Penguins have special colors on their bodies that help them hide from other animals in the ocean. Their white bellies match the bright sky when a fish looks up at them from under the water. At the same time, their black backs blend in with the dark water when a bird or animal looks down at them from above. This clever coloring helps penguins stay safe and catch food more easily.
Another way to say this is: Penguins wear a kind of natural costume with a white tummy and a black back. This costume helps them disappear in the ocean, depending on where you are looking from, so they don’t get caught by fish or other animals.