Coral - Canvas

Corals are animals related to jellyfish and anemones. Solitary and colonial corals catch plankton and suspended food particles with arm-like tentacles, which feed a centrally located mouth. Coral reefs are formed by huge colonies of corals that secrete hard calcareous (aragonite) exoskeletons that give them structural rigidity. These colonial "hard corals" may form elaborate finger-shaped, branching, or mound-shaped structures, and can create masses of limestone that stretch for tens or even hundreds of miles.

Most hard corals also host symbiotic algae, a long-standing and successful partnership. These algae provide them with an additional food source through photosynthesis.

When corals are stressed, they expel these algal symbionts through a process known as coral bleaching. Corals also face serious risk of diseases; black band, white band, and yellow band diseases have been reported from many localities. Hawaiian corals, however, have been relatively free from disease, but the first case of black band disease was reported in 1994.