Blue whale
The blue whale is the biggest animal in the world.
An adult blue whale is long – as long as 3 buses. It is heavy too – as heavy as 20 elephants. Its heart is as big as a car.
It has a big mouth but it just eats tiny animals called krill. As krill are so tiny, blue whales must eat lots of them.
Krill are about 2 cm long.
Photo of Antarctic krill by Uwe Kils. Licensed under CC BY-SA 3.0 via Wikimedia Commons
The blue whale is the biggest mammal in the world. As it is a mammal it must breathe air out of the water.
The blue whale uses 2 holes to breathe air. The holes are on top of its head. They are called blowholes.
Like all mammals, blue whales have bones.
A blue whale skeleton
But they do not have teeth! They have long, strong bristles. The bristles act like a curtain. There are tiny gaps between the bristles.
Photo by NOAA is in the public domain via Wikimedia Commons
After a blue whale scoops up lots of krill, it shuts its mouth. The gaps between the bristles let the water back out. But the krill are too big and are trapped in the mouth. Now the whale can gulp the krill down. Yum yum!
See the bristles in the mouth of a humpback whale.