The Amazing Journey of Whales:
From Land to Sea
Preview the Questions
What kind of animals did whales come from?
What is Pakicetus, and how did it live?
How did Ambulocetus move around?
Name three changes that helped early whales live in water.
Why did whales’ noses move to the top of their heads?
How are whales and hippos related?
What is evolution?
How do scientists learn about ancient whales?
What does a fossil of Basilosaurus show us?
Why is studying whale evolution important?
Long Ago, Whales Walked on Land
Did you know that whales didn’t always live in the ocean?
Millions of years ago, the ancestors of whales walked on land! They had four legs, fur, and even hooves like deer or pigs. These ancient animals lived near rivers and lakes.
Over time, some of them began spending more time in the water. Slowly, their bodies changed to help them swim better. This amazing journey from land to sea took millions of years and shows how animals can change to survive in new places.
Meet the Ancient Whales
One of the first whale ancestors scientists know about is called Pakicetus. It lived around 50 million years ago. It looked a bit like a wolf but had features that helped it swim. For example, it had long legs for walking but also a long tail and a body shape that made it easier to move in water.
A few million years later, another animal appeared called Ambulocetus. Its name means “walking whale.” This creature was about the size of a sea lion and could both walk and swim. Its legs were strong for walking, but its feet were shaped like paddles. It probably swam by wiggling its back legs, just like otters do.
As time passed, whale ancestors began to look more and more like modern whales. Their front legs turned into flippers, their back legs got smaller, and they grew stronger tails to help them swim. These tails had wide, flat parts called flukes that helped push them through the water. Their nostrils moved from the front of their faces to the top of their heads, becoming blowholes.
Changes on the Inside, Too
The changes weren’t just on the outside. Whale bodies changed on the inside as well. Their lungs became stronger so they could hold their breath longer. Their ears adapted to hear better underwater. Their kidneys began to work better in saltwater, which helped them stay healthy in the ocean. These changes took millions of years, but slowly the animals that once walked on land became the full-time swimmers we know today.
What Do Whales and Hippos Have in Common?
It may be hard to believe, but whales are closely related to hippos. Scientists discovered this by studying their bones and DNA. Both whales and hippos belong to a group of animals called artiodactyls. These are animals with even-toed hooves, like pigs, deer, and camels.
The common ancestor of whales and hippos lived more than 50 million years ago. This animal probably lived both on land and in water. Over time, some of its descendants stayed on land and became animals like deer and pigs, while others moved into the water and slowly evolved into whales.
Whale Evolution Takes Time
The process of whale evolution didn’t happen overnight. In fact, it took around 10 million years for ancient land animals to become fully ocean-dwelling whales. That may seem like a long time, but in nature, big changes like this always take a while.
Evolution happens when animals with helpful traits survive and have babies who also have those traits. Over many generations, those traits become more common, and the animals change.
For example, an ancient whale that could swim a little better than others might catch more food or escape from danger more easily. That whale would be more likely to survive and have babies, who might also be good swimmers. Over time, this would lead to whales with stronger tails, flippers, and other useful body parts for ocean life.
What Fossils Tell Us
Scientists know all of this because they study fossils—ancient bones and body parts that turned to rock over time. Whale fossils have been found all over the world, from deserts to riverbeds to cliffs. These fossils show the step-by-step changes in whale bodies.
For example, scientists found fossils of a whale called Basilosaurus. It lived about 40 million years ago. It looked very much like a modern whale, but it still had tiny back legs. These legs were no longer useful for walking, but they show that whales came from land animals.
Fossils also show how whales moved from shallow water to deep ocean habitats. As whales became better swimmers, they spread out across the world’s oceans and became one of the most successful ocean animals ever.
Modern Whales and What We’ve Learned
Today, whales live in every ocean. Some are enormous, like blue whales, which are the largest animals to ever live on Earth. Others are much smaller, like dolphins and porpoises, which are also part of the whale family.
By studying the past, scientists learn more about how life changes over time. Whale evolution is a great example of how animals can adapt to new environments. It helps scientists understand how animals might change in the future, too—especially as the world changes due to things like climate change.
Whales are more than just amazing creatures of the sea—they’re also living evidence of Earth’s incredible history.
Vocabulary Words
Ancestor — A living thing from the past that a modern animal came from
Fossil — The remains or traces of an ancient animal or plant
Flippers — Flat body parts used by sea animals to swim
Flukes — The wide parts of a whale’s tail that help it swim
Blowhole — A hole on top of a whale’s head used for breathing
Evolve — To slowly change over time
Adapt — To change to fit a new place or situation
Artiodactyl — A group of hoofed animals, including whales and hippos
Habitat — The natural home of a plant or animal
DNA — The material that carries information about living things
Comprehension questions — please answer with complete sentences
What kind of animals did whales come from?
What is Pakicetus, and how did it live?
How did Ambulocetus move around?
Name three changes that helped early whales live in water.
Why did whales’ noses move to the top of their heads?
How are whales and hippos related?
What is evolution?
How do scientists learn about ancient whales?
What does a fossil of Basilosaurus show us?
Why is studying whale evolution important?