a subclass of chordate animals of the class Thaliacea of the subphylum Tunicata. The animals live as plankton in the tropical seas. The barrel-shaped body is up to 3 cm long. Cyclomyaria have a complex life cycle. From the egg develops an embryo with a tail and a notochord; then it is transformed into a foster form (an individual of the first asexual generation). On a ventral outgrowth (stolon), the foster form propagates by gemmation, and these gemmae migrate to the dorsal stolon. Here some of the gemmae turn into feeding individuals, or gastrozooids, providing food for the whole colony, while others turn into phorozooids, to which the sexual praegemmae attach. The gastrozooids and phorozooids are not able to reproduce; the sexual praegemmae (the second asexual generation) propagate sexual individuals, or gonozooids, by gemmation. The grown phorozooids break away from the foster form; from them individual gonozooids later form, break off, and begin to swim independently.
A. V. IVANOV