Although many people mistake corals and anemones as plants, they are actually animals called Anthozoa, which in turn belong to a larger group of animals called cnidarians that carry a sting in their tentacles.
The basic unit of the adult is the polyp; this consists of a cylindrical column topped by a disc with a central mouth surrounded by tentacles.
Colonies of coral polyps are formed by the budding of new polyps from an original, founding individual to create extensive coral reefs.
There are many hundreds of different coral species living in the shallow waters around all of the Koh Lanta dive sites, creating extensive coral reefs and sanctuaries for millions of reef fish.
Anthozoans are carnivores, catching prey with their tentacles. Many species supplement their energy needs by making use of photosynthetic single-celled algae that live within their tissues.
The two main subclasses of Anthozoa are the Hexacorallia (6 sided) and includes the 837 known species of living stony corals, sea anemones, tube anemones and zoanthids. Octocorallia (8 sided) include the soft corals and gorgonians (sea pens, sea fans and sea whips), and sea pansies.