An interphase vegetative cell may be in either the flagellate or the aflagellate state, depending on the species (some are more likely to be found as flagellate cells, others as aflagellate cells) and the prevailing environmental conditions. A cell in one state may transform into the other state, at any time, by discarding or regenerating its flagella. Vegetative cells divide by binary fission. Flagellate cells become aflagellate, by flagellar loss, and settle prior to division. Either or both progeny may regenerate flagella and swim away or remain in the aflagellate state. Cysts apparently form from single vegatative cells. Four cells are released at excystment. The triggers for cyst formation and release are not well known. There is no evidence for sexual reproduction.

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