Reefs in the Florida Keys, for example, hold at least 45 species of stony coral, 37 species of octocoral, five species of sea turtles, 500 species of fish, about 1,700 species of mollusks and hundreds of species of sponges. Coral reefs protect coastlines from storms and provide billions of dollars of food and jobs every year to people around the world. Corals are ancient animals related to jellyfish and anemones. An individual coral is known as a polyp, a very small and simple organism consisting mostly of a stomach topped by a tentacle-bearing mouth. The polyps extend their tentacles at night to sting and ingest tiny organisms called plankton and other small creatures. Coral reefs are found all around the world in tropical and subtropical oceans. They are usually found in shallow areas at a depth of less than 150 feet. However, some coral reefs extend even deeper, up to about 450 feet deep. Despite how important coral reefs are to life in the ocean, all of them in the world add up to less than one percent of the sea floor.