This short film sponsored by the National Film Board of Canada was nominated for the Oscar for Best Animated Short. Artistically, you can see that the 1970s were the nadir of animation, as the quality of the artwork is pretty poor by standards of the medium's heyday of the 1940s and 50s as well as compared to animation today. So the film will not wow you when it comes to the backgrounds or animations.
The purpose of the film is to illustrate the process of evolution and natural selection, though it does NOT do it through dull narration or even much in the way of teaching. Instead, it uses a quirky sense of humor to show some bizarre creatures changing, making babies or getting eaten--but mostly getting eaten. And because it isn't overtly educational but comical, it is pretty watchable.
Compared to other shorts of the same era, I'd give this one an 8. Compared to shorts today, I'd give it a 3, as the animation standards today are MUCH higher than the 70s. Overall, I'd say a decent IMDb score is 6. Times have definitely changed.