Translations:Adventist Youth Honors Answer Book/Nature/Marine Invertebrates/25/en

s. Coral

• 

  Montastrea cavernosa
  (Cavernous Star Coral )
• 

  Balanophyllia elegans
  (Orange cup coral)
• 

  Trachyphyllia geoffroyi
  (Brain Coral)

Corals are skeletal remains of marine organisms from the class Anthozoa and exist as small sea anemone–like polyps, typically in colonies of many identical individuals. The group includes the important reef builders that are found in tropical oceans, which secrete calcium carbonate to form a hard skeleton.Over thousands of generations, the polyps lay down a skeleton that is characteristic of their species. A head of coral grows by asexual reproduction of the individual polyps. Corals also breed sexually by spawning, with corals of the same species releasing gametes simultaneously over a period of one to several nights around a full moon.Although corals can catch plankton using stinging cells on their tentacles, these animals obtain most of their nutrients from symbiotic unicellular algae called zooxanthellae. Consequently, most corals depend on sunlight and grow in clear and shallow water, typically at depths shallower than 60 m (200 ft).