Why Are Blue Whales Endangered? - Lesson for Kids

Instructor: Jenny Homer

Jenny has masters' degrees in public health and public administration.

In this lesson, we'll learn about the biggest animal in the world, the blue whale. Find out why these amazing creatures became endangered and what threats they face today.

What Is the Blue Whale?

Did you know that there is a living thing on Earth today that is heavier than the biggest dinosaur and as long as a full-size basketball court? This incredible animal is the blue whale!

Because they're mammals, blue whales can't breathe underwater and have to come to the top of the water to breathe air. Blue whales eat enormous amount of krill, a tiny animal similar to shrimp. When blue whales eat they first take a giant gulp of water that's full of krill. Their tongue pushes the water out, while baleen plates (pieces of fringe in their mouth) hold the krill in.

Blue whales live in colder waters during the summer and swim to warmer waters in the winter. Today there are between 10,000 and 25,000 blue whales in the world's oceans. These may seem like big numbers, but blue whales are endangered. Since the late 1800s, several hundred thousand have died because of activities by people.

Size of a blue whale


Whaling is hunting and killing whales. The speed and weight of blue whales made it hard for whalers to catch them at first. But in the early 1900s, whalers designed new weapons and tools, and they began catching thousands of blue whales every year.

Whaling became a big business, where people wanted whale oil to use for soap, candles, lamps, and margarine. They used other parts for meat and fertilizer. In 1966, the International Whaling Commission made it illegal to hunt blue whales.

Blue whale

Threats Today to Blue Whales

Whaling is illegal today, but blue whales face other threats. They are:

  • Boats - Blue whales can be killed or injured if they are hit by boats. In 2007, three blue whales died in a very short period of time near California after being hit by boats.
  • Noise pollution - Blue whales make loud noises to communicate with each other from very far away. Unfortunately, people also make a lot of noise (anthropogenic noise) with their boats and when drilling for oil and gas. It may be harder for blue whales to hear each other because of anthropogenic noise.
  • Bycatch - Blue whales can be hurt when they get tangled up in fishing lines used to catch other kinds of fish.
  • Climate change - Warmer temperatures in the ocean may affect the number of krill blue whales have to eat.
  • Pollution - Chemicals that people dump in the ocean can make blue whales sick or ruin the water where blue whales swim.

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