Learn About Corals

What is a coral?

Corals may not look like it, but they are in fact animals. They are tiny, sessile (non-moving) creatures. A single coral organism is called a polyp; many polyps together are called colonies, and multiple species of colonies are called coral reefs.
There is a special type of algae (called zooxanthellae) that lives inside the coral. The two organisms have a mutual symbiotic relationship. The algae produces oxygen and removes waste for the coral while the coral provides a home and certain substances that the algae needs to photosynthesize.

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Benefit to Humans

Coral reefs benefit humans in many ways. One of the first to come to mind is tourism. Many people make a living by hosting diving or snorkeling tours around coral reefs. They are also a source for biomedical discoveries. For example, scientists have revealed that certain marine snails create a venom that can be used as a painkiller.
Reefs protect coastal areas. They keep the sand from being carried off by currents. Some reefs, such as barrier reefs, grow close to the shoreline. When a large storm moves onto the coast, storm surges, or really big waves, accompany the changing weather. The reefs, if growing in between the storm surges and the coast line, can break the wave, either completely barricading it or lessening its power.


Enemies to Corals

While coral reefs have many enemies, there are four that come to mind: destruction, pollution, over fishing, and bleaching. Corals are sessile and slow growing organisms, meaning they can’t protect themselves from becoming damaged by a boat running aground or a giant anchor dropping on top of them. Once a piece of coral has broken off from the colony, it dies. Pollution can smother corals, preventing the algae from producing oxygen through photosynthesis. Overfishing occurs when fish can’t repopulate at a fast enough rate to keep up with the amount of fish that fishermen take.
Coral bleaching is when either the coral ejects the algae that live with them or the algae dies. Without the algae to make oxygen, the coral suffocates to death. It’s called bleaching because the coral loses color as the algae leave or die.


Coral Bleaching

Coral bleaching occurs when corals become stressed and expel the algae from the tissues they live in, turning the coral white. This bleaching does not kill the coral, but it does put them under more stress and the potential to die. This act of expelling the algae can be caused by many factors. Changes in the seawater could include an increase in temperature or salinity (the salt content). Certain chemicals such as benzophenone-2 (BP-2) can induce stress. Specifically, low concentrations of BP-2 can kill juvenile corals and possibly increase the probability of mutations in the DNA. Diseases are also a cause of stress and bleaching.


What can we do to help?

We can help protect the coral reefs by changing tiny parts of our lives. You can dispose of trash properly, rather than dumping it to the side and letting it make its way to the ocean. When swimming or diving at the reefs, you can use coral reef safe sunscreen that doesn’t contain the harmful chemicals that other sunscreens have. You can also be mindful of where you are swimming and take care to not kick or break coral colonies.

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