Back in my footloose twenties, I lived for a year in Costa Rica, where I worked at a school in the central highlands and worked even harder, by reluctant necessity, at overcoming my lifelong horror of crawly things. Before the Costa Rican tourism board comes after me, I will say, in defense of that part of the world, that I have never lived anywhere else so ecologically magnificent. Every day, I commuted to work on a trail lined with ferns and bromeliads and the enchanted fortresses of strangler figs, while two-toed sloths lolled overhead and butterflies as big as greeting cards opened their dull-brown wings to reveal a blue as brilliant as the cloak of the Virgin Mary. At night, the moon cast shadows of avocado trees along the dirt roads, and the stars amassed in layers a billion deep. There were volcanoes, there were waterfalls, there were three kinds of monkeys, there was a dry season and a wet season and in between them an entire rainbow season, as if the local weather had been designed by Lisa Frank. On clear days, I would look out over verdant folds of mountains to where the sun glinted off the Pacific Ocean and reckon myself pretty much in paradise.
Still, there is a snake in every garden—though it was not the nation’s infamous pit vipers that scared me. Before taking the job, I had not appreciated the biological coördinates of Costa Rica: south of the Tropic of Cancer, north of the Tropic of Capricorn, right in the middle of the Arthropod Zone. Once I got there, however, this fact became appallingly unignorable. My roommates in my new house included ants that looked like “Star Wars” extras, beetles that looked like U.S. Army-issue vehicles, and scorpions that unfortunately looked exactly like scorpions and made themselves at home in my sock drawer. At night, mosquitoes gloated in my ear, and heavyset moths, furry enough to be mammals, and big enough, too, ricocheted around my bedroom walls, sounding like the opening scene of “Apocalypse Now.”
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All this I could have lived with, however unhappily. But I was completely, abjectly, characterologically, and possibly clinically unprepared to deal with the spiders. The scale of this problem made itself clear soon after I arrived, when I went to the kitchen to get a drink of water and—YAGGGRRHAAAAAHHHHHH! The creature in my sink was thick, hairy, hideous, Halloween-ready in its outfit of orange and black, and easily the size of my hand: as I later learned, a Costa Rican red-leg tarantula. That species is formally known as Megaphobema mesomelas, and if you guessed that the first part translates roughly as “gigantic and terrifying,” you’re right. This particular one had crawled into my sink from, I presume, the depths of our collective psyche, and looked like the result of a collaboration between Stephen King, Louise Bourgeois, and Hieronymus Bosch. I made a noise that must have been audible in Guatemala, leapt backward through the air a good six feet, and flattened myself against a wall.
What was I supposed to do? Like every self-respecting arachnophobe, I had spent my entire life prior to that moment making sure that I was never alone in a room with an arachnid—not even, say, a daddy longlegs, a perfectly harmless creature weighing perhaps a hundredth of an ounce. Now here I was, alone not only in a room but effectively in a nation, confronted by a quarter pound of spider flesh. Yet I couldn’t kill the creature, not because I had, in the moment, any ethical or sentimental objection to doing so but because I couldn’t think of a nearby weapon certain to do the trick. Plus, no way was I getting close enough to deal the fatal blow or, heaven forbid, hear the dying crunch of that enormous carapace. My feelings about spiders were the opposite of those old Wild West posters: I didn’t want them dead or alive. I didn’t even want them imaginary; I had been known to close books and flip over magazines to avoid having to see some particularly loathsome member of the order Araneae.
Perhaps you share this feeling. Perhaps you, too, have spent your life self-evacuating from rooms with suspiciously shaped cracks in the ceiling; perhaps even reading this is making your skin crawl. In that case, you will understand why I not only fled my house that day but seriously considered fleeing the country. What’s harder to understand is why, a couple of months ago, having long since left Costa Rica but having never left behind my intense arachnophobia, I decided to pick up a copy of “The Lives of Spiders” (Princeton), by Ximena Nelson, a professor of animal behavior at the University of Canterbury, New Zealand. What can I say? It was November; all around me, people were obsessively reading about things they feared and despised, in the hope that comprehension could lead to compassion and change. For my part, I figured I’d start small.
