While even astronauts can see the structures made by the coral animals from space, not everyone is aware of the real marvel of the reef, algae. Inside the gut of many coral polyps are microscopic algae commonly called zooxanthellae (Symbiodinium spp.). These algae are photosynthetic, making food from sunlight which is also used to feed the coral. In fact, for some species of coral up to 95% of the corals daily requirement can come from the algae. Coral bleaching occurs when the algae is expelled from the coral host, which leaves it with a ghostly white color as if someone had poured Clorox all over it, hence the term bleached.
|Bleached coral on a wreck, 2011. Photo credit: Me|