Scleractinia

order of cnidarians Scleractinia (Scleractinia) is an order comprising closely related families of organisms. It contains 26 families with 326 known species. Key family groups include Acroporidae, Agariciidae, Astrangiidae, Astrocoeniidae, Caryophylliidae, and Cladocoridae. Among its members, 81 species are currently classified as threatened (Critically Endangered, Endangered, or Vulnerable). It belongs to Anthozoa (Anthozoa).