“The Lives of Spiders” is an unusual volume: part textbook, part encyclopedia, part coffee-table book for those whose taste in décor runs toward shabby eek. Its detailed scientific information is conveyed with endearing if not entirely contagious enthusiasm and accompanied by full-page photographs, which someone who is not me might possibly regard as beautiful. In addition to excurses on spider ecology, biology, and behavior, it contains miniature biographies of forty distinct species.
That is, I regret to report, a tiny fraction of the total number. To date, we know of some fifty thousand spider species, though, like this magazine, they are hard to keep up with, since new ones pile up every week. Scientists suspect the true number is at least double that, while the number of individual spiders likely clocks in somewhere north of fifteen quadrillion. These are not evenly distributed across ecosystems, of course, but you cannot escape them anywhere except Antarctica. Like us, spiders are geographically intrepid. They thrive across rain forests, cloud forests, boreal forests, grasslands, wetlands, deserts, savannas, steppes, caves, mountains, marshes, and bogs. One species, the diving-bell spider, builds its web beneath the surface of lakes and ponds, attaches an air bubble to it for breathing, and lives out its days underwater. Within these diverse environs, spiders distribute themselves the way Manhattanites do, crowding in at every level from garden apartment to penthouse. In your average patch of Eastern woodlands, there will be spiders burrowing beneath the soil, scuttling through the leaf litter, crouching in the bushes, dangling from the tree limbs, and spinning webs high up in the canopy. If your reaction to this is to vow to spend more time in the great indoors, you underestimate your nemesis; one recent study of private homes in North Carolina found spiders in one hundred per cent of them.
As you might expect of a zoological order capable of living anywhere from the Mongolian steppe to a ranch house in Fayetteville, spiders are remarkably diversified. They range in size from a hundredth of an inch to five inches across—and that’s just their bodies, because arachnologists, who clearly don’t think like the rest of us, generally do not include leg length when reporting the size of a spider. (To appreciate the psychological failure of this descriptive practice, consider the giant huntsman spider: technically an inch long, which is bad enough, but throw in the legs and the creature is a full foot from end to end.) Other characteristics vary just as widely. Some spiders live for less than a year, like mayflies, while others live for more than forty, like camels. Some have eight eyes, while others have none. Some female spiders lay a single egg, while others lay more than three thousand.
Still, there are some things that all spiders have in common, beyond their ability to make me levitate. Most obviously, they all belong to the class Arachnida, a spectacularly unlovable limb of the tree of life whose other members include scorpions, mites, and ticks. All Arachnida have eight legs (and, outside of the microscopic tardigrade, only Arachnida have eight legs; do not malign the wonderful octopus, which has eight arms). Also, all spiders are predators. There is one partial exception to this rule, Bagheera kiplingi, a largely herbivorous spider native to Mexico and Central America. Some other species will occasionally nibble on a plant, technically making them omnivores, but, on the whole, what distinguishes the spiderly appetite is its stunning carnivorousness. Collectively, spiders eat at least half a billion tons of meat per year, more than the amount consumed by human beings.
What exactly do these voracious flesh-eating creatures consume? Insects, of course. Also: fish, tadpoles, frogs, lizards, and the occasional vertebrate—mice, shrews, voles, bats. The largest spider, the Goliath birdeater tarantula, does, in fact, eat birds. One spider, Evarcha culicivora, which lives in Kenya and Uganda, feeds almost entirely on us, although, thank goodness, indirectly: its preferred diet is mosquitoes engorged with human blood.
Another thing spiders eat with great gusto is one another. Every known variety of spider can engage in cannibalism, and some do so with particular enthusiasm, most often during or immediately after copulation, with the female almost always doing the eating. Up to eighty per cent of male wasp spiders, for instance, get eaten during their first attempt at mating, and some male widow spiders, apparently resigned to their fate, deliberately flip themselves over after sex in order to be consumed. Male dark fishing spiders, meanwhile, die spontaneously during sex, saving the females the trouble of killing them prior to dinner. In some species, a female spider will let herself be devoured by her spiderlings, a behavior known as suicidal maternal care. Then, there are the many spiders that simply stalk their fellow-arachnids, killing and eating them as ruthlessly as if they were no more closely related than we are to turkeys and tuna.
