Soup of Egg and Sperm

May 12, 2021

Bad luck can run out. Hantu Blog volunteer Nicholas Chew didn’t give up on his quest to witness the mass spawning of corals in Singapore during a night dive. His tenacity finally paid off with an opportunity to participate in one of Earth’s spectacles of Nature!

By Nicholas Chew: I tried once in early April, but did not manage to witness the mass coral spawning as there wasn’t much activity then. This was my second try, and this time we got really lucky with an explosion of mass spawning activity!

From the subdued spawning the previous month, predictions were that the main spawning event would be a month late this year. This time, I was quite focused on looking for spawning corals instead of getting distracted by other reef critters. This is actually very hard for me to do as there are so many amazing subjects to photograph at Pulau Satumu! It was another chance to witness one of the ocean’s natural spectacles and I was determined to not miss it.

This time, we had two boats heading out at the same time. This meant more eyes on the reef to look for spawning activity, and even greater chances to see it! If anybody saw any activity, he/she could alert everybody else.

What a magical time swimming through a soup of eggs and sperm. It was a bit like snowing but upside down.

Nicholas Chew

From about 8.30pm onwards, we were all gathered at the reef crest and shallower, as these shallow corals are always the most likely to spawn. Everybody was really paying close attention to the corals, especially the ones which had already “set” – Eggs visible just under the surface of the corals, like many ripe pimples ready to pop! These were mainly massive corals from the genus Platygyra.

By about 9pm, there were a few stray pink eggs in the water column, which I did use to try and figure out where the spawning corals were. After a few failed attempts, more and more eggs were seen, and it wasn’t very hard by then to catch a spawning coral colony in action. It was perfectly synchronised, a beautiful and magical scene. For about half an hour, an almost continuous steam of egg and sperm bundles were released from many corals at once. Very quickly, the water was thick with sperm and eggs. It was like swimming through snow but the snow went upwards instead of down!

I’m very thrilled to have finally witnessed mass coral spawning after years of failed tries. It’s so easy to miss it as it happens so rarely and in the dead of night. I feel very privileged to have experienced it firsthand, and at such a nice reef. It was a mini nat-geo scene right in our own backyard! 

This experience was exactly as I had expected – a special dive which I will always remember.

I learn a little more about corals each time I take part in these spawning dives, and I hope to see and photograph even more types of corals spawn in future attempts!

Posted in Biology, Volunteers