自然界のつりあい－動物の数は何できまるか

This is one of the films produced by Toei, who began producing educational films in 1954, as a teaching material film for schools. It tracks how many percent of the 10,000 eggs of the American White-tailed worm can safely become adults. During the observation process, the raison d'étaté of other natural enemies, as well as the clever mechanisms of natural balance are revealed.