Grade 5
Lesson 4
Marine mammals - Bottlenose Dolphins
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Bottlenose dolphins

Most dolphins you see in animal parks are bottlenose dolphins. You have probably seen them in the movie Flipper too. Bottlenose dolphins live together in groups and love to play with other dolphins and with things they find in the water, such as pieces of seaweed or driftwood. Their favorite game is chasing boats. They love to “surf” the waves made by boats, and the higher the waves, the more fun they have!

Jumping dolphins

Some dolphins are real champions at jumping.

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How heigh can they jump?

They can jump up to 5-6 meters out of the water
5-6
meters

How do they breath?

Dolphins do not breathe through their mouths. They use the blowhole on top of their head instead. Whenever a dolphin goes under water, it holds its breath and keeps its blowhole shut.

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How long can they hold their breath?

After returning to the surface, the dolphin exhales strongly. Then, it inhales right away and dives down into the water once more.

Dolphins can hold their breath for almost 10 minutes
10
minutes

How do they sleep?

Dolphins sleep with their head above water so they can continue breathing through their blowhole.

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How do they see?

Under water, dolphins swim with their eyes open. Our eyes would start burning because of the salty water. Dolphin eyes have a special, thick slimy membrane over their eyes that does not allow
any salty water in.

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How do they heir?

Dolphins perceive sound through their tiny ears, located right behind their eyes.

They can hear much better than we can. Very often, they hear sounds that we are not even aware of.


How is the skin?

Bottlenose dolphins have smooth skin. Instead of fur to keep their body warm, they have a layer of fat (blubber) under their skin. Because their skin is so smooth, they are able to swim very fast.


They can swim 40 kilometer per hour.
40
kilometer per hour

Playing dolphins

Sometimes, you may notice little scratches on their body. That is because sometimes they bite each other with their sharp teeth during play. Dolphins also caress each other gently whileplaying. They love it, especially around their nose and pectoral fins and on their belly. 

How about the sonar?

Under water, dolphins make a lot of clicking sounds that sound like squeaks or a creaking door. Those clicks bounce off objects, such as fish, and the dolphin perceives the echo with its ears. That way, it knows where to find the fish. These sounds help these animals to find their way in the water.

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Where do they use the sonar for?

These sounds help these animals to find their way in the water. While we can see the difference between shark, a fish, coral or a rock, dolphins can hear it.. They can find their way even blindfolded.                                                                                             

Sonar is kind of a sixth sense.



The sonar

Other whales and bats also use sonar. Besides sonar sounds, dolphins also make singing and whistling sound.

By the way, dolphins do not use their mouth to make sounds like we humans do, because they do not have any vocal chords. The sounds come out of their blowhole instead.

What do they eat?

Bottlenose dolphins eat fish, such as herring, mackerel or capelin. Sometimes they also have crab or squid on the menu.

Bottlenose dolphins have about 100 teeth in their mouth, which they use to grab food, so slippery fish cannot get away.


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How do they eat?

Dolphins swallow their food whole, without chewing. To us, fish usually stink, but dolphins cannot smell, although they can use their tongue to taste the fish to see if it is delicious. Fortunately, dolphins have a very large stomach, so they can eat fish with bones and all!

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