The Cdv filaments then pull the membrane inward, constricting the cell, as you can see in this Sulfolobus acidocaldarius at a later stage of division. Again, the exact mechanism is unknown.
The majority of bacterial and archaeal cells divide by one of these two mechanisms–FtsZ or Cdv–but not all do. Some species have neither FtsZ nor Cdv, and we are still figuring out how they divide.
