By Dustin Price , Nathan Blackmon , Josh Crawford , and Osmond Curtis Coral Reefs By Dustin Price , Nathan Blackmon , Josh Crawford , and Osmond Curtis

What are Coral Reefs ? A mound or ridge of living coral, coral skeletons, and calcium carbonate deposits from other organisms such as calcareous algae, mollusks, and protozoans.  Most coral reefs form in warm, shallow sea waters and rise to or near the surface, generally in the form of a barrier reef , fringing reef , or atoll .Coral reefs grow upward from the sea floor as the polyps of new corals cement themselves to the skeletons of those below and in turn provide support for algae and other organisms whose secretions serve to bind the skeletons together. The resulting structure provides a critical habitat for a wide variety of fish and marine invertebrates.  Coral reefs also protect shores against erosion by causing large waves to break and lose some of their force before reaching land. The Great Barrier Reef off the northeastern coast of Australia extends for some 2,000 km (1,240mi), making it the world's largest coral reef. 

Coral Animals and Organisms Stony , or true , corals ,and sponges , are the primary organisms depositing the massive amounts of calcium carbonate that make up most of the structure of coral reefs . Coralline algae and several other organisms deposit lesser amounts of this mineral . Ex: Hydrozoa called fire coral ,brain coral, bubble coral , Xenia / Anthellia, and hammer corals , goblet sponge, and cloud sponges .

Role of Sponges in Reefs Marine organisms hidden in caves, such as sponges, play an extremely important role in the nutrient cycle of coral reefs.  Sponges filter the water around and in reefs. They take up planktonic particles such as bacteria and excrete inorganic nutrients. In turn, these nutrients can facilitate the growth of marine plants and other organisms.

Formation of Coral Reefs     Coral reefs form in shallow water that is at a nice warm temperature. Coral forms near land and in the tropics. They are very rich in life. Clown fish and many other organisms can be found here. Coral reefs are very tall and can stretch for miles. The coral is formed by polyps, and when they die they leave behind a stony limestone structure. Only the coral that are hard can form coral. It is very vulnerable to death. If it is kicked, even slightly, it will most likely die. Coral can also die by turning white. There are three types of coral: fringing coral, barrier coral, and coral atolls. Fringing coral forms along continental shelves and coast lines. Barrier coral runs parallel to the shorelines and are separated by lagoon. Coral atolls grow on top of old sunken volcanoes. Coral reefs are a very important ecosystem. They contain a lot of rich resources such as new medicines. They are very delicate and even a slight temperature change can stress them. Chemicals kill them and can block the needed sunlight out. Coral reefs are usually found in bright colors such as: orange, tan, yellow, purple, and green.

Atoll Reef

Fringing Reef

Barrier Reef

Animals that live in Reefs Coral Reefs are home to many animals and organisms they also provide a place as to where organisms can find food. A single patch of coral may provide a habitat for 70 to 80 species Ex: Shrimps , lobsters ,crabs ,featherduster worms ,molluscs ,sea cucumbers , stars , sea urchins , and a wide variety of fishes .

Coral Reef Food Web

Coral Reefs in Danger of Being Destroyed All of the tropical coral reefs in the world will be disintegrating by the end of the century because of the rising acidity of the oceans caused by a build-up of man-made carbon dioxide in the atmosphere, a study has found. Coral reefs start to disintegrate when the acidity of the oceans rises beyond a certain threshold, and this point is likely to be reached before 2100, said Jacob Silverman of the Carnegie Institution of Science in Washington. Carbon dioxide in the air dissolves in the sea to form carbonic acid, which interferes with the ability of coral organisms to make their calcium carbonate shells which form coral reefs. But once the shells stop forming, the reef quickly crumbles.

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