrying young spiders to new homes. We find congregations of cellar spiders in the corners of our showers, kitchens and living rooms. And, as those of us who weep at the end E. B. White’s classic Charlotte’s Web know all too well, fall is the end of life for many beloved spiders.
It is tempting to divide humans into two camps: those who hate spiders (squishers) and those who admire them (carrying them outside in a jar or paper towel). There also is a growing contingent of humans, personified my colleague and winner of Wildcare’s 2017 Terwilliger Environmental Award Gwen Heistand, who absolutely loves all things creepy and crawly. Gwen will adjust her own lifestyle to accommodate the spiders that show up on her window sills and doorways.
“I don’t open that door at all any more,” she explains, pointing to a door in her kitchen ensnared in a complex of spider webs and their egg sacs. What I have found, and what Gwen has taught me, is that with even just a little bit knowledge, most of us can become spider lovers.
Spiders are literally everywhere: on beaches, under rocks, in the soil, ballooning in the upper atmosphere, in the canopy of trees, and of course in our homes, especially, it seems, in our showers. While all spiders make silk, and all spiders are carnivores, not all spiders weave webs. The classic circular spider web is made by a group of spiders called orb weavers. Another group, called sheet web weavers build dense filmy structures sometimes shaped like funnels, domes, or even cups and saucers to trap their prey. Our common wolf spiders, on the other hand, chase down their prey on foot, using silk primarily to construct their protective egg sacks and attract a mate. Burrowing spiders like false tarantulas and turret spiders line their tunnels and towers in silk, with the dual purpose of providing stability and alerting the spider when prey or danger is near.
Depending on the species, a single spider can make up to seven different kinds of silk, each with its own purpose. Spider silk starts as a liquid protein produced by special glands and then extruded through tiny spigots in the spinnerets located on the underside of the spider’s abdomen. Dragline, or ampulate, silk is the strongest; only a few microns in diameter, it is stronger per unit weight than steel. Used as a tether, dragline silk allows spiders to rappel out of danger or just to get from one place to another. Orb weavers use this type of silk to frame their webs and then another stretchy spiral-capture silk to weave the net that snares unwary insects. Tough swathing silk is used to wrap struggling prey while a softer cocoon silk forms the cozy and protective egg sac.
Indeed, each of these of the unique materials are spectacular feats of engineering that humans are only now coming to understand. “Spiders have so much to teach us,” insists Heistand, who points out that for years, scientists have been trying to unravel the mysteries of spider silk to adapt to human uses. For example, orb weavers use silk that reflects ultraviolet light, in part to prevent birds from crashing into and destroying the web. Inspired by this idea, a company has recently incorporated an invisible (to humans) “web” of U.V. reflective film into glass. Just as spider silk warns birds away from webs, this new “bird-friendly” glass warns them away from windows. The hope is to reduce the hundreds of millions of birds killed by collisions with window glass every year. The properties of spider silk also are being studied for a range of mind-blowing applications in construction and medicine. Imagine flexible bridge suspension cables, super-strong bungee cords, or even delicate scaffolding for organ replacements.