14/10/2026
Coral spawning is one of the strangest and most beautiful events happening on our planet, and it's a reminder that corals are not plants or rocks. They're animals, with reproductive strategies as surprising as anything else in nature.
Most reef-building corals are broadcast spawners. Instead of reproducing individually, they release eggs and s***m into the water column, where fertilisation happens externally. What makes it extraordinary is that they do this in near-perfect synchrony. Across entire reefs – and sometimes across hundreds of kilometres of coastline – colonies of the same species release their gametes within minutes of each other, often on the same night of the year.
The timing is driven by a combination of cues: water temperature, day length, tidal patterns, and crucially, the lunar cycle. Many species spawn a few nights after a full moon, when conditions are statistically most likely to maximise fertilisation and survival of the next generation. How corals detect the moon isn't fully understood, but research suggests they have light-sensitive proteins that respond to lunar brightness.
When it happens, it looks like an underwater snowstorm in reverse, with clouds of pink, orange, and white eggs floating upward through the water column. Divers who've witnessed it describe it as one of the most surreal things they've ever seen.
It's also fragile. Spawning events depend on specific environmental conditions, and climate change, pollution, and sediment are all disrupting them. Some reefs that once spawned reliably every year are now spawning less successfully, or not at all. But where it still happens, it's extraordinary.
