Branching Corals. M.L. Anderson, 2009. Corals. Corals can be considered either hard or soft depending on their consistency and the nature of their skeletons. Hard corals are reef building corals that secrete a hard external limestone skeleton.
Coral reefs offer:
Elkhorn Coral grows upwards to get closer to the sun.
Bleached elkhorn coral near St. Croix, USVI, in October 2005. (Source: NOAA Center for Coastal Monitoring and Assessment)
Corals begin to starve once they become bleached. If conditions return to normal, corals can regain their zooxanthellae, return to normal color and survive. This stress, however, is likely to cause decreased coral growth and reproduction, and increased susceptibility to disease.