by Janet Spencer
ARACHNIDS
• Spiders are not insects. They are arachnids. What’s the difference? All insects have six legs, whereas spiders have eight. Most insects have wings and antennae, but spiders do not. Insect bodies are divided into head, thorax, and abdomen, but spiders have only head and thorax. Spiders, insects, and crustaceans are all members of the Arthropod phylum, which includes all creatures that have segmented bodies and pairs of jointed legs. Spiders are members of the arachnid class, which also includes ticks, mites, and scorpions. There are over 45,000 kinds of spider in the world.
• Nearly all types of spider have some kind of venom, but there are only 30 known species that have been responsible for killing a human.
• Black-widow venom is 15 times more powerful than rattlesnake venom, but black widows carry only a tiny dose of it, so it’s rarely fatal.
• In World War II so many soldiers were bitten by black widow spiders, who like to live in latrines, that the antidote became a standard part of their medical kits.
• Some spiders use their venom not to bite their prey, but to inject their silk with the poison, which they then shoot at the prey.
SPIDER TACTICS
• About half of the species of spiders build webs. Others use different hunting methods:
• One type of spider digs a burrow in the ground and then surrounds the hole with trip wires which radiate outward like spokes of a wheel. Each trip wire ends at the burrow, where the spider sits with his legs on the strands, waiting for vibrations that indicate a bug is in the vicinity. It then rushes out and grabs the bug.
• One type of spider simply sits on a flower and waits for a bug to come in search of nectar. The spider is able to change color from white to yellow to pink to match the shade of the flower it’s sitting on.
• The wolf spider can change its color from brown to gray depending upon what type of vegetation it’s sitting on.
• One type of spider is accurately named the warty bird-dropping spider because it is perfectly camouflaged as bird dung. It also gives off a realistic odor which repels predators but attracts flies.
• Ant spiders that live in the rain forest not only look just like ants but act like them too. Most predatory insects know that ants taste bad, they bite, and they attack in large numbers. So ant spiders run in a zigzag patterns just like ants do; they wave their front legs around in the air as if they were antennae; and they hang out where ants live.
• Another type of spider found in Uganda looks just like a wasp, and an Australian species of spider looks like a scorpion and even raises its abdomen over its head when threatened. One harmless type of spider looks exactly like the deadly black widow, except that it lacks the red hourglass on the abdomen.
• Most spiders kill their prey by biting it, injecting venom. But the hackle orb spider has no fangs and no venom. Instead, it wraps its prey in layer after layer of spider silk, binding it so tightly that the insect is crushed.
SPIDER TACTICS
• One type of spider found in Taiwan builds a life-size model of itself in order to act as a decoy. Using pellets made from the remains of insects, old leaves, empty egg sacks, and silk, this spider constructs a replica of itself. When predatory wasps attack, the spider is safely hidden away while the wasp attacks the decoy.
• The common zebra-striped jumping spider that’s found in North American backyards can jump up to seven inches (18 cm). It hangs out in high places and waits for an insect to fly past, whereupon the spider launches itself into space, hopefully landing on the back of its airborne prey on the way down. If it should miss, it pays out a dragline, floats to the ground, then climbs back up to a high spot again.
• A bolas is a rope with a ball attached at either end. When a cowboy throws a bolas at a running cow, the bolas wraps itself around the cow’s legs and trips the animal so it can be caught. The bolas spider forms a similar weapon from its silk. Hanging from the underside of a leaf, the pea-sized spider will dangle a line of silk with a sticky ball at the end. In the early evening hours of dusk, it’s hunting for cutworm moths, which are active at sunset. The spider gives off the scent of a female cutworm moth that is ready to mate, hoping to attract a male cutworm moth. If a moth flies by, the spider swings the bolas at it, hoping to ensnare it. If the hunt is unsuccessful, the spider reels in the bolas and eats it, absorbing its protein. Later in the evening, it lets the bolas dangle once again, but this time the spider gives off the scent of a moth called smoky tetanolita which is active around midnight. Now the spider emits the mating scent of that species of moth, hoping for better luck.
WEAVER WOMAN
• According to myth, a Greek peasant had a daughter who grew up to be a talented weaver. She was so skilled that she became boastful and claimed to be a better weaver than Athena, the Greek goddess of craftsmanship. Athena disguised herself as an old woman and warned the girl against angering the gods, but the girl scoffed, and demanded a weaving contest with Athena so she could prove her skill. At this, Athena dropped her disguise and the contest was on.
• Athena wove a tapestry that depicted all the gods in all their glory, but the peasant girl produced a tapestry that depicted all of the gods in their behind-the-scenes trysts and deceits. Athena saw that the work was superior, but was so angered by the choice of subject matter that she destroyed the tapestry and the loom. The peasant girl was so shamed that she ran off and hanged herself.
• Chagrined, Athena cut the girl down and brought her back to life transformed as a spider, and the rope she hanged herself with was turned into the spider’s silk. Ever since then, the peasant girl’s descendants have been wandering the world, weaving with skill.
• Today the taxonomical word for the class of arthropods that includes spiders, scorpions, mites, and ticks springs from the peasant girl’s name: Arachne, which gives us Arachnid.
IT’S A FACT
• The bird-eating spider of the Amazon has a leg spread of 10 inches (25 cm). It usually preys on bugs and hummingbirds, but will attack anything. It doesn’t build webs, but stalks prey, seizing it and injecting paralyzing poison. It can live two years between meals and has a lifespan of 20 to 30 years. The poison is not fatal to humans, but it can make a person ill. When a naturalist first described a spider that ate birds in the year 1705, scientists of the day refused to believe her.
