The quick answer
The biggest animal in the world is the blue whale. It can grow up to about 30 metres long. As far as scientists know, it is the biggest animal that has ever lived, even bigger than the dinosaurs.
RankiTanki, you know I love big numbers. What is the biggest animal ever? A dinosaur?
TankiGood guess, but no. Did you know? The biggest animal of all is alive today, and it lives in the sea.
Meet the blue whale
The blue whale is the biggest animal on Earth. A fully grown blue whale can be up to about 30 metres long. That is nearly as long as 3 buses parked in a row. Even a baby blue whale is longer than a car.
Blue whales are very heavy too. A big one can be heavier than 20 elephants put together. As far as scientists know, no dinosaur was ever that heavy. That makes the blue whale the biggest animal that has ever lived.
Why it can grow so big
Scientists think the sea is the secret. Water helps to hold up the whale’s heavy body. On land, an animal this heavy would find it very hard to move. In the sea, the blue whale glides along easily.
A blue whale is not a fish. It is a , like us. It breathes air through two on top of its head. A mother blue whale feeds her baby with milk.
Giant animal, tiny food
You might think the biggest animal eats the biggest food. But blue whales eat some of the smallest animals in the sea. Their food is , tiny shrimp-like animals about as long as your little finger.
A blue whale has no teeth. Instead, it has long, bristly plates in its mouth called . The whale takes a huge gulp of water full of krill. Then it pushes the water out through the baleen. The krill stay inside, like pasta in a .
Scientists think a blue whale can eat millions of krill in a single day. That is a lot of tiny snacks.
RankiSo the biggest animal eats tiny food all day. That is like eating a mountain of sprinkles for dinner.
TankiYes. Except these sprinkles can swim.
Other animal record holders
- The African elephant is the biggest animal on land.
- The giraffe is the tallest animal. A big one can be taller than a double-decker bus.
- The whale shark is the biggest fish. It is gentle and eats tiny food too.
- The ostrich is the biggest bird. It cannot fly, but it can run very fast.
Try it
Measure a blue whale with big steps
You need
What to do
- Go to a big open space with a grown-up.
- Put down the first marker. This is the whale’s nose.
- Ask the grown-up to walk in a straight line with big steps, each about 1 metre long.
- Count the steps out loud. After 30 steps, put down the second marker. This is the tail.
- Now walk from nose to tail with your own steps. How many do you need?
- Look back along your whale. That is how long a big blue whale can be!
Ask a grown-up to help you with this one.
Ranki30 metres is my new favourite big number. And the biggest animal ever is swimming around right now.
TankiBig body, tiny snacks. The blue whale is full of surprises!
Big words
- newborn
- Only just born.
- mammal
- An animal that breathes air and feeds its babies with milk.
- blowholes
- Nose holes on top of a whale’s head, used for breathing.
- krill
- Tiny animals that look like shrimps and live in the sea.
- baleen
- Long, bristly plates in some whales’ mouths that catch food like a sieve.
- sieve
- A kitchen tool with tiny holes that lets water through but keeps food in.
Quick quiz
1. What is the biggest animal that has ever lived, as far as scientists know?
The blue whale is heavier than any dinosaur scientists know of.
2. What do blue whales eat?
Blue whales eat millions of tiny krill, which they catch with their baleen.
3. Which animal is the tallest?
The giraffe is the tallest animal. A big one can be taller than a double-decker bus.
For parents and teachers
Blue whales were hunted almost to extinction in the 20th century and are now protected, and their numbers are slowly recovering in some oceans. Why marine animals can grow so large, thanks to buoyancy, plentiful food and efficient filter feeding, makes a good discussion about how where an animal lives shapes its body.
Pictures marked “AI generated” were made with AI tools. Ranki and Tanki are AI generated characters. Found a mistake? Write to info@pr-geo.com and we will fix it.
