Nowadays we often associate the word “twilight” with “vampires”. Try searching the first word in Google and at the top of the list is The Twilight Saga: Breaking Dawn Part 2. In this context though, we are not going to talk about the epic book (or movie) but about something that is also related to twilight – coral spawning.
The synchronized mass spawning of corals occurs annually, particularly only at twilight during a full moon. It is characterized by millions of minute particles being released into the water column, floating freely along the current, and forming a slick that extends meters wide and kilometers long and where fertilization takes place . Factors that trigger this event are, viz.: chromatic changes based on the lunar cycle; temperature; and, day length . Overlapping spawning times happen among species of corals. This was first documented in the
Great Barrier Reef in 1981. And thus to achieve maximum fertilization success, as the law of nature
dictates, different species respond similarly but independently to timing cues
set by the factors said above . Their spawning behavior may be analogous to pollination of plants but
remember: corals are animals, not plants.
To learn more about the behavior of corals, visit SeaLifeBase.
“If your ship doesn’t come in, swim out to meet it!” – Jonathan Winters
 Thomas, A. 2002. Hard core spawn. ABS Science.
 Sweeney, A.M.,
Boch, S. Johnsen, and D.E. Morse. 2011. Twilight spectral dynamics and the
coral reef invertebrate spawning response. Journal of Experimental Biology
 Guest, J. 2008. How reefs respond to mass coral spawning. Science 320:621-623.