Coral spawning: Great Barrier Reef is ringed by baby corals

Written by By Katelyn McCabe, CNN

The world’s largest coral reef system, Australia’s Great Barrier Reef, has once again staged a spectacular spawning event during the past week.

On Saturday, an estimated 35,000 coral polyps — tiny animals that secrete the cell walls of many marine organisms — were hatched into six.5-inch-tall cones, thanks to heavy rains and warm water temperatures.

An estimated 35,000 corals hatched at the 2015 Great Barrier Reef. Credit: Courtesy Florey Institute of Technology

Experts at the Coral Reef Studies Program at the Florey Institute of Technology in Queensland say the event (known as “Stormwater Harvest”) occurs once every 10 years. “It’s essentially a massive ‘pancake’ laying (and) growing” the cones, according to Dr. Hincks, who leads the National Science Program for the Great Barrier Reef.

It is the second time in three years that the northeast tropical region has seen the event, which is annually documented by remote cameras and vessels in the region. The Great Barrier Reef itself has been mostly closed to public recreation since 2013, after the BP oil spill.

The coral animals will spend their lifetime holding on to their tiny, snow-white cones before being eaten by larger animals. They will then lay eggs, which in turn will feed on the cones.

Dr. Helen Liddington explains: “The next in turn will deposit their eggs and larvae in the cone for the next generation of corals. After laying down their seeds, the stones in the cones do a little bit of internal decomposition and release the corals from the wave (of) prey, and the next generation is formed.”

Female coral eggs can grow up to six-feet in length. Credit: Courtesy Florey Institute of Technology

In the past, tourists have been able to visit the area where some of the spawning takes place. The Great Barrier Reef is one of seven World Heritage Sites in Australia. The UNESCO Educational Society described the reef as a “living icon” in 2015.

One witness to this year’s event told National Geographic, “It’s like something from the movies. The clouds throw a whole rainbow over the water, which adds to the magical feeling, and the rain sweeping across the ocean creates massive waves that can be seen from space.”

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