The Fish
The book opens within the world of fish. Red, blue, black, old, star-bellied and even driving a car. A car? Indeed, in this world, a fish can drive a car and it is significant because soon enough the story moves out of the ocean and onto land and the creatures being described are no longer fish. The book is, in a way, a replication of evolution and so the fish are symbols of humanity and the broad diversity of the population.
The Boy and Girl
The boy and girl play witness to a host of examples of the book’s fundamental promise that “funny things are everywhere.” They observe—usually a high perch of one kind or another—a never-ending parade of unusual creatures, sometimes interacting with them, but usually just looking on as a source of enjoyment. In this manner, they become symbols of the essential qualities of life ranking highest in the world of Seuss: wonder and imagination.
Ned
Standing—or, rather, lying—in direct contrast to the boy and girl is Ned. Ned sleeps in a bed that is too small to contain is rather capacious frame. He is first introduced complaining about the bed directly to the read. Two pages later, it is evident that he has called a friend simply to complain more about the bed as well as having to share it with animals that come to visit. Ned symbolizes deadening lack of joy which puts a stranglehold on the imagination and reduces the ability to find wonder in the world.
The One Not Liked So Well
Most of the denizens of the Seussian universe populating this book are fully embraced by the boy and girl. Their sense of wonder allows easy acceptance of some while others just come and go without commentary of a personal opinion. One, however, actually instills an active distaste to the point where the narrator confesses a version to “have this one about.” The one cause of this negative response is perfectly understandable: all he ever does it yell. The symbolism here is highly suggestive. While Ned may be a Captain Bringdown, his opinions can be tolerated because he is not abrasive and anti-social. Maintaining social cohesion requires accepting people like Ned, but those who exist merely to disrupt can be effective distanced while still holding the social order in place.
The Nook
The Nook walks around with cookbook dangling in front of his face from a wire attached to a hook on his tall hat. But the Nook cannot cook any of the recipes in the cookbook because the Nook cannot read. The Nook is thus a symbol of literacy—the ability to read—which is the entire purpose of the book.