These organisms form symbiotic associations with zooxanthellae.
These organisms are divided into brooders and broadcasters, based on how they spawn planulae. Some of these organisms that produce gorgonin are being researched for use as bone implants, in part due to their trabecular structure. In recent years, frequent Acanthaster outbreaks have caused sharp declines in their populations. These organisms form symbiotic associations with zooxanthellae. When they are stressed, they eject those (*) algae, leading to bleaching. Growth rings in the aragonite skeletons of Scleractinia, one order of these animals, provided the first examples of the biological effects of ocean acidification. Â They are classified based on whether their symmetry is 6-fold or 8-fold, and they lack a medusa stage. For 10 points, name these cnidarians that build reefs.
These organisms are divided into brooders and broadcasters, based on how they spawn planulae.
corals [prompt on "Anthozoa" or "sea anemones" because sea anemones aren't well-distinguished from corals; prompt on "Cnidaria"]