How much do you know about spiders? The superhero Spider-Man is awesome, but the role of actual spiders in diverse ecosystems around the world is just as captivating.
“If spiders disappeared, we would face famine,” declares Norman Platnick, who studies arachnids at New York’s American Museum of Natural History, where a live spider exhibit opened in July. “Spiders are primary controllers of insects. Without spiders, all of our crops would be consumed by those pests.”
Just to clarify: although insects and spiders are often grouped together, they belong to different animal groups. Spiders are arachnids – technically Class Arachnida, which includes ticks, mites, and scorpions. The most obvious way to distinguish insects from spiders is to count their legs. Insects have six legs, while arachnids have eight.
The importance of spiders to agriculture may be well known, but did you know that the spiders on one acre of woodland alone consume more than 80 pounds of insects each year? Clearly, those insect populations would explode without their spider predators.
That’s what Platnick is talking about.
Aside from chemical control, predation is the only way to limit herbivorous pests. And spiders are excellent at this task. Spiders are particularly crucial in organic farming, which relies heavily on biological pest control.
A few more fascinating facts about spiders:
* Spiders were around more than 300 million years ago, long before dinosaurs walked the Earth.
* Only about 50 percent of known spider species make webs. Others hunt their prey or burrow underground.
* You are unlikely to be bitten by a spider, since they are very shy. They generally prefer to run away rather than bite.
Scientists are also exploring other ways in which spiders could be helpful to humans. That’s because a spider’s venom contains hundreds of different chemical compounds, some of which may be medically active.
So researchers are testing many of these chemicals. At Yale, scientists are examining whether chemicals in the venom of the Australian funnel-web spider could be used to improve pain-control medications. At the University of Buffalo, a researcher is working on healing muscular dystrophy patients with a compound in the venom of a South American spider. In Seattle, a doctor is working on a project that involves a scorpion-venom concoction that makes brain tumors glow.
Then of course there is spider silk: spiders make many different kinds of silk in their webs, each with a property, such as toughness, flexibility, stickiness. Perhaps this too could have important uses in the future.
There are indeed many unknowns about spiders.
“Scientists have identified almost 45,000 different spider species,” says Platnick, “and that’s at best one-half of what actually exists. When we lose a spider species, we may lose a compound that could have cured epilepsy. We may lose a silk that could have produced a strong and lightweight material.”
But Platnick is most concerned about the vital importance of spiders to agriculture since, like many animals, spiders are threatened by habitat loss and fragmentation of habitat, as well as by introduced species. Spiders may often be overlooked in conservation planning, just because they are so small.
That is a huge mistake, Platnick believes. For him, it is quite simple: without spiders, our crops will be eaten by insects and we humans will starve.
Spiders have been fascinating writers for a long time: remember Shelob, Tolkien’s giant evil spider in “The Lord of the Rings”? Or E.B. White’s Charlotte the spider?
So look kindly on the next spider you see; our future depends on these eight-legged creatures.
Photo Credit: Thinkstock
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