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Big blue

Ellen Whyte

The giant of the seas

Blue whales live in oceans all around the world. Some live in their own neighbourhood and don't travel very far. Others travel for thousands of kilometres every year. Nobody knows why some stay at home and why others travel.

The blue whale is the biggest creature on Earth. Adults are usually 30 metres long and weigh about 150,000 kg. Some can grow to 33 metres and weigh 200,000 kg.

The biggest land animal is the African bush elephant. The largest ever found was 10.6 metres tall and weighed 12,272 kg.

Although big blue whales are easy to spot in the water, it's quite difficult to study these big mammals.

Blue whales usually swim at about 10 km/h. But when they want to, they can swim at speeds of 50 km/h. They also dive 100 metres below the surface to eat and can stay down for 10 or even 20 minutes. It's not easy to keep up with them.

Luckily, there are ways to tell blue whales apart. Their backs have different patterns of blue and grey. Many blue whales also have patches of yellow algae called 'diatoms' on their tummies. These different patterns act like fingerprints - each is unique.

True or false?

1 African elephants are smaller than blue whales.

2 Blue whales can stay underwater for more than five minutes.

3 Scientists can tell blue whales apart by their markings.

Karaoke king of the ocean

Find words that mean the following:

chant, very big, type of creature, shout

Blue whales like to make a lot of noise. When they dive underwater, they sing with loud moans and whistles.

People talk at about 60 decibels. A crying baby can yell at 90 decibels. But blue whale calls are louder than jet engines. A blue whale sings at 188 decibels. A jet engine roars at 140 decibels.

Although blue whale calls are too low for us to hear, other whales can hear them from 1,600km away. Blue whale ears are also enormous. Their ear bones are 30cm long; human ear bones are no bigger than 1cm.

Scientists think that blue whales don't just talk to each other but also to other whale species.

Gentle giants

Fill in the gaps with the following words:

endangered, interesting, gentle

Blue whales are the largest animals ever to live on Earth. They're even bigger than the biggest dinosaur.

Blue whales are very _______________. Divers can swim next to them quite safely. But as we can't dive and swim as well as these mammals, we use video cameras or 'crittercams' to see how whales live.

Crittercams are stuck onto the whale's back with a little suction cup. This means the whale doesn't even know it's there. The crittercam allows us to learn more about this _______________ sea mammal.

The more we learn about this beautiful, _______________ animal, the more effectively we can try to protect it.

Hong Kong sea mammals

To spot whales, you have to be out at sea. And although whales are very big, the ocean is even bigger, so spotting them takes some time. What's more, whales are quite rare in Hong Kong.

However, Chinese white dolphins and finless porpoises are much easier to spot. Like whales, these sea mammals are part of the Cetacean order.

Good places to spot Chinese white dolphins are western waters, including Sha Chau and Lung Kwu Chau Marine Park, around Lantau Island and Tuen Mun.

Good places to spot finless porpoises are southern and eastern waters. Try Lamma Island, Peng Chau, Cheung Chau, Waglan Island, Po Toi and the Soko Islands. Also try Sai Kung and Mirs Bay in the New Territories, and Shek O, Stanley, Cape d' Aguilar and Aberdeen on Hong Kong Island.

Endangered colossus

Find antonyms, or words that mean the opposite, to:

released, healed, forbidden, friends

Two hundred years ago, there were more than 250,000 blue whales. Today there are between only 10,000 and 25,000 left.

Because they are so big, blue whales don't have many enemies. Scientists have seen blue whales with scars made by killer whale teeth. But nobody knows if a killer whale has ever managed to kill a blue whale.

The biggest danger to blue whales is mankind. More than 90 per cent of blue whales worldwide were killed between the 1860s and the 1960s. Although the International Whaling Commission has banned all blue whale hunting, Iceland, Norway and Russia continue to kill them.

Blue whales are also killed when hit by ships and trapped in fisherman's nets.

Because whales have such sensitive hearing, many are injured by loud underwater sounds. Each year whales are hurt and killed by underwater drilling and military ships using sonar.

fab fact!

Blue whales eat krill, very small shrimp-like crustaceans about 1-6cm long. A hungry blue whale can eat 4,000kg of krill in a day. That's the equivalent of 64,000 hamburgers

fab fact!

The blue whale is nicknamed the 'sulphur-bottom whale' because of the yellow diatom algae that grows on the underside of their body

compare!

In the winter, blue whales swim to the equator to mate. Female whales, or cows, give birth to 8 metre-long calves a year later. Baby elephants are about 1 metre tall when they are born

now do this

Try to answer the following questions without referring to the text

1 Blue whales live in ...

a. tropical oceans.

b. polar oceans.

c. all oceans.

2 Adult blue whales are about ...

a. 300 metres long.

b. 30 metres long.

c. 3 metres long.

3 How many blue whales exist today?

a. 1,000 to 2,500

b. 10,000 to 25,000

c. 100,000 to 250,000

4 Which is loudest?

a. A crying baby

b. A jet engine

c. A blue whale

5 Blue whales eat ...

a. squid.

b. krill.

c. killer whales.

6 Baby whales are called ...

a. bulls.

b. cows.

c. calves.

Look online for more about blue whales

National Geographic

Watch videos of blue whales at sea, listen to their song, and read up on the latest discoveries about them.

Enchanted Learning Blue Whale

Quick facts, colouring printouts and puzzles useful for projects and for younger readers.

Protect Marine Life From Sonar

A short article and online video that explains how sonar injures and kills whales, dolphins, fish and other sea life.

Nat Geo Wild

You can see blue whales in Big Blue on Friday at 9pm and Saturday at 5pm on Nat Geo Wild.

See for yourself

Nat Geo is also holding an exhibition at IFC Mall featuring a life-sized baby whale. The exhibition opens on Friday.

Look out for our fabulous worksheets tomorrow, which you can take with you when you visit the exhibition.

Answers:

May 13

Dragon myths: 1. F, 2. F, 3. T

Flying snakes: rainforests, parachute, predator, prey

Green iguana: trees, pet, climb, whip, warn, drop

Komodo dragon: lizards, carnivores, cold-blooded

Gila Monster: famous, carrion, imagine

Quiz: 1. b, 2. c, 3. a, 4. a, 5. c, 6. b

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