The characters are featured in a nature documentary show called "Mutual of Omicron's Wild Universe," divided into three segments.
Before Zapp can fertilize Leela's eggs, he is caught and eaten by Brrr, a grizzly bear version of Lrrr.
Professor Farnsworth, as a rare Pinta Island tortoise named Lonesome Hubert, is persuaded by his animal friends to find a mate so his species can continue.
Once Hubert arrives, he mistakenly begins to mate with a large, tortoise-shaped boulder until the real tortoise (resembling Mom) shows up and angrily knocks it down a hill.
Several months later, these hatch into tortoise versions of Walt, Larry and Igner and promptly fall down the hill, where the boulder rolls over and crushes them, leading to the species' extinction.