Waves in bacterial colonies
Patterns are also observed in colonies of bacteria. These single-cell organisms often communicate by emitting some chemical, called a chemoattractant. Other bacteria can then move in the direction in which the concentration of this chemoattractant increases the fastest, thereby leading to cell aggregation. This phenomenon is called chemotaxis. In some way, this is a mechanism to make a collection of unicellular organisms behave collectively.
Bioconvection provides another example of wave patterns. We briefly discuss these two aspects of pattern formation in the next two slides.