1 Â At about 5 million trillion trillion strong, bacteria and their cousins, the archaea, vastly outnumber all other life-forms on earth.
2  Lined up end to end, they would stretch some 10 billion light-years—literally from here to the edge of the visible universe.
3 Â And there are always more on the way. Pseudomonas natriegens, an ocean-dwelling bacterium, can go from birth to reproduction in 10 minutes flat [pdf]. In five hours a single cell could theoretically give rise to more than 1 billion offspring.
4 Â Bacteria have been around for at least 3.5 billion years, making them the oldest known life-form on the planet.
5  Humans didn’t catch a glimpse of them, though, until 1674, when Dutch scientist Antonie van Leeuwenhoek spotted tiny swimming “animacules” while fiddling with the newly invented microscope.
6 Â A compelling argument for brushing: He discovered them while examining pond water and scrapings from the human mouth.
7 Â Most bacteria have yet to be identified. In 2003 geneticist J. Craig Venter began trolling the high seas and analyzing the water. On his first trip he fished out more than a million never-before-seen bacterial genes.
8 Â The first artificial life-form will be not a robot but a bacterium. Not content with finding natural bacteria, Venter is leading an effort to build a bacterium from scratch.
9 Â No escaping them: Your body has 10 times more bacterial cells than human cells.
10  Can’t catch them, either. Whipping their tails, E. coli can travel 25 times their own length in 1 second, equivalent to a horse running 135 miles per hour.
