More than 300 scientists from five continents have pitched in to tend this electronic tree, adorning its branches with new entries and sometimes hosting Web pages on their computers. Starting on the "root" page, visitors can follow links for eubacteria, archaea, eukaryotes, or viruses, reaching pages (with background info and images) for families, genera, and individual species. David estimates that the site catalogs fewer than 1% of known species so far. But where expertise does exist, the branches are sprouting luxurious growth. For example, Wayne's pages devoted to jumping spiders (Salticidae)--which sport four big eyes on their faces and four smaller eyes atop their heads--are crammed with detailed descriptions and photos, as well as QuickTime movies of the critters jumping and performing courtship dances.

Future plans include adding links to TreeBASE, a Web repository of primary molecular and morphological data used to build phylogenetic trees. And the project, run on a shoestring budget, is now looking for grant support. Says David: "For the tree to grow, it needs nutrients."