Taxi - movement of bacteria to the food

Friendly user-interface simulating the chemo-taxis movement of biological systems

How do bacteria find their way to the food ? many biological systems use the chemo-taxis algorithm to improve their conditions and hence, their chance to survive. Chemo-taxis in general refers to movement influenced by chemical properties of the medium. In this model, we have a group of independent cells in 2-dimensions. Each cell moves in a straight line in random orientation until it tumbles. When it tumbles, the cell gets a new and random direction for propagation, independent of the past. Tumbles occur in some rate of events per unit time. The cell can regulate its tumbling-rate. Furthermore, the cell can detect and remeber local food concentartion. The chemo-taxis algorithm is as follows: If the cell detects a positive change in food concentartion (the cell is happy) - it lowers the tumbling-rate (less tumbles per second, movement in longer straight lines). If the cell detects a negative change in food concentration (the cell is sad) - it raises the tumbling-rate. If the cell detects no change in food concentration - the tumbling rate returns to some default, normal value of tumbling-rate (this is the adaptation mechanism).
http://www.weizmann.ac.il/mcb/UriAlon/