If I were a spider, in short, I would still be afraid of spiders. As an order, they possess a whole suite of lethal characteristics and abilities, capable of ambushing, snaring, swarming, or deceiving their prey. To these ends, they are equipped with more cognitive dexterity than you might imagine, plus tooth-like structures, tarsal claws, and fangs, which, in the magnified images in Nelson’s book, look like they could belong to, respectively, great white sharks, jaguars, and Carmilla. But the most effective weapons of the spider, not to mention the ones most central to its fearsome reputation, are the arachnid equivalents of the iron fist in the velvet glove: venom and silk.
Whatever your feelings about spiders, spider silk is an astonishing material. Although a strand of it is far skinnier than a human hair, it has more tensile strength than steel and can absorb more impact than Kevlar. That’s partly because it’s also extremely ductile, meaning it can stretch many times its normal length before breaking, which is why a bird can fly straight into a web without destroying it. Conveniently for spiders, silk also super-contracts when wet. Subject it to a good rainstorm and, no matter how much it has been stretched and strained, it will return to its original condition.
This ultra-tough material starts out as a liquid, stored in glands in the spider’s abdomen. From there, it flows into organs called spinnerets, of which a spider may have up to eight, “each ending in tiny spigots,” as Nelson writes. The spider then extrudes the silk manually, so to speak, pulling it out of a spinneret with its hind legs and thereby realigning the protein molecules so that the formerly liquid substance turns solid. Whether you regard this as evidence of the awesome inventiveness of nature or of the deeply alien creepiness of spiders is a matter of perspective.
Either way, the number of things that spiders can do with their silk would impress even E. B. White. Most obviously, they can use it to build webs, which range in size from half an inch in diameter to thirty square feet and in sophistication from simple triangles to elaborate spirals and funnels. Because webs co-evolved with insects, and therefore with the rise of insect flight, they can be found not only stretched across ground cover and rocks but also in vertical sheets that can sometimes span entire rivers. For reasons that remain somewhat mysterious, certain spider species decorate their webs with bits of plant matter or the mutilated remains of victims, like Charles II hanging the head of Oliver Cromwell on Westminster Hall. Others decorate with the silk itself, the most famous and enigmatic example being the St. Andrew’s Cross spider, which weaves a cross into the center of its web.
Although we think of webs as a defining feature of spiderhood, only about half the species build them, yet all spiders produce silk. Its many other uses include a dispersal method known as ballooning, in which spiders, typically young ones, climb up something tall, point their bellies skyward, and release lines of silk that form a parachute and carry them off in the breeze. Spiders have been known to travel hundreds of miles this way, sometimes landing on ships in the middle of the ocean. They also use silk to line their nests, to build cocoons for their eggs, and to subdue their prey. Burrowing spiders stretch silken trip lines outside their homes, to alert them to the presence of predators or dinner; jumping spiders establish safety lines prior to leaping across a landscape, like rock climbers adding anchors while ascending a cliff; widow spiders drop a line of silk from their webs and essentially go fishing; bolas spiders swing a line of silk overhead and lasso their prey. Male spiders, which use one organ to produce sperm and a different organ to copulate, make little silk purses in which they deposit their semen before transferring it to the necessary body part prior to mating.
These various uses require different kinds of silk, which are made in different glands. To build the classic orb web, for instance, spiders use four kinds of silk: one for the frame and radial threads; another for the scaffolding that’s used during construction, then often removed when the web is complete; a third to anchor the web to fixed surfaces; and a fourth to create the spiral-shaped “capture zone” in the center. Should something delectable stumble into this zone, it will swiftly find itself encased, like a foil-wrapped falafel sandwich from a food cart, in yet a fifth kind of silk.
You might imagine, based on this, that a web is a kind of biological mousetrap, but it is far more sophisticated than that, and better understood as an externalized sensory system. Most spiders can see, thanks to their excess of eyes, and some have exceptionally acute vision. But none of them have ears or even antennae, as insects do. Instead, the web itself functions like an antenna, picking up and amplifying sounds from as far away as thirty feet, Nelson writes. Scientists suspect that spiders can effectively “hear” these sounds as the waves propagate to them through the web.
