Why are coral reefs colorful?
Short answer
Pigments in corals, algae, fish, and other organisms reflect different colors of light.
How it works
Coral colors can change with conditions. Prolonged stress such as unusually warm water can cause bleaching when symbiotic algae are lost.
Key point
The practical point is this: Prolonged stress such as unusually warm water can cause bleaching when symbiotic algae are lost.