However, before the onset of a dry period a switch to producing mictic eggs is frequently observed, as these eggs will ensure the survival of the population until the next favourable period. The development of the embryo is by spiral cleavage. Free-swimming rotifers commonly produce miniature replicas of themselves, whilst sessile forms tend to have dispersive larval stages. Most rotiferan classes are defined by their oral arrangement and coronal adaptations. This class is represented by a single genus of rotifers, which exist as commensal organisms of marine crustaceans.
Eggs are haploid, and require fertilisation in order to develop into male or female adults.
This speciose class of rotifers is characterised by the presence of two trochal discs. They are active components of the freshwater zoofauna, and move by swimming or crawling. The body is capable of a considerable degree of extension and retraction. Males are unknown, all reproduction occurring by parthenogenesis. As the name suggests, this class of organisms is characterised by the presence of a single ovary, and the production of both mictic and amictic eggs.