Webless Spiders: How They Trap Their Prey Without Webs
Close-Up: A Spider's Eight Eyes
There are over 30,000 kinds of spiders in the world today. Don't let these creepy-crawly things fool you: they are not part of the insect family. Their habits and body structures are different than insects. For one thing, spiders have eight legs, eight eyes, fangs, and no antennas or wings, whereas most insects have six legs, two eyes, and no fangs, and some have antennas and wings.
Also spiders are all carnivores, which is not true of all insects. The first thing that most people think of when they think of spiders is "ewww." The second thing is spider webs, which is how many spiders trap their prey. Surprisingly, the majority of spiders do not actually build webs. They use means like hiding behind "trapdoors," jumping on their prey, ambushing them, and even spitting a glue-like substance to immobilize their victims.
There are roughly 5,000 different species of jumping spiders, making it the largest subgroup of spiders. They are known for their extremely keen vision, which they need when traveling and attacking prey. They travel by jumping from place to place using a silk tether that assures that they won't lose their place even if they happen to fall. If they fall, they will just climb up the silk thread and get back to where they once were.
They have a unique jumping mechanism. Rather than relying on a great muscular system, like cats, kangaroos, and other mammals, they rely on the circulatory system, which works like a hydraulic piston. This lightweight mechanism allows them to jump unusually high, despite their short legs.
When it comes to hunting, they rely on both their jumping skills and their great eyesight. They will pounce on their victim from ten to twenty millimeters away, leaving it completely immobile. A strike occurs so quickly, in about 1/700th of a second, that the spider's prey won't be aware that anything has approached. Although all spiders are carnivorous, a few in the jumping spider family also eat pollen and nectar, but even these for the most part eat meat. Unlike other spiders, these usually have only six eyes instead of the traditional eight.
Although jumping spiders are known for their speed, some rely on their ability to spit. A spitting spider or scytodid usually has a big head that contains enlarged venom glands. Their head measures a little less than a quarter of the total size of the spider.
Their spit consists of a gummy substance that is venomous. When spraying their victim, they often will move in a zigzag fashion, which will cause the venom to cover the entire surface of their prey. Because the substance is very sticky, it will then immobilize their prey, giving the hunter time to approach and eat their victim. This gummy substance is so effective that it actually allows the spider to capture prey larger than itself.
While many spiders use webs as traps, some spiders use trapdoors. They will burrow into the ground and set up a trapdoor right outside their hideout. They make this trapdoor out of soil, vegetation, and silk, similar to the silk used in a spiderweb.
Not all trapdoor spiders burrow in the ground; some will construct a tube of silk with a trapdoor in a bark crevice. Regardless, the trapdoors are camouflaged very well and are very hard to see. The hinge is usually made of spider silk. As a trapdoor spider awaits its prey, it will use its claws to hold the door shut. Once it feels the vibrations of an insect, it will release the trapdoor, jump out, and capture its prey.
Trapdoor spiders are usually large, hairy, and harmless to humans. They also use their trapdoor to hatch their young. The baby spiders will live in the burrow for two or three weeks before they leave to live on their own, where they will burrow and make trapdoors of their own.
One of the most feared spiders is the tarantula. Tarantulas are known for their size and hairiness. Although there are so many subspecies and the sizes range greatly, most tarantulas' bodies fall within 1 to 4 inches (2.5 to 10 centimeters), not including their legs. The males are generally smaller. There are nearly 900 species of tarantulas.
These spiders use the ambush method to capture their prey and do not build webs. Most tarantulas will stick to insects as their main source of food, but bigger tarantulas, like the Goliath Bird-Eating Spider, will kill and eat mice, birds, and even lizards.
Despite their bad rap, tarantulas are not as harmful as they may appear. Although many fear the tarantula's venom, generally their venom is not strong enough to kill a person, though it may cause extreme pain. A very few people suffer an allergic reaction. Tarantulas generally will not bite unless cornered; they prefer to run rather than bite.
Despite what people might assume, the majority of spiders do not actually make webs, although all spiders share some characteristics (they have eight legs, are not insects, and are carnivorous) and most produce a silk-like material of some kind to help them trap their prey.
© 2010 Angela Michelle
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