Spiders are found worldwide on every continent but Antarctica, and inhabit nearly every ecosystem except air and sea. Unlike most arthropods, spiders have no extensor muscles, and instead move their legs by hydraulic pressure. As of 2008, at least 43,678 species of spiders have been recorded by taxonomists. While the venom of a few species 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 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 of various combinations of patience, cruelty and creative powers. Matt wanted a spider that looked like it was made of fragmented glass, and this is what we came up with. Spiders make really cool tattoos, I would love to do more!