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Written by Administrator
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Monday, 03 July 2006 |
What is a coral reef?
Coral reefs are massive limestone structure that provides shelter for marine life. They are the gardens and forests of the sea. As one of the largest and most complex ecosystem on the planet, coral reef are home to approximately 25 % of the ocean's species. To imagine a coral reef, think of it as a bustling community, a city of the sea, with the building made of corals, and thousand of inhabitants coming and going, carrying out their business. | | | What is coral?
Corals look like a plant or a rock. But it is actually composed of tiny, fragile animals called polyp. There are two types of coral: hard corals and soft corals. Hard corals or reef-building corals are hard as rock. Their skeletons are made out of calcium carbonate. Hard corals need zooxanthellae for survival and only live in clear shallow water. Soft corals look like plants or trees. They are non-reef building corals and don't posses zooxanthellae. Soft corals can be found both in tropical seas and in cool, dark water. | | | A polyp is a simple creature. They do not have back bone or invertebrates, and are cousins of jellyfish. A polyp has a sack-like structure. At its free end is a mouth surrounded by numerous stinging tentacles called cnidae. The polyp extracts calcium carbonate from seawater to build a hard external limestone skeleton that protects the soft, delicate body of the polyp. | | How do corals eat ?
Some corals eat by catching tiny floating creatures called plankton. They extend their long stinging tentacles to capture plankton that float by the ocean currents. Coral polyps are generally nocturnal feeders. They stay inside their skeletons during the day, and come out to feed at night. Hard corals or reef-building corals derive their nutrition from zooxanthellae. | | | | What are zooxanthellae?
Zooxanthellae are single-celled algae that live and grow within the tissue of hard coral polyps. Zooxanthellae and coral have a symbiotic relationship and rely on one another for survival. Zooxanthellae provide the polyps with food through the process photosynthesis. In turn, coral polyps provide zooxanthellae a safe and protected home. | | | | | | How do corals reproduce ?
Corals exhibit sexual and asexual reproduction. Sexual reproduction occurs when the egg and sperm are released into the water. The sperm then fertilized the egg, creating new individual called planula or coral larva. The larva naturally attaches itself to a hard surface and become a coral polyp. In asexual reproduction, the coral polyp divides making an exact genetic copy of itself. | | | | | | | | How long does it take for corals to grow?
Corals need a long time to grow. In one year corals can grow about 1cm. In 100 years, massive corals may grow by only 1m. If a 5m coral is damaged, it can take up to 500 years to recover!!! | | | How old are coral reefs?
Coral reefs are one of the most ancient ecosystem on the earth. The first stages of coral reef evolution began 500 million years ago. Modern coral reefs have been in existence for over 50 million years. Some established coral reefs are between 5,000 and 10,000 years old. | | | | | | What destroys coral reefs ?
Coral reefs are fragile ecosystems and can easily be damaged or destroyed. Among the most destructive practices are blast fishing, the use of poison to stun fish and dropping anchor in coral. Coral can be damaged by just being touched and unaware divers and snorklers are often the culprits. Coral is also damaged as a result of pollution and siltation. Natural phenomena such as earthquakes and predation (for example, by the crown-of-thorns starfish) also damage the coral.
Crown of Thorns eating on coral, (c) Wolcott Henry 2001
| What can you do to help protect coral reefs ?  | Don't purchase items or souvenirs made from coral or other threatened marine life such as dried coral, pufferfish, or giant clam shells. | | Don't touch, stand on, or collect coral when you are snorkeling. | | If you are a diver, maintain control of fins, gauges, and other equipment so that they do not bump against the reef. | | If you have a tropical aquarium, make sure that you do not purchase fish caught using cyanide or other poisons. | | There is evidence that coral reefs may provide the base ingredients for new medicines | | Join an environmental organization that supports marine ecosystems |
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Last Updated ( Wednesday, 19 July 2006 )
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