In biological terms the various forms are examples of evolutionary strategies and are largely analogous rather than homologous; the gonozooid phases of tunicates and bryozoans, for instance, did not originate from a common ancestor.
[5] Polyps from the cnidarian Hydractinia symbiolongicarpus form colonies where labour is divided between reproduction (gonozooids), feeding (gastrozooids) and defense (dactylozooid).
As the whole colony is genetically identical, it is not necessary for each polyp to individually reproduce, allowing more energy and resources to be used for other tasks such as feeding and defense.
[6] Higher gonozooid frequencies lead to more sexual reproduction and thus more offspring being genetically different from their parents.
The resulting higher genetic variance increases the chances of beneficial phenotypes appearing in the population.