They are the stuff of nightmares for many people - but spiders feed on our household pests.
Lurking, stalking, waiting in webs ready to pounce... spiders inspire fear like few other animals. Rob Dunn confronts our eight-legged demons.
It’s one of the oldest stories. The dark forest, pregnant with possibilities, began as a kind of Eden. Each tender green cell grew unbothered by animals and subject only to the laws of physics, growth and competition.
Then, slowly, the animals began to creep onto the shores. They were not yet sophisticated. They moved awkwardly among the acres of unprotected shoots.
And then everything changed. Predators came ashore and began to lay waste, eating the defenceless herbivores one by one. Eden was lost. The spider monsters had arrived, with their hairy legs, rows of huge, goggling eyes and wicked, sharp fangs.
We see these fiends now in our gardens and bath tubs, and under our sofas. We glimpse them spinning their webs or waiting. We refer to the way they hide in dark corners as lurking – but we might as well call it spidering.
Invasion of the body snatchers
Four hundred and sixteen million years ago, in the Devonian Period, spiders were already spinning silk. This was long before the first reptiles had evolved, much less mammals.
By the Cretaceous Period (144 million years ago), some species had begun to weave webs in which they captured the first flies, bees and beetles. In 2006, Enrique Peñalver at the American Museum of Natural History
found a 110-million-year-old piece of amber in which a spider
and part of its web were entombed. Trapped in the silk was a fly.
From these beginnings, spiders have diversified. Some can swim. Others fly on silk parachutes. Still others swing balls of silk towards moths that they attract with the smell of sex. But no spider ever evolved the ability to eat leaves – or anything other than animals, really. They say no to plants; no, even, to dead animals.
Spiders invented most of the ways of killing. They were the first ambushing leopards, the first stalking lions, the first wolves and the first to adopt a dozen other modes of predation that mammals had yet to invent. There may be hundreds of thousands of species of spiders on Earth, living hundreds of thousands of different, deadly, lives.
Maybe there are even more. The naming of spiders is more undone than done. New species await description not only in the Amazon, but also in basements and back yards. The spider looking at you from under your bed might not yet have a name.
Clearly, part of the trouble with knowing spiders is that we are afraid of them. Okay, maybe you aren’t, but you probably know someone who is. A recent study found spiders to be the animal most frequently cited as feared.
Many adults are afraid of spiders. Many children are afraid of spiders. Show a pre-verbal child a picture of a spider and a fly and they will often focus anxiously on the spider.
Spiders on film
Culture, and horror films in particular, undoubtedly influences our fear of spiders. Because not everyone shares the aversion. In the Philippines, Japan and Singapore, they’re kept as pets, whether for observation or to be used in spider fights.
In Papua New Guinea, spiders are eaten with great relish (and a little salt). To the Hopi, a Native American tribe, spiders are implicated in the origin of the universe. Yet arachnophobia seems prevalent enough to deserve more of an explanation.
Psychologists have suggested that we fear spiders because those of our ancestors who were insufficiently wary of them died of spider bites. But psychologists seem to have failed to ask whether spiders kill people, or at least whether they kill enough people for natural selection to favour the wary over the brave.
You may be conjuring up mental images of the deadliest spiders on Earth right now. Black widow. Redback spider. Bird-eating tarantula. “They are killers,” you might be thinking. And you would be right – sort of.
The truth is that, though spiders are often deadly (to their prey), accounts of bites on humans are greatly exaggerated. Richard Vetter of the University of California examined reports of attacks by brown recluse spiders in the states of California, Washington, Oregon and Colorado.
He and his colleagues documented 216 cases of bites attributed to brown recluses in just over three years, but only six of the bites were actually in places where the species is found. Vetter has revealed similar levels of misdiagnosis in Florida, the UK, Australia and nearly everywhere else he has looked.