Spirochaetes are motile bacteria. They have very fine flagella attached to the cell surface, and the rotating action of these propel spirochaetes through the medium. Spirochaetes have a spiral body and twist through the medium. These are from the termite Incisitermes. Many flagellates that are endobiotic in termites have bacteria attached to the outside. In many cases these are spirochaetes. They move actively and this can produce the propulsive force for the the eukaryote flagellate. Phase contrast.