Abstract:The life-cycle of the scyphozoan Cassiopeia andromeda was described. The tropical jellyfish alternates between a sessile, asexually propagating polyp form and a typically pelagic, sexually reproducing medusa. Major events in the metagenesis are not autonomous, but depend on the presence of and interaction with special physical, chemical or biological factors. The still water and interaction between mature individuals are important for spawning and fertilization. Scyphistoma is produced by metamorphism from oosperm and planulae. Medusa comes into being within a permissive temperature and light by monodisk strobilation. Budding increases the number of scyphistoma when the temperature is above 20 ℃. Four arms have shaped in the course of strobilation. And the young jellyfish can stand upside down in 12~24 h. Zooxanthellae supplies much energy for scyphistoma and medusa besides feed such as Artemia. In our laboratory, scyphistoma has been kept for a long time and medusa may live for over 2 years.
