Create an animated lesson
On requestThis article is free to read. Creating a lesson uses your daily or stored credits; review the language and settings before starting.
How does a coral reef form?
Quick answer
A coral reef works as a living structure built by tiny animals called coral polyps, which secrete hard skeletons that pile up over centuries. Living coral relies on algae inside it for food, creating a vibrant ecosystem that shelters a quarter of marine life.
Step by step
- Coral polyps are tiny animals that build hard limestone skeletons.
- Over time these skeletons accumulate into massive reefs.
- Algae living inside the coral feed it through photosynthesis.
- Reefs shelter about a quarter of all ocean species.
- Heat stress makes coral expel its algae and 'bleach,' which can kill it.
People also ask
Are corals animals or plants?
Corals are animals — tiny polyps — though they host algae inside that make food by photosynthesis, blurring the line.
What is coral bleaching?
When stressed by heat, coral expels the colorful algae it depends on, turning white and starving; prolonged bleaching can kill the reef.
Why are coral reefs important?
They harbor a quarter of marine species, protect coastlines from waves, and support fishing and tourism for millions of people.
Part of the guide: Nature & Earth: Living Things and Rocks →