Question

Just what is coral? What kind of creature creates coral?

What are zooxanthellae? What significance do algae have in the formation and health of coral reefs? How does this affect the ocean depth at which corals can remain healthy?

Coral reefs have existed for millions of years, but all modern coral reefs are no more than 10,000 years old. Why? In other words, what happened to cause the deaths of the ancient coral reefs 10,000 years ago? You're looking for a pretty specific answer here. NOTE: There was nothing going on with respect to human civiliazation 10,000 years ago that could have had any impact on the world's coral reefs.

Following the Coral Reefs Plundered Around the World link, read about concerns about coral reef health. What ecological problems are threatening the world's reefs?

How could the death of a coral reef, which is just below the surface of the water, affect the lives of organisms living in the depths of the open ocean? You probably won't find this answer; you'll have to think about it.

Why should we care about the loss of the coral reefs? This question relates both to the "what use are they?" issue, and to broader, less selfish issues.

Finally, what can one person do to help reduce the assault on coral reefs?

Answer 1

Few marine coelenterates secrete their exoskeleton in the form of some hard stony substance which forms reefs in the warm seas is called coral reefs.

Marine coelenterates which belong o the class Anthozoa live in compact colonies of many identical individual polyps form corals.

zooxanthellae is a dinoflagellate which is yellowish brown in color which lies in the cytoplasm of many marine coelenterates forming a symbiotic relationship.

Healthy tropical coral reefs grow horizontally from 1 to 3 cm per year, and grow vertically anywhere from 1 to 25 cm (0.39 to 9.84 in) per year however, they grow only at depths shallower than 150 m (490 ft) because of their need for sunlight, and cannot grow above sea level

One of the main threats to coral reefs is the temperature rising in seawaters. When the temperatures get too warm for the coral, their symbiotic microalgae breaks down and they are unable to form corals. This is the reason why modern coral reefs are no more than 10,000 years old.