Cyclomorphosis

Cyclomorphosis (also known as seasonal polyphenism) is the name given to the occurrence of cyclic or seasonal changes in the phenotype of an organism through successive generations.

It occurs in small aquatic invertebrates that reproduce by parthenogenesis and give rise to several generations annually. It occurs especially in marine planktonic animals, and is thought to be caused by the epigenetic effect of environmental cues on the organism, thereby altering the course of their development.