Coral reefs

One of the most amazing habitats on earth is found in warm, clear, shallow waters of tropical oceans worldwide. Tiny animals called polyps live in colonies, and when they die their skeletons form a hard, branching structure made of limestone. This is coral – the growing, living structures that provide shelter and food for many marine animals.

Warm tropical waters are home to three different types of coral reefs:
Fringing reefs form along a coastline. They grow in shallow water. Barrier reefs grow parallel to shorelines, but farther out, usually separated from the land by a deep lagoon. They form a barrier between the lagoon and the seas, making travel difficult for ships. Coral atolls are rings of coral that grow on top of old, sunken volcanoes in the ocean. They begin as fringe reefs surrounding a volcanic island; then, as the volcano sinks, the reef continues to grow, and eventually only the reef remains.

Chockful of Life
Groupers, clown fish, and hundreds of other fish species dart in and out of the colorful reefs. Anemones, attached to the coral, sway in the ocean currents. Crustaceans, like shrimp and crabs, scramble about looking for tidbits of food. An occasional sea turtle glides by looking for a quick meal. And inside the coral itself, tiny microscopic organisms called zooxanthellae ( zo-o-an-thel-lay) color the coral and provide it with essential nutrients. They also help the coral secrete limestone and remove wastes. Other organisms such as tube worms and mollusks build up the coral further by leaving their skeletons in the coral when they die.

Hard and Soft Coral
Hard coral is made of the same material as classroom chalk (calcium carbonate). This coral must live in clear, shallow water because the organisms that provide it with nutrients are actually a type of algae that need the sun. Brain coral and elkhorn coral are hard corals. Soft coral, on the other hand, look like colorful plants and graceful trees, and can live deep in the ocean. Coral fingers, red sea whips, and yellow gorgononia sea fans sway softly to and fro as the ocean waters move past them.

Corel Reefs are Sensitive to Change
Coral reefs develop in warm water, usually near land, in the tropics. They are very sensitive and prefer temperatures between 70 and 85 degrees Fahrenheit. Higher temperatures cause the algae living inside the coral polyps to die. Only the skeletons remain, causing the coral to appear white, which scientists refer to as “bleaching.”

In the past few years, because of global warming, an unusual number of bleaching” events have occurred worldwide.

Not only do temperature changes harm the coral reefs, but healthy coral life can be destroyed by sewage, storm water run-off, fertilizer leaching into the ocean, and petroleum in the water. Careless boating, diving, and fishing also break up the coral reefs.

A Slow Grower
Coral reefs grow very, very slowly. Some of the deep-sea coral grow only a centimeter a year. It has taken hundreds of thousands of years for the coral reefs along our coasts to develop. Some of the best-known reefs are the Great Barrier Reef off the NE coast of Australia and reefs off the Florida Keys which stretch almost all the way to Cuba.

Coral Reefs Protect Our Coasts
Coral reefs serve as barriers and protect our coastland from erosion during storms.  As you have seen, they are also a unique habitat for a multitude of sea creatures. And scientists have just started studying the properties of the biological compounds and microbes that exist only in the reefs. Perhaps chemicals in the reef will give us clues to curing diseases or solving some of the earth’s problems.

If the coral reefs are constantly exposed to damage by humans and global warming, the strain will be too much for them, and we, and the wildlife that live amongst them, will lose them permanently.

The reefs protect us and other wildlife. Let’s help protect them. After all, It’s Your Planet Too!