Behaviour of Micro-organisms

Organisms are constantly being bombarded by stimuli in their envi­ ronment (and also by internal stimuli), and a common way of responding is by movement. This is an aspect of irritability, or excitability, or behaviour. Response to stimuli by movement is found in all organisms: it represents one of the universalities of biology. Yet at the molecular level it is one of the least understood of biological phenomena. Micro-organisms are no exception. If motile, they respond to stimuli by active move