The tarantula's appearance is every bit as fearsome as its reputation. They tend to be large, hairy and aggressive, with jaws that are positioned to open and shut vertically when viewed from the front, as if the spider's head had been twisted 90 degrees.

In North America, about 30 species fit this description, most of which live in underground burrows lined with silk webbing. Surprisingly, the tarantula's venom in most instances is not nearly as potent or harmful to humans as that of the black widow or brown recluse. While bites to humans may hurt a great deal and cause some deadening (or necrosis) of the tissue immediately surrounding the wound, most simply don't produce serious injury in either the short- or long-term. In any case, the biggest and deadliest tarantulas tend to live in tropical regions such as the Amazon Basin.