Entwicklungsbiologie der Ascidie Halocynthia roretzi in der Mutsu-Bucht, Japan: hermaphroditisches Ablaichen, Befruchtung der Eier, Larvenbildung, Ausschlüpfen nach 48 Stunden, Metamorphose zum Jungtier nach 14 Tagen, Erlangen der Geschlechtsreife nach zwei Jahren. Ascidie Halocynthia roretzi ist zwischen Vertebraten und Evertebraten anzusiedeln.

Shows the life cycle of the sea squirt Halocynthia roretzi. Halocynthia adults from Mutzu Bay in Northern Japan are shown to spawn at a certain time of the day and differences in spawning time have been used to define three sub-species. Shows in great detail the fertilization and development of an egg through to the larval form. Metamorphosis follows and development is shown up to maturity and the adult form. The importance of this group for developmental biologists is in the larval stage where the animal develops a notochord and a swimming tail. In Japan Halocynthia is farmed for food, and sequences in the film show fishermen harvesting the adult animals.