Blue Whales: Saving the Giants of the Ocean

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Students will read a passage about blue whales and threats they face in their ocean environment. They will then answer questions about facts, comparing and contrasting, central ideas, and themes.

Topic(s): Science. Skill(s): Summary, Compare & Contrast, Main / Central Idea. Genre(s): Informational


Blue whales are the largest animals on Earth. They are also the largest animals known to have ever existed. This means that they are bigger than the dinosaurs that lived millions of years ago. Blue whales weigh as much as 33 elephants (200 tons) and can be up to 100 feet long. A baby blue whale is called a calf. A blue whale calf drinks over 100 gallons of milk every day.

Blue whales can live as long as humans. They can live to be 80 to 90 years old.

Blue whales eat mostly small shrimplike creatures called krill. Because blue whales are so big they need to eat lots of krill. They eat about four tons of krill a day. That is like eating 32,000 hamburgers a day. Blue whales spend their summers in polar waters eating large amounts of krill. Then they migrate thousands of miles to tropical and subtropical waters to spend the winter.

Blue whales live alone or in pairs. They are not like other types of whales that live in groups known as pods. Blue whales make a variety of sounds underwater. Scientists believe they make these sounds to communicate with each other. They also believe some of these sounds act like sonar. The sounds help the whales map their ocean environment. Some of the sounds they make can be heard for hundreds of miles underwater.

The biggest threat to blue whales is humans. Blue whales are hunted for their whale oil. Blue whales almost became extinct during the early part of the 20th century. This means they would have disappeared from the Earth forever. In 1966, the International Whaling Commission banned blue whale hunting. But some countries ignore this ban and continue to hunt blue whales.

Blue whales also face other threats from humans in their ocean environment. Ships sometimes strike whales and injure them. Ships also produce ocean noise that makes it hard for whales to communicate. Ocean pollution and fishing are other dangers facing blue whales. They sometimes become tangled and trapped in fishing nets.

Blue whales are an endangered species. Endangered species are animals that are in danger of disappearing forever. Only 10,000 to 25,000 blue whales remain in the world’s oceans. It is important to protect blue whales because they play a key role in the ocean’s food chain.

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