One night, deep in the ocean, Charlie the whale was getting ready for bed, but there was something that she couldn't quite get off her mind.

"Momma, why do we have to breathe air at the surface of the water but my friend Pat doesn’t? It’s just not fair!" exclaimed Charlie. "Well honey," Mama Whale replied, "that's because Pat is a pufferfish and we are whales! We evolved differently."

"Evolved?" asked Charlie. "What does that mean?"

“To evolve means to slowly change, which we’ve been doing for hundreds of thousands of years in a process called evolution!” Mama Whale answered. Charlie's curiosity was still not sufficed. "But why do we need to change? What's evolution?" she pondered.

Mama Whale smiled. "I'm so happy you asked! It's important to know where you came from. Finish getting ready for bed and I'll tell you a story."

Evolution is the theory that all living things, like you and me, developed from earlier types. The differences between those types resulted over many years in order to help the species survive. 48 million years ago, whales like us didn’t exist! At first, our ancestors lived on the land. We didn’t have fins, baleen, or tail flutes.

Instead we had four legs and we walked on land. We had sharp teeth and pointy tails. We even had noses with nostrils at the tip. We didn’t evolve to have blowholes until we became aquatic mammals.

"But I don't get it Mama," interrupted Charlie. "Why did our ancestors do all this changing? Why didn't we stay on land?"

Mama Whale laughed. "Patience, little one!"

Evolution results from another process called natural selection. In this process, the species that are the best at surviving in their environment live on to have lots of kids for the next generations. When a species adapts, it means their bodies change to help them survive better. When whales could no longer live on land, over time they lost their legs and developed fins to live underwater.