🎬 Ocean Megabuilders (海洋巨型建造者)
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The bright colors of coral reefs can be seen in warm seas all around the planet.在地球各地温暖的海洋中都可以看到珊瑚礁的鲜艳色彩。
But they are not just beautiful. They are also hugely important to our oceans.但它们不仅仅是美丽。它们对我们的海洋也非常重要。
One, corals are actually animals.第一，珊瑚实际上是动物。
Though they may look like colorful plants, coral are in fact made up of tiny animals called polyps.虽然珊瑚看起来像色彩缤纷的植物，但实际上它们是由称为水螅体的微小动物组成的。
Polips can range from the size of a pinhead to a bit larger than a basket ball.Polips 的大小可以从针头大小到比篮球稍大一些。
Two, corals are mega builders.第二，珊瑚是巨型建造者。
Each polyp builds itself a skeleton out of limestone.每个水螅体都用石灰石为自己建造一个骨架。
These skeletons join together to form large colonies of hard corals.这些骨骼连接在一起形成大群的硬珊瑚。
As polyp colonies grow over hundreds and thousands of years,随着水螅体群体的生长数百年、数千年，
they join with other colonies and become reefs that can stretch over hundreds of kilometers.它们与其他殖民地结合在一起，成为绵延数百公里的珊瑚礁。
The largest coral reef is Australia's great barrier reef.最大的珊瑚礁是澳大利亚的大堡礁。
It began growing about 20,000 years ago.它大约在两万年前开始生长。
Three, coral reefs are some of the most diverse ecosystems on earth.第三，珊瑚礁是地球上最多样化的生态系统之一。
Though they cover less than 1% of the ocean floor, coral reefs are home to 25% of all sea creatures.尽管珊瑚礁只占海底面积不到 1%，但却是 25% 海洋生物的家园。
Up to 2 million species live in coral reefs around the world.世界各地的珊瑚礁中生活着多达 200 万种物种。
Four, coral provide a window to the past.第四，珊瑚为我们提供了了解过去的窗口。
As coral grow over thousands or millions of years, their limestone skeletons form layers.随着珊瑚生长数千年或数百万年，它们的石灰岩骨架形成层。
These are similar to tree rings.这些类似于树木的年轮。
They vary in thickness based on ocean conditions at the time.它们的厚度根据当时的海洋状况而变化。
Scientists can study these layers to learn what the earth's climate may have been like in the distant past.科学家可以研究这些层，以了解遥远的过去地球的气候可能是什么样的。
But what about the future?但未来呢？
Unfortunately, climate change is dangerous for earth's coral reefs.不幸的是，气候变化对地球上的珊瑚礁来说是危险的。
The animals that live there and the 500 million people around the world who depend on reef fish for food.生活在那里的动物以及世界各地以珊瑚鱼为食的 5 亿人。
Unless we can slow down climate change, scientists warn that our oceans could lose many of their colorful reefs by the end of the 21st century.科学家警告说，除非我们能够减缓气候变化，否则到 21 世纪末，我们的海洋可能会失去许多色彩缤纷的珊瑚礁。
Before You Watch
polyp · limestone · reef · symbiosis
While You Watch
Critical Thinking · Media Comparison. Which was a better source for understanding how coral reefs form: the video footage or the textbook diagrams? Why?
Vocabulary Review
Reading A: 10 Target Words
Reading B: 10 Target Words
🏆 Reading Explorer 2 · Unit 6 大满贯荣誉证书
6A 精读、6B 精读与 Ocean Megabuilders (海洋巨型建造者) 视频拓展