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categories: What are bacteria > Bacteria and our senses
Bacteria are too small to see with the naked eye. With the development of the microscope, which is nothing but a set of strong optical lenses, Antony van Leeuwenhoek (Source: Museum of Paleontology, Berkeley) made it possible for the first time to "see the unseen". Photo gallery of bacterial pathogens (Source: N. Chamberlain). If you can't get enough of this, check out our special feature file: Images of bacteria.
Who said bacteria couldn't be seen with the naked eye? There only need to be enough of them. The water in a vase of flowers becomes cloudy when it is not daily refreshed...there you can see your bacteria! And minute as they are, there are a lot of them. Look at the video to see bacteria divide (Source: J.A. Sullivan). Note that they grow in a circular way. When millions of bacteria are derived from one single cell, the result will be a small round heap, which we call a colony. To a bacteriologist, the shape of bacterial colonies is very informative (Source: Science buddies). To an artist, colonies are just beautiful (with a bit of computation) (Source: Genome News Network). Each sort, or species, forms a particular shape and color (yes, bacteria can have colors too), and this was an early way of recognizing and describing bacterial species. The study of bacteria (see our exhibit on bacteriology) still uses microscopy as a major tool of identification, with the use of diverse staining methods.
Taste them
Can we taste bacteria? Maybe not, but we can taste their metabolic products. When milk has gone sour, it is because bacteria are growing in it. These are lactobacilli. And even the stale taste in your mouth when you wake up in the morning is mainly due to bacterial activity.
Smell them
Bacteria have a smell of their own, or, more correctly, their metabolic products have. A bacteriologist will smell the plate on which his bacteria grew to check, just as he looks at the colonies to inspect their form. And don't you check the smell of milk to make sure it has not gone sour? The smell of pond water of questionable quality which smells like rotten eggs is also produced by bacteria.
Feel them
Can you feel bacteria? Difficult, but when they are infecting your body, the pain can be quite noticeable! However, it is often your bodies defense that causes the pain. For instance, during an ear infection, fluid is accumulating in the middle ear, and this causes pressure on the sensitive drum. So it may not be the bacteria themselves you are aware of, but the pain is nothing less serious!
But can we hear them?
The content of this page is copyright of the Virtual Museum of Bacteria and was written by Dr. T. M. Wassenaar (curator), with support of the Foundation for Bacteriology.
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Page last modified: 08 Mar 2007
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