One of the first things to realize about the microbial world is that microorganisms are everywhere. Some microorganisms can live quite happily in boiling hot springs, whereas others form complex microbial communities in frozen sea ice. Most microorganisms are harmless to humans. You swallow millions of microbes every day with no ill effects. In fact, we are dependent on microbes to help us digest our food and to protect our bodies from pathogens.
Microbes are the dominant form of life on planet Earth.
The Microbe Zoo was co-developed by a former student in this class. One take home message is that microbes are as much smaller than an elephant as an elephant is smaller than the planet Earth. Therefore an elephant represents a planet's worth of habitable niches for microorganisms. In fact, there are probably more microbes on and in an elephant than there are animals on the earth.