Types of Spiders: The Backyard Jungle Part IV

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Wolf spider.
Wolf spider.
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Jumping spider.
Jumping spider.
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The crab spider is a hunting spider. Learn to identify the types of spiders that benefit your garden.
The crab spider is a hunting spider. Learn to identify the types of spiders that benefit your garden.
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Orb weaver.
Orb weaver.

Few creatures are more misunderstood–or maligned–than spiders. Actually, of the 30,000-plus species of these purported people-poisoners, very few pose any real threat to humans. Rather, most types of spiders are extremely useful to us: Not only do they help preserve the delicate balance of nature, but they’re often among the first small predators to become active in eradicating pests from the spring garden plot.

Like other arachnids, a spider differs from an insect in that it has eight rather than six legs and two distinct body sections (as opposed to an insect’s three). It may not be much of a danger to you or me, but a spider’s a remarkably efficient killer machine when it comes to creatures of its own size. The two fangs mounted below its head are connected internally to venomous glands, enabling it to sedate and paralyze its prey immediately upon capture. Some spiders inject a digestive enzyme (which liquefies body tissues so that they can be easily ingested) directly into a victim’s body cavity, while others first crush their quarry and then cover its carcass with the substance. Either way, all that remains after the spider’s repast is an outer shell.

However, before dinner can begin, a victim must be caught . . . and many an eight-legged killer prepares by spinning a silken web from a liquid protein produced by a group of internal glands near the tip of its abdomen. As this fluid is pulled through the spinnerets (a cluster of external nozzles located near the anus), it hardens to form the prey-trapping net. The strands of the web may seem flimsy, but their tensile strength can be greater than steel filaments of the same diameter!

This silk is also used by spiders to fashion protective cocoons for their eggs and for wrapping up their prey. Perhaps its most fascinating use involves a behavior known as ballooning, a technique whereby arachnids can sail through the air for long distances on threads produced by their own bodies. (Young spiders disperse themselves to different areas this way.) To balloon, a spider stands on a lofty spot with its abdomen raised and squirts several strands of silk out into the atmosphere. These still-attached off -shoots serve as a parachute whereby a silk-spinner can hoist itself onto a passing breeze and journey several hundred feet in one bound.

At least 3,000 species of spiders are found throughout North America. To simplify matters, most of them can be divided into two categories, according to their predatory habits.

  • Published on Jan 1, 1984
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