In the coastal waters of Southern California, lives a small fish with an unusual spawning pattern - it breeds on land in a pattern which follows the phases of the moon. Shows the spawning process of the grunion, the fish that spawns on land. Uses animated drawings to explain that the spawning is related to the moon and the tides. Follows the day-by-day development of the grunion egg as seen through a powerful microscope; uses microphotography to portray the actual heart beats, the circulation of the blood, and the movements of the embryo.