Name: 珊瑚礁是什麼，有什麼作用？ (What Are Coral Reefs And What's Their Purpose?)
Uploaded: 2021-01-14T05:37:46.000Z
Duration: 4 min 43 s
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Coral reefs are like the rainforests of the sea, and like those here on land, they're

進階被動語態

being destroyed. But why should you care?

Howdy friends under the sea, Trace here for DNews. When you picture coral you probably

see it like THIS[a] right? But coral aren't just colorful rocks. Tiny living things live

in there. Those "rocks" are actually the skeletons of polyps, which look like this[b]. Polyps

constantly secrete calcium carbonate to build these protective skeletons. This is why people

say coral reefs are living, not because the calcium structures are alive, but because

the polyps live inside those structures -- like a turtle in a shell -- only popping out to

feed or occasionally fight with one another.

Coral are related to jellyfish, and sea anemones and are not mobile animals, instead they anchor

and live their whole lives in one place. Polyps can be as small as the head of a pin or as

large as a foot across (30 cm) and while some grow in groups, others are solitary. The varied

colors in their bodies comes from symbiotic algae that live inside of them. As they grow

and die, more coral grow on top of them, and over millions of years, coral pile together

to form giant coral reefs that create the basis for 25 percent of ALL ocean life, even

though they're only point-one percent of the area of the ocean -- again, rainforest of

Coral appeared in the fossil record 400 million years ago. As the polyps grow through their

life cycle, the calcium carbonate they secrete will sometimes merge with the secretions of

other polyps around them, forming shapes. The polyps can form tables, pillars, spiral

wires, staghorns, and brain coral. They're all rigid structures with living polyps, but

they live in different places and require different conditions. These shapes are affected

by weather, currents and of course human and large animal activity. When coral like this

band together, they're called "reef building coral," and they form some of the most diverse

If you're like me, you grew up hearing the reefs were important, but I was never sure

WHY. After researching, I get it. I could list all the animals living in a coral reef,

but to be honest, this DNews episode would never end. There are literally millions of

species that subsist in, on and around coral reefs. They've been around for millions of

years, so it's safe to say there are likely fish, crustaceans and algae that evolved to

live on reefs and nowhere else, just like insects, mammals and birds in the Amazon.

Thats not all they do. Coral also control how much carbon dioxide is in the ocean. They

take the carbon dioxide out of the water, and use it to build their calcium carbonate

skeletons. Without coral, the amount of CO2 in the water would affect the whole planet,

but luckily, they trap that in stone for us all.

And if housing species, looking awesome, and saving the planet wasn't enough... Coral reefs

alter how the ocean affects the shore. Because they build up over millions of years, and

can survive live in warm shallow water as well as colder deeper water, reefs can span

massive areas and undulate like mountain ranges. They build themselves to withstand typhoons,

hurricanes and other tropical storms, and therefore buffer the shore against waves,

storms, and floods! These tiny animals evolved long before we did, and their existence in

areas like Australia and Florida can prevent loss of life, property damage, and erosion

Today, coral are in trouble. Because coral are so sensitive to water temperature, global

warming/climate change, ocean acidification, ecotourism and commercial overfishing are

beginning to kill off these tiny animals. In fact, when the animal is stressed, they

release their symbiotic colorful algae into the water, turn white and die. Which is why

it's important to think of coral not as pretty rocks but as living things like a dog or an

A new 42 year study of coral has found we've only got about a sixth of the coral left on

our planet -- with the Caribbean losing 50-percent of their coral since 1970. But all hope is

not lost, the parrotfish might be a coral savior. Where parrotfish live, coral are thriving,

so new sanctions on the protection of parrotfish are being considered. With a bit of effort

we can help these little animals continue another 400 million years, and it helps to

Do you know more about coral now? Want to know about something else?

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say hello. We love you guys, thanks for watching.