Colonies of tiny animals called polyps

What causes coral bleaching?

Heat stress makes corals expel their algae

Why are reefs important to people?

They protect coasts and support fishing and tourism

Coral Reefs Quiz: 10 Questions That Test What You Know

This coral reefs quiz covers coral polyps and their algae partners, fringing, barrier and atoll reefs, the Great Barrier Reef, reef fish, coral bleaching and efforts to save reefs. Ten questions test what you know about the rainforests of the sea.

Start Coral Reefs Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Animal
What are corals?
Partner
Which algae live inside corals and feed them?
Area
About what share of the ocean floor do coral reefs cover?
Types
What are the three main reef types?
Largest
What is the largest coral reef system?
Bleaching
What causes coral bleaching?
Triangle
Which region has the most coral biodiversity?
Sand
Which fish helps make white sand on reefs?
Threat
Which starfish can destroy large areas of coral?
Value
Why are reefs important to people?

Explanations: answer key for all 10 questions

Q1: What are corals?
Answer: Colonies of tiny animals called polyps
Each polyp builds a limestone skeleton.
Q2: Which algae live inside corals and feed them?
Answer: Zooxanthellae
They give corals much of their color.
Q3: About what share of the ocean floor do coral reefs cover?
Answer: Less than 1%
Yet they host about a quarter of marine species.
Q4: What are the three main reef types?
Answer: Fringing, barrier and atolls
Darwin described how they form.
Q5: What is the largest coral reef system?
Answer: Great Barrier Reef
It stretches about 2,300 kilometers.
Q6: What causes coral bleaching?
Answer: Heat stress makes corals expel their algae
Bleached corals can starve.
Q7: Which region has the most coral biodiversity?
Answer: The Coral Triangle
It includes Indonesia and the Philippines.
Q8: Which fish helps make white sand on reefs?
Answer: Parrotfish
It grinds coral into sand.
Q9: Which starfish can destroy large areas of coral?
Answer: Crown-of-thorns
Outbreaks are linked to nutrient runoff.
Q10: Why are reefs important to people?
Answer: They protect coasts and support fishing and tourism
Hundreds of millions depend on them.

Coral Reefs Quiz – Rainforests of the Sea

Coral reefs are built by tiny animals called polyps that live in colonies and build limestone skeletons. Inside their tissues live algae called zooxanthellae, which use sunlight to make food and give corals their bright colors.

Reefs cover less than 1% of the ocean floor but support about a quarter of all marine species. They come in three main forms: fringing reefs along coasts, barrier reefs separated by lagoons and ring-shaped atolls. The Great Barrier Reef is the largest reef system on Earth.

Reefs face serious threats from warming seas, which cause bleaching, along with pollution, overfishing and ocean acidification. Marine parks, cleaner water and coral restoration projects help, but cutting greenhouse gas emissions is key to their survival.

What This Quiz Teaches

This quiz is for students and divers learning about coral reefs.

What corals are
What zooxanthellae do
What reef types exist
What causes bleaching
Why reefs matter

Did You Know?

Some corals live for thousands of years.
Deep cold-water corals grow in darkness.
Coral spawning happens after full moons.
Reefs absorb wave energy.
Coral gardening helps restore reefs.