Intro to Coral Spawning


There is no doubt that coral is a unique and fascinating marine animal—yes, we said animal. Coral are actually a colony of animals that have banded together, creating the plethora of shapes and colors that are the landscape for our dives. But you know all this already, don’t you? What you’re here to learn about is how these animals reproduce to bring more coral into the world, which, as we know, is something the planet desperately needs. So let’s start our journey to discover the fascinating phenomenon that is coral spawning.

What is coral spawning?

You already know all about coral because you’ve read about it in our What Are Coral Reefs? blog. So let’s jump right in and explore what exactly coral spawning is. Coral spawning is the reproductive process of coral. It is a simultaneous release of coral gametes (sperm and eggs) in little bundles in search of pairing up with another bundle of the same species. When that happens, they then develop into coral larvae (planula), and float along the surface of the sea for a little while. When the time comes, they drop back towards the ocean floor guided by chemical and light sensors on its back, making a home within the reef. If it’s lucky, it will land in an appropriate space where it can officially morph into a polyp, clone itself, and grow and thrive, perpetuating the cycle of coral life.

The Importance of Coral Spawning

Coral has been on a significant decline for decades, so coral reproduction is essential to the ocean’s sustainability. Therefore, given the small percentage of potential survival of these larvae due to the specifics around timing and where it lands and what it runs into, coral spawning is a very big deal in order to keep the coral population thriving.

When Does Coral Spawning Occur?

One thing to understand is that there are more than 6,000 different species of coral. Of that, about 1,500 different species of stony coral (the kind that participate in broadcast spawning). That being said, we can’t expect them all to work on the exact same rhythm on the exact same night—talk about a logistics nightmare! Because remember, the gametes need to meet up with gametes of the same species for this thing to work. But they do like to plan around similar timing to one another. 

Per coral species, coral spawning tends to be an annual event and follows a summer full moon—the August full moon for the Northern Hemisphere, and December-January for the Southern Hemisphere. About 7-10 days after the full moon, coral all over the world will begin the spawning process, starting sometime in the nighttime.

How to Witness Coral Spawning

For those of us in or around Florida, if you’re hoping to catch a glimpse of this spectacular event, book a summertime night diving trip some days after the full moon to the Florida Keys. The good news is that even if you miss the original spawning moment, the spawning event itself can take anywhere from a half an hour to a few days to a whole week!

*Remember to respect marine life and coral reefs by avoiding touching or disturbing them. Stay flexible with your plans, as nature can be unpredictable. With proper planning and consideration, you can have an unforgettable experience witnessing coral spawning in the beautiful waters of the Florida Keys.


When does coral spawning occur?

Coral spawning occurs each year in the dark waters of the night. This happens a week or so after a summer full moon (usually in August in the Northern Hemisphere) when the waters are warm and ideal for the process. 

How long does coral spawning last?

Once it gets going, coral spawning can last anywhere from half an hour to a week. 

What does coral spawning look like?

Many have said that coral spawning looks similar to an underwater blizzard, surrounded by a myriad of colorful dots all around. Think of being inside a snow globe!

What triggers coral spawning?

The lunar cycle, water temperatures, tide, and length of the day let coral know that conditions are just right for a spawning event.

Where can I see coral spawning?

Wherever there are hard or stony coral! You’ll have a greater chance of getting a spectacle of an event when around larger coral reefs like in the Florida Keys.