Diatoms reproduce by two different modes, sexual and asexual.

Sexual reproduction:

The ability to reproduce sexually is closely associated with cell size of the diatom. It is the most prevalent method of restoring cell size, and it is often triggered when the size of a cell is less than a critical level (usually smaller than half of the original size for most species). The process of sexual reproduction is different for centric and pennate diatoms.

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