Coral

There are 2 main classifications for corals: 1. Hard coral (scleractinian and stony coral) which form reefs by a calcium carbonate base, with polyps with 6 stiff tentacles, and 2. Soft coral (Alcyonacea and ahermatypic coral) which are bendable and formed by a colony of polyps with 8 feather like tentacles. Coral colors range from green, brown, pink, yellow, red, purple or blue; the exact color will depend on the exact mix of the zooxanthellae algae present within their tissues, some corals are even known to be fluorescent; these amazing color patterns are due to the incredible concentrations of algae in the coral, with several million algae present per square centimeter of coral.Coral reefs protect coastlines from storms and erosion, provide jobs for local communities, and offer opportunities for recreation. They are also are a source of food and new medicines. Over half a billion people depend on reefs for food, income, and protection.