What is the Great Barrier Reef?

About Great Barrier Reef:

• It is a complex of coral reefs, shoals, and islets in the Pacific Ocean.
• It is located off the northeastern coast of Australia in the Coral Sea.
• It is the longest and largest reef complex in the world. It is the largest living structure on Earth.
• It extends in roughly a northwest-southeast direction for more than 2,300 km, at an offshore distance ranging from 16 to 160 km, and its width ranges from 60 to 250 km. 
• It has an area of some 350,000 square km.
• The reef, which is large enough to be visible from space, is made up of nearly 3,000 individual reefs and over 900 islands.
• UNESCO declared the Great Barrier Reef a World Heritage Site in 1981.
• Much of the Great Barrier Reef is a marine protected area, managed by the Great Barrier Reef Marine Park Authority of Australia.
• Biodiversity:
  • It is estimated that the reef is home to around 2000 species of fish and around 600 different coral species.
  • It is home to 4,000 mollusk species and over 250 different shrimp species.
  • The reef is also home to six of the seven known species of sea turtles, more than a dozen sea snakes, and nearly two dozen species of birds.

Q1: What are Corals? 

Corals are essentially animals, which are sessile, meaning they permanently attach themselves to the ocean floor. Corals share a symbiotic relationship with single-celled algae called zooxanthellae. The algae provide the coral with food and nutrients, which they make through photosynthesis, using the sun’s light. They use their tiny tentacle-like hands to catch food from the water and sweep into their mouth. Each individual coral animal is known as a polyp and it lives in groups of hundreds to thousands of genetically identical polyps that form a ‘colony’. Corals are largely classified as either hard coral or soft coral. It is the hard corals that are the architects of coral reefs — complex three-dimensional structures built up over thousands of years. Hard corals have stony skeletons made out of limestone that are produced by coral polyps. When polyps die, their skeletons are left behind and used as foundations for new polyps.

Source: Ocean temperatures in Australia’s Great Barrier Reef now the hottest in 400 years: What a new study says