Different types of bacteria use various mechanisms to navigate their environments. These methods of movement include using appendages, such as flagella and pilli, using chemical propulsion and joining other bacteria as part of a biofilm.
A flagellum is a whip-like tail used by some bacteria. Its propeller-like motion allows the bacterium to swim forward. Pilli are hair-like appendages that cover the surface of a bacterium. The pilli grip surfaces and aid bacteria in moving across them.
Bacteria that use chemicals to move do so in two ways: excreting slime and using chemotaxis. Bacterial slime aids the bacterium in oozing forward, whereas chemotaxis uses chemical cues in the environment to passively move forward. When bacteria use chemotaxis, they are drawn towards the particular chemical they need. When the chemical signal is no longer present, the bacteria stop moving.
Biofilms are large clusters of bacteria that produce a thin film. The bacteria that make up a biofilm move together in a defined pattern, retaining the integrity of the film. Some biofilms remain stationary, sticking to objects rather than moving as a group. Biofilms are also implicated in bacterial human diseases, such as dental plaque and gum disease, urinary tract infections and cardiac infections.