Corals reproduce through a mechanism known as coral spawning. In coral spawning, all of the corals from one species will release their eggs and sperm into the water over about 15 minutes, which rise to the water’s surface and are fertilized. This event, which usually happens just once a year for most corals, is one of the most amazing and miraculous events in all of nature.
Not only is it amazing that corals can all time this event without having a brain or any means of communication, but this is also where the next generation of corals will come from.
Each coral larvae that settles successfully is called a coral recruit, and is a genetically distinct individual. These recruits replenish the reefs with new individuals, and increase the reefs diversity and ability to adapt to changes.