I work in a world of spiders. Every few hours I'm distracted by a tiny movement in the periphery of my vision. It's a baby spider leaving home, dropping on its silken thread from the light fixture above me, bound on a slight current of air for a career in unknown territory.

My office, in the bottom storey of our house, is aboveground, with windows and plenty of light, but because bedrock protrudes into certain areas we call this level the basement. It's well-sealed, or so I thought, though an entire ecosystem of tiny creatures seems to be flourishing all round me.

Spiders, especially, live here in such amazing numbers that I can't help wondering how they sustain themselves. I've learned that the dominant species--the one hoping, perchance, to colonize the hairless expanse on top of my head--is a type of pholcid, or cellar spider. This family has 500 members worldwide and 35 in North America, all leggy, translucent, and pale; ours are likely Pholcus phalangioides, a common arachnid that came to this continent from Europe, hitchhiking with human hosts. Its untidy cobwebs, which clutter every corner and stretch in thin, lazy swaths across the ceiling, seem ephemeral until you try to remove them. Then their strength and stickiness become very evident. Abandon hope all ye who enter here.

At carpet level, numerous semihidden piles of body parts reveal the pholcids' favourite food. These dried-up husks are the remains of sow bugs, which also occupy my basement realm in startling numbers. Little grey guys, heavily armoured (though not heavily enough, it appears) with segmented shells, they trundle from place to place, living relics of the Paleozoic era. They are neither insect nor spider but crustacean, like crabs and lobsters: modern miniature trilobites that breathe with modified gills and serve as snacks for a host of Lilliputian predators. The cellar spiders on the ceiling must have different prey, though I can't imagine what, as few flying insects come this way.

Other spiders, however, pass by frequently. At least 20 arachnid species reside down here--giant and common house spiders, dwarf spiders, cobweb and funnel weavers--and I'm starting to suspect that they mostly survive by dining on each other. I don't bother them if they don't bother me. If they become bold, however, and crawl on me or try to take over my work surfaces, then I put them outside. After years in the basement, I'm comfortable handling creatures with eight legs and eight eyes. Most of B.C.'s spiders are harmless to humans, and I try not to kill them (though some, I admit, get sucked up by the vacuum in my rare and mostly futile attempts to reduce the cobwebs and organic debris).

The vast number of spiders that can sometimes be found in one small area fascinates zoologists. In Spiders of the World (Facts on File, 1984), Rod and Ken Preston-Mafham estimate that, at certain times of year, a typical hectare of undisturbed grassland could easily contain five million spiders, each one capable of eating an insect a day. In October 2002, scientists investigated a mysterious web covering a 25-hectare field east of McBride in B.C.'s Robson Valley. The top of the huge veil supported approximately five billion silk-laying spiders (two per square centimetre). Who knows what lurked beneath the surface? Brian Thair, a biology professor at the College of New Caledonia in Prince George, suggested to the local media that the spiders had found an unusual quantity of some nutritious prey. Residents speculated that the arachnid horde was trying to trap a flock of sheep.

There are about 20,000 species of "bugs" in B.C.; i.e., crustaceans, millipedes, centipedes, arachnids, and insects, the five classes that make up the "joint-legged", or arthropod, phylum. Many others await discovery. More than 35,000 different kinds of arachnids exist in the world, and approximately 3,000 in North America. According to Richard and Sydney Cannings in British Columbia: A Natural History (Greystone Books, 1996), there are at least 600 spider species in this province. All, write the Cannings, are "important predators on insects, yet we know surprisingly little about their distribution and ecology".

Although B.C.'s coastal spiders, including those that inhabit my basement, seem to be flourishing, the best arachnid habitats are found farther inland, where it's warmer in summer and rains less. Dry zones in B.C., for instance, support jumping spiders, cute little furry fellows with big eyes and an unnerving habit of leaping on prey from a distance. Another more widespread B.C. species is the fishing spider, which can walk on or beneath the water and even catch small fish. The western black widow, especially in the Okanagan Valley, is about the only spider in the province poisonous enough to really endanger a person.

Not all human visitors to our basement share my interest in spiders. This is where our guest quarters are located, and even though we thoroughly cleanse them of spider traces before hosting anyone, nocturnal screams sometimes filter up from below. Spiders do an admirable job for us of representing the unknown, and many people fear and loathe them. But an old English rhyme reflects a deeper understanding: If you wish to live and thrive, let a spider run alive.