Corals climax despite doomsday messages the reefs dead
Love makes the world go round, it also makes wildlife go absolute crazy, people included. It’s a basic seeded instinct. It’s why we’re here. The result is ingenious ways that animals have increased their chances of reproducing or what we like to call doing the ‘no pants dance’. Enter the humble reef building coral, the glamazon of tropical reefs all around the world.
We know these animals can build the largest living structure, which can be seen from space… the Great Barrier Reef. It’s an impressive feat for an animal no bigger than a thumbnail. But when it comes to love, what the corals can’t do is move. They’re stuck to the spot, which doesn’t seem to leave many possibilities for finding a mate on a Saturday night.
What’s their solution? Corals cleverly co-ordinate the release of their packages of ‘sex cells’ at the same time. Scientists at James Cook University first discovered this natural phenomenon in the early 1980’s. It happens only on one night of the year for each species, so precision timing is everything. The moon becomes their sexual timepiece, providing the cue for the mass release of eggs and sperm into the water column.
The result? 2-7 days after the full moon corals release their eggs and sperm into the water, in what scientists have dubbed ‘the world’s largest synchronized climax’. It’s safe group sex at a distance without the nasty complications and STD’s.
This increases the chance of fertilization. Releasing their eggs and sperm at night also makes it more difficult for predators to see, and what predators can see them are simply overwhelmed and unable to devour such a mass of food, allowing most of the sex cells to survive.
We were lucky enough to witness this maritime orgy at Moore Reef, off the southern coast of Cairns in the northern section of the Great Barrier Reef a couple of weeks ago. It was a magical sight as billions of coral polyps broadcasted their eggs and sperm into the water, rising to the surface like a silent sexual symphony.
It begs the question… if you’ve got billions of different species of eggs and sperm swimming around at the same time, how do they know who is who and who they should do? Scientists have discovered that the eggs contain a chemical substance or ‘sperm attractant’ that is irresistible to the sperm of the same species, while a pseudo chastity belt or membrane keeps other eager sperm at bay.
What happens next? The sperm penetrates the egg and within a few hours it develops into a swimming larva where it rides the currents. If it’s not eaten by the plankton feeders, jellyfish and other filter-feeders it will settles on a hard surface and metamorphosise into a single coral polyp to begin a new coral colony.
Unfortunately no spawning events were recorded in far northern sections, which have been heavily hit by bleaching. But there is hope and we saw it first hand. Hopefully this spawning event that we witnessed can help recolonized the northern counterparts and help with the reef recovery efforts.
So people of the world…we proudly proclaim that romance on the reef isn’t dead and our love affair with it shouldn’t be either. So get it on the action and ‘sea for yourself’. Admittedly you may have to wait another year, but trust us; it’s a climax worth waiting for.
Credit: Big thanks to the Biopixel Crew for the trip out to the reef and for scaring the living daylights out of our resident mermaid (she is still in a padded room rocking back and forth..) and Sunlover for letting us use their pontoon. Footage: Oceans IQ
