A Short report of Spiders

Essay by nsbhsJunior High, 7th gradeA, September 2006

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Crawling around on eight legs, are some of the most fascinating invertebrates on earth, spiders. There are approximately 40000 known species of spiders. Of the 40000 species, only a few are dangerous to humans. Spiders belong to the Arachnid class, which contains scorpions, ticks, mites.

These creepy creatures live on every continent except Antarctica. They could live around anywhere, even in water, where food lies nearby. They differ from insects in several ways. They crawl on 8 legs rather than 6, they have 2 body segments, the cephalothorax and the abdomen, rather than three body segments and they don't have compact eyes like those of an insect.

A spider's life cycle contains four stages: egg, larva, nymph and adult. Most spiders live up to 1 to 2 years, with the exception of female tarantulas, which can live up to 20 years. Male tarantulas only live up to 2 to 3 years as many male spiders soon die after mating.

They are known for their web spinning abilities. Many spiders use their webs to ensnare victims in their delicate but deadly web. When they catch their prey, they inject powerful poison to paralyse or kill them. Once paralysed, the spider vomits juices that contains digestive enzymes into the wound of their prey so their victim's tissues break down and liquefies. The spider then sucks the liquefied insect into its mouth. Sometimes, they store their food for later by wrapping them in silk. Their web not only helps them catch or store food, but provides shelter for their eggs.

Why do some people suffer arachnophobia? It is perhaps due to their appearance. Spider bites are rare and are helpful to our world. Of the 40,000 species, only 30 contain poisons that are harmful to humans. Humans are more likely to...