What Are Coral Reefs And What’s Their Purpose?

Coral reefs are like the rainforests of the
sea, and like those here on land, they’re 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 the sea. 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 ecosystems on our planet. 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. It’s mind-boggling. 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 by tempering the rushing ocean. 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 elephant. 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 get to know them a bit better, right? Do you know more about coral now? Want to
know about something else? Tell us in the comments and subscribe. Also,
come to Facebook, Twitter and GooglePlus to say hello. We love you guys, thanks for watching.

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