HOW IT WORKS
With the right conditions, some coral species can be induced to spawn in the lab.
1 Reef-building Acropora coral can be induced to spawn in tanks. They release bundles of sperm and eggs, which float to the surface of the water.
2 Each bundle contains around 10 eggs and thousands of sperm.
3 Spawning can be predicted and lasts for just 15 minutes. The bundles are scooped out of the water in a cup.
4 The mixture is stirred and the bundles break apart. The lipid-rich eggs float on the surface, whilst the sperm sink, swim and turn the water milky.
6 The sex cells from one colony (black cups) are mixed with those from an unrelated, genetically distinct colony (blue cups).
6 Once the eggs are fertilised, the cells will start dividing to create an embryo. Each embryo will eventually become a larva called a planula.
7 Planulae are transferred into a settlement tank. They sink and attach to specially prepared tiles where they begin to grow into coral polyps with mouths and tentacles. A few weeks later, zooxanthellae are added to the tank, which the corals incorporate into their cells.