Freedom of choice prevails in the vast arachnid world

Posted April 25, 2010, at 7:10 p.m.

There is probably a spider within three feet of you right now, while you’re reading. If it’s a wolf spider, it may be watching every move you make.
While we see hardly any of them, the truth is there are so many spiders that a biologist in Great Britain estimated about 2 million of them inhabit each acre of his farmland. About 175,000 spider species are thought to be crawling the planet as we speak, but only about 40,000 have been identified. Which means 135,000 kinds of spiders that have rarely or never been seen by human beings are industriously living, loving and spinning webs. They’ve been around for about 300 million years.
Recently biologists have been wondering whether animals — including spiders — have personalities. Anyone who has lived with cats or dogs knows pets have preferences and dispositions that include virtues such as loyalty and vices such as sloth. Why scientists should be surprised to learn that, I’m not sure, and I’m a little nervous about its taking them by surprise. I do know that our cat Brian is less rambunctious than his little common-law brother, Panda, and has a better sense of duty about protecting the grounds, and is less nitwitted, too. They’re different people, so to speak.
But spiders?
The scientists discovered in a recent study that spiders of the same species living in different places tend to have different behaviors. For example, funnel spiders living in grassland in New Mexico were found to be more aggressive and tougher than the same species of funnel spiders living along a river in Arizona. Not to over-anthropomorphize, but the New Mexico spiders were braver: They were consistently less quick to scurry back into the web when startled by a puff of air than the Arizona spiders were. They also beat up on each other worse over food than the Arizona spiders.
Now, the study did not account for the general observation that spiders do a lot of things that look suspiciously like intelligent acts. For one thing, weaving webs is a fairly complicated activity. A busy spider uses claws on its legs to work silk with the dexterity and precision of a knitter. And different species design different kinds of webs — orb webs, funnel webs and cobwebs — with different intricacies and even what appear to be adornments.
Some spiders conduct courtship rituals that imply they have preferences. Among nursery web spiders, the male catches a fly and offers it to a female he likes. If the female doesn’t like it — or him — she sends him away. Another male with a different fly might succeed, according to some kind of preference. Part of the strategy is to keep the female occupied eating the fly during mating, so she won’t eat him. But choose, she does.
Among spiders with good vision, such as wolf spiders and jumping spiders, the males pose and wave their legs and palps (roughly, hands) for the females, and apparently the best dancer gets the girl. Some rub body parts together to make sounds, like grasshoppers do, and you might cautiously point out that this at least appears to be a sort of singing, and to the female, at least, there are serenades more attractive to mating — or passion, or love? — and some less attractive, which is to say, better and worse.
Preferences, at least among humans, are matters of individual taste. And taste, as E.A. Poe observed, is our faculty for perceiving beauty. When a female spider prefers one male’s dance or fly to another’s, or stares down a puff of air, or adds a special twist of silk to the web, does she somehow understand that some things are better than others?
No one knows what kind of awareness the spiders have of all this. She certainly has no conscience, or moral sense — at least as Poe described it for humans: Some females will eat the males as soon as look at them.
It is a world worthy of Poe. What we see of it, anyway. Which is not much, fortunately. It makes me sort of nervous to think what it would be like to know the truth of what goes on in a spider’s mind as it decides whether to eat the fly or the suitor. Or watches you reading these words, three feet away.

 

naturalist@dwildepress.net

 

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