Giants of the Ocean: Whales

Giants Beneath the Waves

Far out in the deep blue sea, something enormous rises slowly to the surface. With a loud whoosh, a tall spout of misty air shoots into the sky. Then a huge, glistening back rolls past — bigger than a bus. This is a whale, one of the largest and most wonderful animals on our planet.

Whales have swum in the oceans for millions of years. They can be gentle, playful and surprisingly clever. Some sing songs that travel for miles through the water.

In this book, we will meet the giants of the ocean, find out how they breathe and dive, learn what they eat, and discover why these amazing animals need our help. Let's dive in.

Not a Fish — a Mammal

It is easy to think a whale is a giant fish, but it is not. A whale is a mammal, just like a dog, an elephant or a human.

Mammals have three special features, and whales have them all. First, they breathe air using lungs, not gills like fish. Second, they are warm-blooded, which means their bodies stay warm even in cold water. Third, mother whales feed their babies on milk.

Because they breathe air, whales must swim up to the surface to take a breath. They breathe through a blowhole on top of their head. When a whale breathes out, it blasts out warm, wet air that looks like a tall spout of mist.

So whales live in the sea, but they are not fish at all — they are ocean mammals.

The Biggest Animal Ever

The blue whale is the largest animal that has ever lived on Earth. It is even bigger than the biggest dinosaurs that ever walked the land!

A grown blue whale can be as long as three school buses parked end to end. Its heart alone is about the size of a small car, and a child could almost crawl through some of its biggest blood vessels. When a blue whale calf is born, it is already bigger than most cars.

What is amazing is that this giant grows so big by eating some of the tiniest creatures in the sea. The blue whale's favourite food is krill, small shrimp-like animals no bigger than your finger. A blue whale can eat several tonnes of krill in a single day.

Two Big Groups of Whales

Whales are split into two main groups, depending on how they eat.

The first group is the baleen whales. Instead of teeth, these whales have rows of bristly plates called baleen hanging from their upper jaw. The whale takes a huge gulp of seawater full of krill and small fish, then pushes the water back out. The baleen works like a giant comb, trapping the food inside so the whale can swallow it. Blue whales and humpback whales are baleen whales.

The second group is the toothed whales. As you might guess, these whales have teeth and hunt larger prey like fish and squid. Dolphins and porpoises belong to this group, and so does the mighty sperm whale, which dives deep to hunt giant squid in the dark.

Songs of the Sea

Some whales are famous for their songs. The humpback whale is the greatest singer of all.

A male humpback can sing for hours, making long patterns of moans, squeaks and groans. These sounds travel a very long way through the water, so other whales can hear them far across the ocean. Whales in the same area often sing similar songs, almost like sharing the same tune.

Whales also use sound to find their way and to talk to each other. Toothed whales send out clicks and listen for the echoes that bounce back. This is called echolocation, and it helps them find food and avoid danger, even in dark or muddy water.

Deep Divers

Whales are champion divers. While we can hold our breath for less than a minute, whales can stay underwater for a very long time.

The sperm whale is one of the best divers in the world. It can dive deeper than a kilometre into the cold, dark ocean and hold its breath for over an hour while it hunts. Its body is built to handle the heavy weight of all that water pressing down.

Whales must still come up to breathe, so they cannot stay under forever. And because they have to keep breathing, whales never fall fully asleep. Instead, they rest one half of their brain at a time, while the other half stays awake to remember to breathe.

Why Whales Matter

Whales are not just amazing to look at — they help keep the whole ocean healthy.

When whales feed deep down and come up to breathe, they bring up nutrients that help tiny ocean plants grow. These tiny plants make much of the oxygen we breathe and feed huge numbers of sea creatures. So in a way, whales help the entire ocean stay alive.

Long ago, people hunted whales in such large numbers that some kinds nearly disappeared. Today, most countries protect whales, and their numbers are slowly growing again. But whales still face dangers from plastic in the sea, loud ships and fishing nets.

We can all help by keeping the oceans clean and supporting the people who work to protect these gentle giants.

What We Learned

We have journeyed across the oceans to meet the mighty whales.

We learned that whales are mammals that breathe air, stay warm and feed their babies milk. We met the blue whale, the largest animal that has ever lived, and discovered the two big groups: baleen whales that filter tiny krill, and toothed whales that hunt fish and squid. We listened to the humpback's song, dived deep with the sperm whale, and found out why whales matter so much to the health of the sea.

The ocean is full of wonders, and the whales are among its greatest treasures. Let's do our part to keep their watery home safe.

Want to explore more of the sea? Dive into Our Amazing Oceans, or go even deeper with Explorers of the Deep Sea.