The reproduction of the genus "Drymonema" is similar to the reproduction of all Scyphozoans. Scyphozoans and "Drymonema" species alternate between sexual and asexual reproduction stages. The miniature-adult types include many open-ocean scyphozoans. Many sources refer to only scyphozoans as "true jellyfish". Scyphozoans generally have planula larvae that develop into sessile polyps. Scyphozoans have existed from the earliest Cambrian to the present.