Corallivore

Corallivores are an important group of reef organism because they can influence coral abundance, distribution, and community structure.

The first recorded evidence of corallivory was presented by Charles Darwin in 1842 during his voyage on HMS Beagle in which he found coral in the stomach of two Scarus parrotfish.

[1] Darwin dissected several parrotfish and found pieces of coral and finely ground calcareous material in their stomach.

[1] In 1952, the first descriptions of organisms actively consuming coral were written by Jacques Cousteau and published in National Geographic.

[2][3] During his trip to the Red Sea aboard RV Calypso, Cousteau swam with a pair of green humphead parrotfish and watched them take regular bites and leaving white scars on the coral around them.

[3] Like Darwin, Cousteau also noticed the sediment particles that were produced in the parrotfishs' waste and settled to the seafloor.

[3] Cousteau noted the leisurely speed with which the parrotfish consumed the coral and remarked that they appeared "unhurried" and like "sea cows, browsing on stone pastures.

[5] Facultative corallivores are defined as organisms that regularly consume coral without it comprising a large percentage of their diet.

[5] Additionally, studies suggest that the damage from excavating takes significantly longer to heal than other types of corallivory.

[13] In addition to the cutting edge adaptation, parrotfish also have well-developed crossed joints that connect the dentary and articular bones of the lower jaw, which presents a mechanical advantage that makes the bite much stronger.

[2] It is estimated that one crown-of-thorns star may eat up to 6 square meters (65 sq ft) of live coral per year.

[2] The genus Drupella are obligate corallivorous sea snails that specialize on fast growing Acropora and Montipora species.

Corals with populations of the mucus feeding Tetralia and Trapezia crabs were shown to have a greater chance of survival during an crown-of-thorns star outbreak.

[2] Trapezia crabs are known to symbiotically benefit their host coral by cleaning sediment and debris off their surface.

The nudibranch, Phestilla sibogae, has been known to incorporate zooxanthellae, a phytoplankton symbiont, harvested through corallivory into its cerata.

[16] Corals divert energy and resources towards repairing damage, which has shown to suppress additional growth.

If the species of coral being consumed is spatially dominant, grazing can help control growth and promote greater reef diversity.

[5] In particular, obligate corallivores have been reported to experience high population declines following instances of coral loss.