The medusa stage is very often reduced to an appendix of the polyp stage. The medusa can be reduced to a varying degree as given in the scheme above (schematic longitudinal sections). In the cryptomedusoid, the radial canals are obliterated, in the heteromedusoid the gastrodermal layer is absent, in the styloid, the epidermis is very much reduced. The spadix is homologous to the manubrium of a medusa. Epidermis in red, gastrodermis in green, gametes in yellow, v = velum.
Note, the term gonophore (meaning gonad bearer) refers to either a medusa bud or one of these sessile sporosacs. In other words, a gonophore is a medusa, a medusa bud, or its derived homologue.