The ability of spiders to detect information via their webs is thanks to another crucial but icky arachnid feature: hairiness. Much like the hairs in your inner ears, the hairs—technically, sensilla—on a spider’s legs stir in response to vibrations, such as those created when something bumbles into a strand of silk. These vibrations help the spider determine the size and the location of its victim, and, as their frequency and amplitude change, the spider can determine something else, too: when the struggling creature is exhausted enough that it is safe to approach. That’s where the venom comes in.
I am sorry to say that almost all spiders are venomous. In fact, if a creature is venomous, odds are good that it’s a spider; according to Nelson, there are more venomous spiders than there are venomous animals of all other kinds combined. Wandering spiders—those that don’t build webs—rely on venom to attack prey, whereas web-building spiders use venom and silk together. Among these web-builders, some varieties tend to bite their prey first and wrap it in silk afterward. Others wrap first, rotating their victim as if on a spit while pulling sheets of silk around it; only when it is immobilized do they inject it with venom.
There are many variations on this basic practice, including some species that—in the spider equivalent of patting the head while rubbing the stomach—manage to bite and wrap at the same time. Perhaps the most impressive version is that of the pale spitting spider, whose name derives from its unusual capacity to eject a particularly gluey form of silk not from its spinnerets but from its fangs. Upon encountering a potential meal, it sprays a vast quantity of this goo all over it, a process that takes less than a millisecond. In addition to being supremely sticky, this specialized fang silk dramatically contracts on contact, leaving the victim essentially shrink-wrapped. Once that’s accomplished, the spider approaches and bites the creature; this time, what emerges from its fangs is venom.
How much venom that spider or any other uses is a matter of spiderly discretion. A creature that is especially large or especially feisty will get a bigger dose; one that is smaller or already exhausted will get a smaller one, or even none at all—a so-called dry bite, a kind of spider psych-out reserved for prey that is basically harmless. Remarkably, spiders can control not only how much venom they use but also what kind: because venom glands and ducts have separate sections containing different toxins, spiders can customize their output for different prey, thereby designing the maximally debilitating cocktail on the spot.
Unfortunately for spider victims everywhere, that venom, no matter how bespoke or abundant it might be, is seldom lethal. In most cases, it paralyzes rather than kills, whereupon the spider vomits a bunch of extremely potent digestive fluid on top of its future dinner. In other words, like some of its sensory systems, the spider’s digestive system is externalized: it takes place not in the spider’s belly but in the prey itself, where the regurgitated enzymes break down the creature’s soft tissue, effectively puréeing it alive. Once that process is complete, the spider sucks up the liquid results, leaving any indigestible material behind.
Given the gruesomeness of arachnid eating habits, it might seem reasonable to worry about a spider turning its pointy, poison-dripping fangs on us. Far be it from me to question the legitimacy of any spider-based phobia, but I am duty bound to report that the fear of their bites is largely ungrounded: fewer than 0.5 per cent of spider species possess venom that is toxic to humans. Although Nelson is generally in the business of doing P.R. for the spider community, she helpfully provides a complete list of the offenders: recluse spiders (found in warm regions around the world), sand spiders (found in deserts in Africa and the Americas), Brazilian wandering spiders (found in Central and South America), mouse spiders (found in Chile and Australia), Australian funnel-web spiders (found only in Australia), Poecilotheria tarantulas (found in India and Sri Lanka, not in Costa Rican kitchens), and widow spiders (found pretty much everywhere).
Of these, perhaps the most dangerous are the Australian funnel-web spiders—especially the Sydney funnel-web spider, not because it is more venomous than other members of its family but because it lives in close proximity to five and a half million people. Aggressive when attacked (say, by an unsuspecting foot sliding into an occupied shoe), funnel-web spiders will sometimes bite repeatedly, with fangs allegedly capable of penetrating toenails. Their venom, although not lethal to most vertebrates, is deadly to primates; a two-day-old mouse can withstand nearly ten times the dose that will all but instantly kill a macaque.
