The narrator describes the physical features of the striped skunk and how they help her root through the trash. The skunk then sees her prey, a mouse. Despite having poor eyesight, the skunk is able to follow the mouse using other senses.

The narrator describes how the physical features of the brown rat allow her to swim effortlessly in her environment. She uses her small size to travel through a tunnel, a path which is less prone to predators. On the way home, the rat uses her abilities to hold her breath underwater as well as to remove water from her fur to avoid hypothermia.

The narrator describes how the physical features of the kangaroo rat allow it to survive for a short amount of time in the intense dryness and heat in Arizona. Afterwards, the kangaroo rat seeks shelter underground to protect itself from the harsh environmental conditions.

The kangaroo rat encounters a scorpion and has no means to escape. Suddenly, a scorpion mouse, which preys on scorpions, arrives and fights with the scorpion. The narrator explains how the scorpion mouse is advantaged by its evolved biological resistance to the scorpion's venom. Eventually, the scorpion retreats.

In an apartment building, the golden hamster leaves its cage to search for food and bedding. The hamster is shown to be well-suited to its surroundings in the sense that it effectively transports household items in its mouth as well as enjoys human affection.