Mature eggs are presumably spawned and fertilized in the sea by sperm produced and released by male medusae , as is the case for most hydromedusae .
The related species Turritopsis rubra seems to retain fertilized eggs until the planula stage .
Mature eggs are presumably spawned and fertilized in the sea by sperm produced and released by male medusae , as is the case for most hydromedusae , although the related species Turritopsis rubra seems to retain fertilized eggs until the planula stage .