Happily for Aussies, there’s an antivenom for funnel-web-spider bites, and there have been no documented deaths from them since it was introduced, in 1981. There’s also an antivenom for widow spiders, whose venom contains a neurotoxin that can cause muscle spasms, sweating, and tachycardia, but it is rarely used and scarcely necessary. Unlike funnel-web spiders, widow spiders are not particularly aggressive and often deliver dry bites. According to Nelson, fewer than half of people bitten show any symptoms, and under two per cent have severe ones. No one in the United States is known to have died of a black-widow bite in at least forty years.
For my money, the most alarming venomous spider is the brown recluse, even though it is a mild-mannered creature that generally cohabits harmlessly with humans. To provoke it into biting, you must be the aggressor, even if accidentally—say, by rolling over on it while you’re sleeping. Even if it does respond by biting you, the bites are often dry and the symptoms mostly minor. In a small number of cases, however, a recluse bite causes necrosis of human tissue; in an even smaller number, typically involving young children, it can be fatal. What makes this especially scary is that, unlike for widow and funnel-web bites, there is no known cure.
Before you call the exterminator, however, consider these reassuring figures: worldwide, somewhere between three and seven people die of spider bites each year, putting the odds of meeting your maker that way at significantly worse than one in a billion. That doesn’t prevent people from routinely showing up in emergency rooms seeking help for spider bites, ninety to ninety-six per cent of which turn out not to be spider bites at all. The brown recluse is routinely blamed for bites that occur in places where the species has never been found. Other species have faced similar character assassinations. Wolf spiders are terrifying-looking, with enormous bodies and long, thick legs, but the antivenom developed for their bites and used for decades turns out to be unnecessary, because their venom is not toxic to humans.
One might reasonably wonder: If spiders almost never cause us real harm, why are so many people afraid of them? Between three and fifteen per cent of the population suffers from full-blown arachnophobia, making it not only one of the most common animal phobias but one of the most common phobias over all, up there with heights and flying and ahead of needles and crowded places. Those numbers do not reflect the far larger share of people whose aversion to spiders does not quite rise to the level of pathology.
The source of this broad anti-arachnid sentiment seems unlikely to be evolutionary. For one thing, arachnophobia is prevalent in places with no dangerous spider species whatsoever; for another, even before modern medical interventions, spiders did not pose a significant threat to human beings. If anything, they are good for our health, since they carry no known diseases but are voracious consumers of insects that do, including tsetse flies and malarial mosquitoes. In fact, the strongest evolutionary case for arachnophobia rests on the dangers not of spiders but of scorpions, the theory being that we generalized a reasonable fear of those creatures into a fear of their classmates, so to speak. It’s true that roughly twenty-five per cent of scorpion species are toxic to humans, and, even with antivenoms, their stings kill some three thousand people a year. The problem is that scorpions and spiders don’t actually look very much alike; by the same logic, we should all be afraid of moths based on their similarity, such as it is, to hornets.
And there’s another problem with this theory. If concern for our safety were the main driver of phobias, we would all be considerably more scared of dogs, lions, elephants, and hippopotamuses. But, of course, we are not—and as I read Nelson’s book it occurred to me for the first time that my fear of spiders exists in the absolute absence of any fear that I’ll be bitten. I suppose that’s what makes it a phobia: a fear uninformed, and unassuaged, by rationality.
Wherever we might look for the origins of arachnophobia, then, it’s not in the land of reason. It’s in what you might call the land of oog: something about spiders just weirds us out. The nature writer David Quammen, grappling with humanity’s widespread fear of spiders and snakes, once floated what you might call the “too many or too few” theory: both creatures, he wrote, defy the “range of legginess that’s standard for most of the animal kingdom—namely, four legs give or take two.” He then dismissed the idea, since, if it were correct, people would also be terrified of oysters, which have no legs, and lobsters, which have ten. Yet I believe there’s something to it. Survey arachnophobes and you will learn that one of the things we find most disturbing about spiders is how they move: uncannily, unpredictably, and incredibly fast (not to mention up walls and across ceilings). As it happens, this aversion is grounded in a fascinating physical reality: spiders move differently than virtually every other animal on the planet, relying not on muscles but on a built-in hydraulic system.
