India, Nov. 3 -- It is a spectacle that takes place just once a year, typically between spring and summer. On a few nights following the full moon, when water temperatures are just right, coral polyps engage in a synchronised mass spawning. Millions of tiny eggs and sperms, bundled together, are released into the water in a coordinated nocturnal event. These bundles rise to the surface under the cover of darkness in what resembles a nuptial dance. To reproduce, each bundle must meet and merge with another from the same species. By spawning en masse, corals increase their chances of successful fertilisation. The result is a planula larva that eventually settles on the seabed to begin forming a new colony.

At this precise moment, scientist...