Countdown to 2013: December 30

Coral Reef - Coral reefs are typically found at a depth less than 150 feet so that they are reachable by sunlight. - Corals contain microscopic algae called zooxanthellae that provide the coral with food and give them their vibrant colors - Coral grows on average about 1 mm to 4cm per year. - Coral reefs cover less than 0.2% of our oceans but they contain 25% of the world's marine fish species!