About Coral Reefs

Coral Biology

Individual corals are known as polyps. They have a small, simple biology within their beautiful exterior–a simple stomach-mouth system, and the mouth is a tentacle extending out from them. The polyp is the center of the universe, so to speak, as it is the basic building block of a coral colony. These colonies form into reefs, which are, then, millions of tiny animals coexisting together.

The coral polyps eat only at night, as if they are shy in the light to eat. They feed off of plankton that they sting with their tentacles and ingest, and then release their food in the form of calcium carbonate. They also subsist on microscopic algae called Simbiodinium, which live inside the coral and help it to sustain life, growing bigger and stronger. This calcium is what forms their beautiful, hard exterior.

There are basically two types of coral, soft corals (octorals) and hard corals (also called “stony corals”). The two types of coral are vastly different with hard corals being the only one with a hard exterior, which is made up of gorgonin, a protein, and calcium carbonate. Soft corals are tentacle creatures, with eight tentacles to be exact, which is why they are called “octorals.” There are many species of each.

The Three Types of Coral Reefs

Reefs are distinguished from one another by their size, structure, and location. For example, reefs close to shore that extend outward like platforms are called fringing reefs. Barrier reefs are separated from landmasses by wide bodies of water and travel along the same directions of the coastline. Atolls are circular coral reefs. They always surround by an island with a lagoon separating them. Atolls are typically found only in the Indian and South Pacific oceans.

Feeding and Sexual Reproduction of Corals

Interestingly, corals reproduce both sexually and asexually. When coral reefs divide into individuals, this is known as asexual reproduction. Sometimes, however, corals undergo a mass spawning where polyps release millions of eggs and sperm all at the same time. The spawnings are set with the cycles of the moon. A small percentage of fertilized eggs settle back down upon the reefs and form new coral colonies.

Most corals begin as clear animals with white skeletons, like white human bones. However, the buildup of zooxanthellae that live in these corals produce pigments that are visible through the clear bodies of these polyps and are what causes the beautiful colors of coral.

The Coral Triangle


The Coral Triangle is a specific oceanic region which contains over 500 species of living corals and has the highest marine diversity in the entire world. The Coral Triangle expands over six million square kilometers, and its spectacular coral reefs systems are home to thousands of dolphins, sharks, rays, and six species of sea turtles.

The coral triangle spans six countries including the Philippines, Solomon Islands, Timor Leste, Indonesia, Malaysia, and Papua New Guinea. The coral triangle is the richest area of coral and marine diversity in the world.

Biodiversity and the Coral Triangle

Globally-renowned coral expert, Dr. Charlie Veron, calls the Coral Triangle, “the centre of Earth’s marine diversity.” The Coral Triangle alone has some 600 species of coral, which is 95% of the world’s total of corals. What is interesting about the Coral Triangle is that it has the highest fish diversity in the entire world. In fact, 37% of the world’s total species of fish are represented here. There are a whopping 2, 228 species (and counting) of fish here. The area also contains six out of seven of the world’s species of sea turtles. The area also has a large population of tuna, supplying a lot of the world’s multi-billion dollar tuna industry.

The Coral Triangle is also one of the few places frequented by the Blue Whale, the largest animal to ever live on the earth (yes, even bigger than all of the dinosaurs) and the endangered dugong. Also, sperm whales, porpoises, dolphins, all call the coral triangle home.

Also, the coral reef houses the one animal linking us to the dinosaur age—one which was thought to be extinct for 70 million years, the Sulawesi Coelacanth (Latimeria menadoensis), a living relic of the Dinosaur era, thought to have been extinct for some 70 million years.

Sulawesi Coelacanth

Sulawesi Coelacanth

The Coral Triangle supports more than 120 million people who depend upon it for food and monetary income. However, overfishing, destructive fishing, and the illegal fishing and harvest of endangered marine species, not to mention global warming, are all taking their toll on these fragile ecosystems.

Corals: The Medicine Cabinet of the 21st Century

Eastern cultures in the 14th century recognized the medicinal benefits of seahorses and organisms found in corals. Today, scientists are just beginnings to realize the medicinal value of species of corals and marine animals found here. Today, chemical extracts found in coral sponges are being use to make AZT the drug that fights and prevent the spread of HIV into AIDS and ARA-A a cancer fighting agent, are both found in extracts of corals. Other marine animals here such as the choral whip and some snails, as well as extracts from Japanese and Caribbean coral reefs are being studied for their ability to cure pain, stop infections, and treat cancer, heart disease, and bacterial infections. One organism found in a Japanese reef may lead to a cure for Huntington’s Chorea, a fatal nervous system disease. Cone snails, for example, release powerful toxins that are being researched as new painkillers.

An Economic Ecosystem

Coral reefs are important to sustain marine variety, to provide food for the world, and to provide money, jobs, and entertainment for the world from to travel and tourism income. In fact, corals reefs provide billions upon billions of dollars for our economy through all of these ventures.

Travel and Tourism

Coral reefs are a commercial boon to the economy. The National Marine Fisheries Service estimates their value at over $100 million dollars to the world economy.


Coral Reefs help to feed one half a billion people every year. In fact, just one single square kilometer of coral reef can supply 40 tons of food in a year. Corals are home to much of the world’s favorite seafood items including tuna, grouper, oysters, and other seafood.

Half of all fisheries in the world depend upon coral reefs for a portion of their fishes. Local economies also receive billions of dollars from visitors to reefs through diving tours, recreational fishing trips, hotels, restaurants, and other businesses based near reef Coral reefs provide homes to most of our aquatic species, and many of those that feed us as well.

Coral Reef Endangerment

Despite their great importance to our economy and the feeding of so many people, one fifth of all of the coral reefs in the world have been lost, and because of the emission of greenhouse gasses, the coral reefs are predicted to completely disappear within this century. Also damaging to reefs are pollution, disease, and the destructive behavior of humans.

Once reefs are damaged, fish stop lodging there because they can no longer be sustained and fed by the corals. Consequently when they lose the beautiful fish, they lose divers, tourists, jobs for the people who work in tourism, and food for the world.

The results could be catastrophic for the fish that depend on corals for food and to people everywhere that depend upon reefs for fish to eat. The situation can create a famine, especially in third world countries that depend on this food as their sole source of protein. Fish will become a luxury good,” said Cassandra deYoung of the U.N. Food and Agriculture Organization, “You already have a billion people who are facing hunger, and this is just going to aggravate the situation. We will not be able to maintain food security around the world.


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