A spirochete is any of many motile, gram-negative bacteria in the order Spirochaetales. They are characterized by having a flexible spiral shape; these bacteria are some of the easiest to recognize. They move with a twisting motion with the aid of their axial filaments, which are specialized internal flagella (a spirochete may have up to 200 of these filaments). Their cells can be from 5 to 500 micrometers long, which is gigantic in the germ world.
Most spirochetes are found in liquid environments such as mud, water, and body fluids. They reproduce via binary fission and are heterotrophic (they eat other matter or organisms); most species are either decomposers (saprophytes) or pathogens (parasites).
Many spirochete species cause human diseases:
There are many, many spirochetes which cause disease in animals; spirochetal infections can cause diarrhea and systemic infections in a wide range of domestic animals. Some of these illnesses can be very damaging to livestock and some can be transmitted to humans.
Some spirochetes will change their surface proteins to foil a person's or animal's immune system; thus, spirochetal diseases are very hard for one's body to fight off without the aid of antibiotics such as penicillin and clindamycin. | 
