This is a more or less random process whereby non-coenobic colonies or filaments break into two to
several fragments having the capacity of developing into new individuals.
Under unfavorable conditions, particularly of desiccation, many algal groups produce thick-walled
resting cells, such as hypnospores, hypnozygotes, statospores, and akinetes.
Hypnospores and hypnozygotes, which have thickened walls, are produced ex novo by protoplasts
that previously separated from the walls of the parental cells. Hypnospores are present in Ulotrix
spp. (Chlorophyceae) and Chlorococcum spp. (Chlorophyceae), whereas hypnozygotes
are present in Spyrogyra
spp. (Chlorophyceae) and Dinophyta. Hypnospores and hypnozygotes
enable these green algae to survive temporary drying out of small water bodies and also allow
aerial transport from one water body to another for instance via birds. It is likely that dinophyceae
cysts have a similar function.