You Are At: AllSands Home > Science > Coral reef ecosystems
Pirates used to hide their treasures in sheltered coves in coral reefs. Now, anyone with a scuba tank or snorkel can find strange and beautiful treasures in the coral reef itself.

Many mounds of beautiful colors sit at the bottom of the seas. These mounds are actually millions of tiny creatures called coral polyps that live upon the skeletons of dead coral.

Some coral lives near the surface, such as staghorn coral. They have branches that catch sunlight from every angle.

Some coral live deeper, like plate coral. They have branches like satellite dishes that spread out to catch sunlight.

Over 80 million square miles of the Earth are covered by coral reefs. That is more than 25 times the size of the United States. They live in an area 3000 miles wide that encircles the Equator, 30 degrees north and 30 degrees south of it. The largest coral reef is the Great Barrier Reef off the eastern coast of Australia. It stretches for 1250 miles. Some coral reefs are thousands of feet thick.

There are four major types of reefs.
1. The fringing reef grows on rocks along a shore.
2. A sandy lagoon separates the barrier reef from land.
3. An atoll is an irregularly shaped ring of coral with a lagoon in the middle. Atolls usually form on top of submerged volcanoes. They are mostly found in deep water in the Indian and Pacific Oceans.
4. The patch reef is located in some shallow, tropical waters. They are small and isolated.

There are two types of coral, soft and hard. Soft coral has flexible skeletons that can sway in strong currents. Sea whips and sea fans are examples of soft coral. Hard coral is just the opposite. The skeleton is hard and stony. Some examples of hard coral are pillar, cabbage, brain, plate, and bubble coral.

Coral reef zones are home to one quarter of all marine plants and animals. Nearly a million species of fish, crabs, eels, mollusks, sponges, worms, grasses, algae, and other marine animals live on reefs and use them as nurseries to protect their young. Corals also provide natural filtration of seawater for their neighbors. The reef ecosystems support vast fishers that people, especially coastal nations, depend upon for their protein. Collapse of this ecosystem could mean famine.

Some inhabitants of coral reefs are the dugong (sea mammal), seahorse, moray eel, octopus, sea turtle, crown-of-thorn starfish, giant clam, parrotfish, clownfish, lionfish, and scorpionfish.

Coral reefs are truly one of the most beautiful biomes. Future generations may not have the opportunity to see them. Coral reefs around the world are being damaged and destroyed at an increased rate. Humans have been destroying them by overfishing them. Fishermen dynamite the reef and collect stunned fish that float to the surface. People poison the animals to make it easier to see them. Divers kill the reefs by stepping on them, touching them, and taking pieces from them. Oil from diver’s hands and suntan lotions can kill the coral polyps. Other problems that are hurting the reefs are cyanide fishing, sewage, farm runoff, oil and industrial pollution, tourism, sedimentation, and coral mining.

The reefs and animals living in and around them must be protected. Marine biologists who monitor reefs say that 10 percent of them are already destroyed, and 70 percent could be gone in just 40 years from now unless we change our ways. Can you imagine something that’s existed in beauty since the time of the dinosaurs being destroyed in 40 years?