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Coral Reefs 101 | National Geographic

National Geographic

2.3M views 9 years ago

Warm-up Questions

What pictures or animals do you think you will see in a video called “Coral Reefs 101”?
Why do you think coral reefs are important for the ocean?
What problems do you think coral reefs face today?

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Coral Reefs 101 | National Geographic

What coral reefs are (and how they are built) (00:00 – 01:27)

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1. What are corals, according to the video?

Fish that live in colonies
Animals made up of tiny polyps
Rocks that algae paint different colors
Colorful plants that grow in the ocean

2. How do polyps protect and support their soft bodies?

They stop moving during the day
They secrete limestone skeletons (calicles)
They build nests from seaweed
They hide inside shells left by other animals

3. What happens when polyp calicles connect to one another?

They become stinging tentacles
They dissolve and become ocean sand
They create a colony that acts as a single organism
They turn into algae inside the coral tissue

Coral Reefs 101 | National Geographic

Biodiversity and color: why reefs are full of life (01:27 – 02:36)

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1. About how much of the ocean floor do coral reefs cover?

More than half
About one quarter
About ten percent
Less than one percent

2. What gives coral reefs their rainbow of colors?

Minerals from volcanic rock
Different kinds of fish swimming around them
Algae that live in their tissue
Colored sand trapped in the reef

3. What can happen when coral is stressed by pollution or other factors?

It changes into a different species
It moves to deeper water to cool down
It grows faster because it gets more nutrients
It evicts its algae, leading to coral bleaching

Coral Reefs 101 | National Geographic

Coral as a climate record and threats to the future (02:36 – 03:53)

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1. Why can coral skeletons provide a “window to the past”?

They always keep the same thickness every year
They record sounds of ancient sea animals
They form layers like tree rings that reflect ocean conditions
They contain trapped air bubbles from ancient storms

2. What do warming waters cause, according to the video?

Instant recovery of coral after bleaching
More algae staying in coral, making reefs stronger
Prolonged coral bleaching that can kill reefs or make them vulnerable
A decrease in ocean salinity that protects reefs

3. What could happen by the end of the century without significant action on climate change?

Coral reefs will become completely invisible
Oceans could lose many of their colorful reefs
Coral reefs will move to freshwater rivers
All reefs will double in size

Coral Reefs 101 | National Geographic

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1. Which idea best summarizes how coral reefs form?

Fish build reefs by stacking rocks and shells
Reefs are underwater plants that turn into stone
Tiny polyps build skeletons, form colonies, and over long time create reefs
Single large coral animals grow quickly into reefs in one year

2. Why are coral reefs important ecosystems in the video?

They have no relationship to other ocean life
They are home to many marine creatures and provide habitat for young fish
They cover most of the ocean floor
They only matter because they are beautiful

3. What is one major cause of coral reefs being in danger, according to the video?

Climate change and warming waters
Too much sunlight from the moon
Too many coral predators eating all reefs every day
A lack of ocean currents

Discussion Questions

Discuss the ideas from this video

Coral Reefs 101 | National Geographic

Why do you think coral reefs can support so many different marine creatures even though they cover a small area?
What are some human actions that might stress coral (for example, pollution or climate change), and what could be done to reduce that stress?
How is coral bleaching connected to the relationship between coral and algae?
If a community relies on reef fish for food, how might coral loss affect people’s lives and local economies?