The wonder that is mass synchronised coral spawning

The Great Barrier Reef is always a source of inspiration and information for our school science incursions.

One of the most spectacular events to occur on the Great Barrier Reef is the annual synchronised spawning of corals. This mass reproduction only happens once a year and involves different species of coral simultaneously releasing tiny egg and sperm bundles into the water.

By expelling the eggs and sperm at the same time, the coral increases the likelihood that fertilisation will take place. The mass spawning occurs after a full moon and only after rising water temperatures have stimulated the maturation of the gametes.

The spawning lasts between a few days and a week. The phenomenon- which only happens at night- resembles an underwater snowstorm. But rather than being all white, there are also clouds of red, yellow and orange. All the bundles rise slowly to the surface where the process of fertilisation begins.

While spawning takes place on a large scale, it doesn’t happen across the entire Reef all at once.

Instead, the time of year that corals spawn, depends on their location. Those on inshore reefs usually start spawning one to six nights after the first full moon in October, whereas those in outer reefs spawn during November or December.

Scientific exploration has revealed so much about this amazing phenomenon but there is still a lot we are yet to discover.

In our school science incursions, we bring the science curriculum alive and encourage students to think scientifically about the amazing marine world around us. They are also invited to be part of the conversation of how we must protect this great natural treasure.