A coral reef is the product of tiny animals—invertebrates related to jellyfish. Inside the tissues of coral animals live microscopic algae that provide all of the dazzling colors associated with reefs. Sometimes, coral animals lose their algae, a condition known as bleaching because the coral suddenly looks white. In recent years, bleaching has affected more and more reef systems all over the world.

What do scientists think is causing coral bleaching?
A.
pollution from chlorine dumping
B.
overfishing around the reef
C.
cooler ocean temperatures
D.
warmer ocean temperatures
answer
D.
warmer ocean temperatures

The coral polyp is an organism which colonizes with other members of the same species to form coral reef of hard skeleton of calcium carbonate. These organisms forms a mutualistic relationship with the algae called as zooxanthellae. The algae share oxygen, food prepared after photosynthesis and also provides them with color and the algae obtains shelter from the coral population.

Coral bleaching is a phenomena of removal of the algal colony from the surface of the coral reef. This occurs due to the change in temperature of the oceanic water. The increase in the temperature of the oceanic water swells up the algae and this leads to the removal of the algal colony from the coral reef. The coral reef get exposed to the external water environment becomes white due to loss of the algal colony from the surface. This is a kind of natural bleaching effect.