Young Coral Polyps Can Seriously Get Down With Themselves

If you’re a non-mature coral polyp living out your young experimental years in the Great Barrier Reef, chances are you’re spending your non-calcified life period trying out different zooxanthellae partners, waiting until you can release eggs into the warm reef currents. Or now, as scientists at the Australian Institute of Marine Science have discovered, you’re making clones of yourself.

Coral polyps generally reproduce via sexual reproduction, releasing eggs and sperm into surrounding water to produce fertilized offspring that are then carried to different locations by ocean currents. Coral embryos, however, differ from other members of the animal kingdom in the sense that their embryonic sacs lack any sort of protective membrane, leaving them quite vulnerable to the often turbulent ocean surroundings.

This could be a potentially massive problem for the tiny polyps, but recent research sheds a light on the phenomena showing that leaving embryos open to breaking apart is actually part of nature’s plan, and helps fortify coral’s adaptations for species survival. Mature coral polyps (the already calcified ones in the structures we think of as “coral”) generally release eggs for fertilization on stormy nights where waves and currents are stronger and more able to disperse the polyps. The fact that the tiny fertilized embryos may break apart from current allows each cell to disperse and essentially create a clone of the tiny embryo.

Until now, scientists had no idea that coral was able to produce asexually reproduced copies of itself, since they were known to be a sexually reproductive species.

Dr Andrew Heyward, one of the researchers involved with the project, told Science that it was a surprise to them that pieces of broken embryos were still able to settle and grow like any other fully formed polyp embryo.

“Much like humans, it’s important that the offspring of corals have genetically distinct parents, but these embryos also readily clone to form multiple versions of themselves, and helps to explain how coral maximise their chances of finding a suitable habitat in which to settle and survive.”

It’s a small factor in the survival of coral, which becomes increasingly endangered by the hour due to factors such as warming water temperatures which kill off its symbiotic algae partners, zooxanthellae, and fertilizer runoffs from tributaries around the world which cause harmful algae blooms in reef areas. However if this research is viable, it means coral polyps are one of the only species in the world capable of both sexual and asexual reproduction. Well, other than awkward teenage boys.