Examines the sea horse, the only fish that swims upright. We watch it use its prehensile tail to wrap around plants and other sea horses. A frontal bulge houses organs including an air ballast. Three fins propel this fish. We see a female place her eggs in a male's pouch where they are fertilized and nurtured until birth in violent contractions. Inside the pouch are nurturing blood vessels. We then follow the growth of an embryo, greatly magnified: we examine its heart beating and its dorsal fin moving. Young sea horses attach themselves to each other. The film ends with images of many sea horses moving on the ocean floor, superimposed on a horse race.