• The ancient Greek poet Ovid spun the tale of a young woman named Arachne, who boasted that she could weave as well as the goddess Athena. After a weaving contest between mortal and goddess, Athena began beating Arachne, who tried to hang herself in fright. Athena turned the arrogant weaver into a spider, and Arachne and her descendants have since then been weavers that hang from threads—or so the story goes.

• "Arachnid" isn't just a highfalutin word for spider. Spiders are arachnids, but not all arachnids are spiders. Arachnids are members of a class of animals that includes spiders, scorpions, mites, and ticks. What they all have in common—and what distinguishes them from insects—are four pairs of legs and