I suspect that this is the key to why so many of us find spiders creepy: it’s not their legs, per se, but the fact that they are dramatically unlike us in almost every respect. Consider their eyes, which are as round and globular as fish eggs, often disproportionately large (but not in the dewy, Walt Disney way), variable in size even on the same spider, and arranged in such bizarre ways that it’s hard for our brains to even parse them as eyes, let alone determine where the spider is looking, to say nothing of what it is thinking. Consider, too, their penchant for postcoital cannibalism. Consider their disgusting table manners and their grisly practice of wrapping their prey in winding sheets. What with one thing and another, spiders are all but indistinguishable from the countless horror-movie creatures they have inspired.
On top of this, and speaking of horror movies, spiders suffer from terrible reputation management. Their depictions in literature, film, and folklore run a short gamut from icky to deadly, and the small handful of exceptions aren’t potent enough to tip the balance. For every Charlotte, there are a hundred Little Miss Muffets; for every Itsy Bitsy, a thousand Aragogs. What’s worse, their depiction in real life is almost as bad. This is an order of animals whose named members include the ogre-faced spider, the assassin spider, the skull spider, the ghost spider, the goblin spider, the vampire spider, and a recently discovered species from Sri Lanka known in Latin as Poecilotheria rajaei and colloquially as the face-sized tarantula.
What’s to love, then? Lots, Nelson insists. Quash your native repugnance, she advises us, and consider the astonishing things that spiders can do. Colonus puerperus, found throughout the American South and Midwest, can jump almost forty times its body length, or six times farther, relatively speaking, than my heretofore impressive house cats. The flic-flac huntsman spider, native to Morocco, can double its running speed by turning cartwheels over the local sand dunes. Even the humble daddy longlegs has a trick up its eight sleeves: when threatened, it spins at such high speeds that it turns into a blur, making it almost impossible for a predator to attack it. The hairs on the legs of the tiger bromeliad spider look alarming, but Nelson writes that they may be the most refined sensory organ known to science, able to respond “to one hundredth of the energy contained in a single photon of green light!”
The exclamation point is hers, but by the end of the book I could no longer begrudge it. In addition to making the case for individual species like these, Nelson argues for a new understanding of the order as a whole. Long maligned not only as creepy but as dim-witted and instinct-driven, spiders turn out to be capable of learning, decision-making, sophisticated navigation, even number recognition. Moreover, the very features that make them most alien to us also make them potentially advantageous. Engineers are studying the unusual mechanics of spider motion to create both robots and human prosthetics; optics designers are looking to spiders’ visual systems to supply ever-smaller lenses with depth of focus and high resolution; and everyone from biomedical researchers to material scientists is trying to synthesize spider silk, given its unparalleled combination of lightness, toughness, and elasticity. Add to all this the environmental case for spiders, which are crucial members of almost every ecosystem on earth yet are drastically underrepresented on endangered-species lists, presumably because they are widely regarded as what you might call repulsive microfauna.
Finally, there is the existential case for spiders: the idea that their fate is somehow bound up with our own, not only ecologically but emotionally, psychologically, and spiritually. I am not thinking here of that fiery theologian Jonathan Edwards, although he was a huge admirer of spiders, writing a thesis on them in his youth and using them, in the most famous sermon he ever delivered, as stand-ins for unsaved souls. I am thinking, instead, of Walt Whitman, who, in a more generous gloss on the Calvinist take, watched a spider exploring its surroundings by launching “filament, filament, filament, out of itself” and saw in that behavior our own perilous and hopeful situation: how we cast out into the vast unknown, “till the bridge you need be form’d, till the ductile anchor hold / till the gossamer thread you fling catch somewhere.”
It’s humbling to see a creature I’ve always reviled rendered so beautifully; humbling, too, to be reminded of what none of us should ever forget, that reflexively hating anything alien to us is the beginning of evil. That is not just a lesson about spiders, of course. Whitman, in his unbounded adoration of everything, also managed to love humanity, both for our wonderful strangeness and in spite of our own infinite varieties of hideousness. ♦
An earlier version of this article misstated the amount of meat consumed annually by spiders.
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