Question 2 of 21

What is a coral reef?

... Coral reefs are made mainly from stony corals and are supported by the limestone skeletons they discharge.

Question 3 of 21

How long will it be until an estimated 70 percent of coral reefs disappear?

... It is estimated that this will happen within 40 years.

Question 4 of 21

Does a coral reef contribute to the environment?

... The reef buffets coastal regions from powerful waves and storms.

Question 5 of 21

How big is a single coral?

... It is only 3 millimeters long.

Question 6 of 21

What is a polyp?

... A polyp is an individual coral

Question 7 of 21

Is the coral a plant?

... The coral, although it is fixed to one spot, is a living creature.

Question 8 of 21

What does sessile mean?

... The term comes from the Latin for "sitting" and means without a stalk, attached at the base; in other words fixed in place. It usually refers to plants but also to corals, barnacles and mussels.

Question 9 of 21

Why did scientists originally think corals were plants?

... When branching corals spread out their tentacles, they resemble trees with branches.

Question 10 of 21

What is common to the jellyfish, sea anemone and the coral?

... They are all related and are carnivorous.

Question 11 of 21

Since it cannot move from place to place, how does the coral hunt for prey?

... It is a passive hunter, capturing small fish and other marine life that happens to encounter its tentacles waving gently in the current.

Question 12 of 21

Why could you consider a coral a half-plant?

... There are algae living in the cell walls supplying it with byproducts of photosynthesis, which the coral turns into proteins, fats and carbohydrates.

Question 13 of 21

What do algae gain from coral?

... The coral offers shelter and provides the algae with carbon, nitrates and phosphates they need.

Question 14 of 21

What is this useful arrangement known as?

... This mutually beneficent arrangement is known as symbiosis.

Question 15 of 21

What is the substance the polyps secrete?

... They secrete calcium carbonate or limestone.

Question 16 of 21

To what use is this substance put?

... The limestone creates a protective skeleton and a hollow chamber into which the polyps retreat in time of danger.

Question 17 of 21

How many polyps can be found in a single branching coral?

... A single branching coral can have thousands of individual polyps.

Question 18 of 21

When polyps join together into a colony what happens to them?

... The whole colony operates as a single organism.

Question 19 of 21

Do polyps reproduce?

... Polyps reproduce both by dividing thereby producing identical clones (asexually) or by sending out eggs or sperm (sexually).

Question 20 of 21

How is a new colony formed?

... New coral polyps sink downwards until they reach a hard substrate to which they can become attached. They can join an existing colony or reef or begin a new project.

Question 21 of 21

What do coral reefs need to survive and flourish?

... They require sunlight, and warm water of a certain salinity.