节目资讯
刊物:空中英语教室
日期:2012-07-11
难易度:Low
关键字:rain forest, colony, generation, shallow, coral reef, ecosystem
Welcome back, friends.
You know, coral looks like rock.
But it's not.
It's a living animal.
And as a matter of fact, a coral is related to a jelly fish.
Both have special cells to protect itself and capture prey.
And neither have a backbone.
OK, let's dive back into the lesson on line 10.
Our Coral Reefs.
The rest of it is made up of the bodies of earlier generations of coral.
Coral comes in many different shapes - round, branchlike or even flat.
Coral gets its food from tiny creatures, called "plankton," that flow by and
also from algae.
Algae grow on the coral and bind it together to create a reef.
The algae give the reef its different colors.
Normally coral reefs grow in shallow water where sunlight can reach the algae.
In warm, tropical water, reefs can grow strong and healthy.
Many different ocean creatures can find food and a home in them.
Coral is a fascinating and beautiful creature.
We've seen how much of the ocean floor they cover and just how many fish can
live there.
And now we're learning a little bit about how it grows.
Just before the break, we saw that only the outside layer of coral is alive
while all of the rest underneath it is not.
How does that work?
Well, the rest of it is made up of the bodies of earlier generations of coral.
So if you can imagine, the coral is just a thin layer at first.
And as it gets older, that layer dies, and the next layer is alive.
And as that one dies, the next one grows on top of it.
So it gets thicker and thicker, kind of like a tree, how a tree grows in... in
the circumference around and around and around.
That's how coral works.
OK, yeah, you just used the word circumference.
That means the length of a space around a circle.
OK, so. Here we're... though, we're looking at the generations of coral that
grow.
And the word "generation" simply means a group of people or a group of animals
that are the same age, or alive in the same time.
So earlier generations would be those that came before.
And they were alive at the same time, they probably died around the same time.
And then the next generation would grow on top of it.
Now coral comes in many different shapes.
It can be round, branchlike or even flat.
OK. Well, I know what round is and flat.
But what about branchlike?
Well, if you picture a tree, we have a tree that has lots of branches on it.
Those are the smaller pieces that come out from it.
And that's how the coral would be shaped as well.
OK. So the coral kind of comes out with all these little fingers, kind of shaped
like tree branches.
So how does coral eat?
Well, coral gets its food from tiny creatures called "plankton." And these
creatures don't actually swim around.
They're very, very... very small.
They flow by.
They're the current... the water actually moves the plankton around.
And the coral eats that.
Yeah. Well, when something flows, it moves very smoothly.
So the water goes by and carries these plankton, tiny little plants and animals
right by the coral, and they can eat it.
What else do they eat?
Well, they also eat algae.
An algae is what can grow sometimes...
If you have a fish tank, you can see algae growing in your fish tank, and you
have to clean that off.
Here's another way the coral reefs are useful is they... they eat the algae so
that it's not taking over.
Right. Algae is a type of plant, but it's so small that usually it just looks
like a lot of green stuff covering rocks and things underwater.
That's right.
If you step on it or touch it underwater, it's usually very slippery.
You can fall.
It's kind of slimy.
Right. Now the algae actually will grow on the coral, and they bind it together
to create a reef.
OK. So as the algae is growing on individual pieces of coral - we know it's a
small animal, so it's a... just in one place.
Now the algae, because they're growing to eat it, they connect it.
And that's how we get the reef.
We get the shapes that create these large areas instead of just one plant.
Yeah, yeah, instead of just a lot of little pieces, they bind it, or like you
say, connect it all together to make one big reef.
That's right.
Now the algae give the reef its different colors.
Often we think of coral reefs are being very beautiful with bright colors and...
we think that's the coral.
Actually, Ryan, that's the algae.
Oh, I actually didn't know that before.
I learned that from this article.
I always thought it was the coral that had the colors.
But that makes sense because sometimes if coral dies, it turns white.
OK. So the algae is what's growing on top of it and gives it its colors.
Now normally coral reefs grow in shallow water where sunlight can reach the
algae.
We know algae is a plant.
And we know plants need sunlight to grow.
So it's in shallow water so the sunlight can reach it.
Right. That's why you don't find coral in deep water.
You only find it in shallow water.
Now the word "shallow" means not deep.
It's a very short distance from the top to the bottom.
That's right.
So you could probably stand in it, or you can swim in it easily.
And it wouldn't take long to get to the bottom of the ocean.
Right. And so here the sunlight actually doesn't need to go very far in shallow
water.
So the algae can grow; it can get that sunlight.
Now in warm, tropical water - tropical meaning it's in a certain area of the
world that gets a lot of sunlight, and gets a lot of rain but also is very warm.
So the water would stay warm.
Yeah. And in these areas, the reefs can grow very strong and very big and very
healthy.
That's right.
That's because there is enough sunlight.
There is enough in the water, enough nutrients in these tropical regions.
Now many different ocean creatures can find food and a home in these coral
reefs.
Yeah. Coral reefs provide food for many different kinds of fish and animals that
live there.
But since they grow in such big structures, they also provide a home.
That's right.
I can't help but think of the movie Finding Nemo when we're talking about coral
reefs and all the colors and animals that live and find their home in the reef.
Sounds beautiful! I think I might want to go visit these coral reefs.
But we'll have a chance to talk about that more tomorrow.
For now, let's watch the skit.
Look at you.
You're so beautiful!
You are too.
But what exactly are we?
We are coral.
Coral?
Yes, small living animals.
We live together in colonies.
Oh, colonies?
Yes. Our colonies are called the rain forests of the sea.
Whoa, it sounds important.
Yes! We cover only 1 percent of the ocean floor.
But we support 25 percent of ocean life.
We are important.
There are a lot of us living on this reef.
Yes. But only the outside layer of the reef is alive.
Oh. What about the rest?
The rest is made up of earlier generations of coral.
May they rest in peace.
Hey, does all coral look alike?
Oh, no.
Coral comes in many different shapes and colors - round, branchlike, even flat.
Wow!
Hey, I'm getting hungry.
Can we go out to eat?
No. Our food comes from tiny creatures called "plankton." It just flows by.
Oh. That's convenient.
And sometimes we eat algae.
Oh... bless you.
I didn't sneeze. Hachoo.
I said we eat algae.
Oh, yuck! I don't like algae.
I love it.
After a while, it grows on you.
Algae gives coral reefs their beautiful color.
Hey, let's go out to where the water is deep.
No. We normally stay here in the shallow water.
Why?
This is where we grow strong and grow healthy.
Oh, yeah, I want to grow strong and healthy, just like you.
Little coral, you're adorable.
Hi, everyone. I'm Michelle.
(Chinese).
And that concludes our Language Tips today.
I'll see you tomorrow.
Bye-bye.
Coral reefs are amazing.
In and of themselves they are marvels of nature.
Their weird shapes and exotic colors are absolutely fantastic.
But coral reefs are also amazing because of what they do.
They provide food and protection to 1/4 of all ocean life.
Go on and say it with me: Amazing.
Well, we can't talk about coral reefs and not talk about their relationship with
humans.
And that, my friends, will be the focus of tomorrow's lesson, so.
Join us.
And as always, have an amazing day.