Spiders are air-breathing arthropods that have eight legs, and
fangs that can inject venom. They rank seventh in total species
diversity among all other groups of organisms. Spiders are found
all over the world on every continent except for Antarctica, and
have become established in nearly every habitat, excluding air
and sea colonization. There are approximately 40,000 spider
species that exist throughout the world. While the venom of a
few types of spiders is dangerous to humans, scientists are now
researching the use of spider venom in medicine and as non-
polluting pesticides. Spider silk provides a combination of
lightness, strength and elasticity that is superior to that of
synthetic materials, and spider silk genes have even been
inserted into mammals and plants to see if these can be used as
silk factories. As a result of their wide range of behaviors,
spiders have become common symbols in art and mythology
symbolizing various combinations of patience, cruelty and
creative powers. Female spiders can la