The zebra spider, Salticus scenicus, is more common and fascinating than many people realize.  Check your window screens and outside walls — I often find they are conspicuous in the first warm days in early spring, but you can find them throughout the warm months.  Like all jumping spiders (family Salticidae), they are fun to watch.  You may find one feeding on an insect that is much larger than the spider.

Many liberties were taken with the caricatures in this drawing, of course, but I think it captures the outsize personality that these spiders project.  They are actually even smaller than shown — only a few millimeters.  But they are among the most interesting creatures easily observed around the home.

In explaining how spiders jump, I put “blood” in quotes because, like arthropods in general, they have an open circulatory system.  This is a system where, like ours, a fluid is pumped by the heart and travels through blood vessels; but unlike ours, it then leaves the open end of the blood vessels to circulate throughout the tissues of the body, where it is analogous to the interstitial fluid (and subsequently lymph) in humans.  Therefore in spiders, the term hemolymph is used to describe the circulating fluid.

You can learn more about the life of zebra spiders at Animal Diversity Web, and Bug Guide is a good general source for identifying this and other spiders. An excellent “jumping-off” point for those intrigued by jumping spiders in general is Salticidae.org, where you will find links to blog posts about jumping spider-collecting expeditions (with beautiful photos), and to information about laboratory research on acoustic communication among these otherwise highly visual spiders.