A gonozooid is any of the reproductive individuals of tunicate, bryozoan, or hydrozoan colonies that produce gametes.[1][2] Gonozooids may play a role in labour division[3] or in alternation of generations.[4] A gonozooid typically has hardly any other function than reproduction, amounting to little more than a motile gonad.
The production of gonozooids amounts to one aspect of certain classes of alternation of generations. 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]