Diatoms reproduce by binary fission, two new organisms are formed within
the parent cell wall. The two new cells receive a parent cell theca as
epitheca, and a new hypotheca is formed for each new cell. As a result
of reproduction the new cells experience a size reduction. The extent of
the reduction in size is dependant on the species of diatom, but some parent
cells can be as much as 8 to 10 times larger than the daughter cells. The
size of the new cell increases by auxospore formation, where the cell sheds
its theca, and a large sphere surrounded by organic material is formed.
Inside the sphere a new frustrule is formed, and the cycle is continued.