World Largest Coral Reef!

GREAT BARRIER REEF - WORLD'S LARGEST CORAL REEF SYSTEM

it is the worlds largest coral reef system, composed of roughly 3000 individual reefs & 900 islands stretching for 2600 km over an area of approximately 3,44,400 square kilometers. the reef is located in the coral sea, off the coast of Queensland in northeast australia. Great Barrier Reed can be seen from outer space & is worlds biggest single structure made by living organism. this is build by billions of tiny organisms , known as coral polyps. when coral sea basin was formed, coral reef began to grow in the basin until about 25 million years ago, they can increase in diameter from 1-2 cms per year & grow vertically any where from 1-15 cms per year. they are limited to growing above a depth of 150 meters due to their need for sunlight & cannot grow above sea level. the land formed the subtrate of the current great barrier reef was a coastal plain formed from the eroded sediments of the great dividing range with some larger hills from 20,000 years ago until 60,000 years ago, the sea level rose steadily. by around 13,000 years ago the sea level was 60 meters lower than the present day, corals began to grow around the hills of the costal plain , which were by then, continental islands. this GBR supports a diversity of life, including many vulnerable & endangered species, some of them are endamic to the reef system. there are thirty species of whales, dolphines , porpoises have been recorded in the GBR, including the dwarf minke whale, indo-pacific humpback dolphin & the humpback whale. large populations of dugongs live there. six species of a sea turtles come to the reef to breed-the green sea tutle, leather back the sea turtle, hawksbill turtle, loggeshead sea turtle, olive ridly. salt water crocodiles live near the reef.