Session 2: Animals and Food

Key Idea

How does a baby jaguar grow into a large adult? It happens through eating. When an animal eats, its body breaks the food down into small food molecules.

The body acts like a construction crew. It takes these food molecules and rearranges them to build new body structures—like bone, muscle, and skin. Essentially, an animal’s body is made out of the food it has eaten. Without food matter, an animal cannot add mass to its body to grow.

Key Idea

Animals need food for more than just building their bodies; they also need it to move. Food serves as a source of power. Inside the body, some food molecules are broken down to release energy.

This energy powers everything the animal does. It allows a jaguar to run and hunt, and a sloth to climb (slowly!). It also powers invisible internal work, like a beating heart, breathing lungs, and keeping the body warm. Without energy from food, these essential life processes would stop.

Key Idea

If we trace the molecules in an animal's food backwards, we solve a mystery. A jaguar eats a deer, so it gets matter from the deer. But the deer got its matter by eating leaves and grass.

This pattern is true for all animals. Carnivores (meat-eaters) eat animals that ate plants. Herbivores (plant-eaters) eat plants directly. Therefore, the matter and energy in almost every animal’s diet originally came from plants. Plants are the source of the ecosystem's food supply.