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Super-powered spiders

Web-slinging and wall-crawling come naturally to these bug hunters

By Pamela S. Turner / May 28, 2002

Darrell Ubick bends over a square of canvas, picking carefully through oak leaves, dried moss, and bark pieces. An itsy-bitsy spider tries to sneak away, but Mr. Ubick spots its tiny, ghostly-green body. This particular spider is found only in oak trees along the California coast.

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"As a kid," says Mr. Ubick, "I always liked spiders and insects." By sucking on one end of a tube draped around his neck, he plucks the miniature spider off the canvas. "There is a mesh inside the tube," he explains, "so I never get a spider down my throat. He gently blows the spider into a glass vial.

Creeping, crawling carnivores

The first thing to know about spiders is that they are not insects. Insects have six legs, spiders have eight. Unlike most insects, spiders don't have wings or antennae. Like scorpions, mites, and ticks, spiders are "arachnids" (uh-RAK-nids). This group of creatures gets its name from Arachne (uh-RAK-nee), a beautiful Greek maiden. According to legend, Arachne made the mistake of beating the goddess Minerva in a weaving competition. In revenge, Minerva turned Arachne into a web-weaving spider.

Scientists have named 40,000 kinds of spiders. (There are only about 4,000 kinds of mammals.) At the California Academy of Sciences in San Francisco, where Darrell Ubick works, 9 million insects and spiders are preserved in trays and glass vials.

"Scientists would love to identify all the different types of spiders," Ubick says. He has discovered about 30 new spider species himself. "But it will take a long time. We probably only know about half of all species, and even California has many spiders we don't know much about."

Spiders are nature's bug hunters. "Carnivore" makes us think of wolves and tigers, but spiders are probably the most common carnivores on land.

Just as lions and eagles hunt in different ways, so do different types of spiders. Crab spiders lie in wait, ambushing their prey with a lightning-fast strike. Jumping spiders stalk their prey like a cat. They can jump 20 times their body length to pounce on an insect. Sometimes a jumping spider will anchor itself by a strand of silk, and launch itself into space after a flying insect – just like a bungee-jumper. The spitting spider stuns its prey by shooting it with a nasty glob of venom and silk.

Although most spiders hunt insects, a few spiders, such as tarantulas, are big enough to eat frogs, lizards, and even small birds. A few diving spiders capture tiny fish.

Spiders kill their victims with venom (poison). Then the spider pumps special juices inside, turning its prey to liquid. "They suck up their prey like a milkshake," Darrell says. "Have you ever taken an orange, rolled it around, mashed it up, then stuck a straw in to get the juice? That's how a spider eats."

Many spiders spin webs to snare their meals. Different spider species make many kinds of webs – round "orb" webs, funnel-shaped webs, sheet webs, and even underwater webs. The teeny-tiny green spider that Ubick collected spins a small, flat web on an oak leaf.

Silk that's stronger than steel

All spiders spin silk, though not all spiders make webs. Spiders that don't make webs use their silk to line their nests and cover their egg sacs.

Spiders spin silk from special "spinnerets" on their tail end. A spider has many different "faucets" on each spinneret, to spin different kinds of silk. Have you ever wondered how a spider keeps from being stuck in its own web? A spider can spin both sticky and nonsticky silk. When it walks on its own web, it walks on the nonsticky strands. Even if a spider becomes stuck, it can eat its own silk. After a spider climbs up a line of silk, it may pull it up and snack on it!