a preference for one or a few types of coral. However, the obligate corallivore snail, Coralliophila abbreviata, is known to feed on 26 different species of coral and shows no distinct preference for one species. C. abbreviata lacks a radula that would allow it to scrape off coral tissue, so coral is broken down by digestive enzymes. Not all corallivores are detrimental to coral health. 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. Trapezia crabs are known to symbiotically benefit their host coral by cleaning sediment and debris off their surface. Some organisms receive more than nutrition. The nudibranch, Phestilla sibogae, has been known to incorporate zooxanthellae, a phytoplankton symbiont, harvested through corallivory into its cerata. After they are incorporated, the zooxanthellae continue to photosynthesize and provide energy for the nudibranch. Impacts on ecosystem Corallivory often results in damage to coral or loss of coral biomass, and sometime directly causes coral death. Corals divert energy and resources towards repairing damage, which has shown to suppress additional growth. The ability for a coral to repair itself is partially based on the size of the lesion; since not all damage can be healed, superfluous damage can result in permanent change to the reef. Corals have shown to energetically prioritize repairing damage over reproducing, so corallivory can have a negative effect on coral reproduction. Additionally, studies have shown that grazing by corallivores can be associated with reduced zooxanthellae densities. Scientists believe that excessive fishing of predators to corallivores, like large piscivorous fish, may result in an increase in corallivore abundance. This increase in corallivory may have a future negative effect on coral health and density. Corallivory can indirectly cause an increase in growth of competitive organisms, such as algae and sponges. Additionally, some corallivores have been implicated in the spread of coral diseases. Some studies have shown that corallivores can have an influence on the competitive abilities of coral colonies. Corallivory is not always detrimental to coral reefs. If the species of coral being consumed is spatially dominant, grazing can help control growth and promote greater reef diversity. Corallivores are often sensitive to declines in coral health and population size, and are negatively affected during periods of high coral loss. In particular, obligate corallivores have been reported to experience high population declines following instances of coral