Anthozoa: Life History and Ecology
Anthozoans, unlike other cnidarians, completely lack a medusa stage; they live exclusively as polyps. While anthozoans retain their nematocysts, or stinging cells, and may feed on large prey or particulate food, a number of anthozoans supplement their diet by growing symbiotic algae in their tissues. Hermatypic, or reef-building, scleractinian corals in particular owe their success to the fact that most have symbiotic dinoflagellate algae in the genus Symbiodinium living inside their tissues. Coral polyps also use their tentacles and nematocysts to feed, but Symbiodinium may actually produce most of a coral's food. For this reason, reef-building corals are exclusively shallow-water dwellers; without light they cannot survive (although solitary corals, octocorals, and anemones may inhabit much cooler and deeper waters). Therefore, one result of global warming and rising sea levels will be the death of coral reefs.
In the photo above, former UCMP graduate student Chris Meyer, SCUBA dives near a coral head somewhere in the south Pacific.
Aquarist Steve Tyree maintains an archive of pictures of living corals and gorgonians, including pictures of eggs and larvae.
SeaWorld/Busch Gardens maintain the Animal Information Data Base, which includes information on corals and coral reefs.