phylum cnidaria or coelenterata jellyfish, anemones, corals
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The Basics
Two tissue layers - an outer epidermis and an inner gastroderm
Nerve net with stinging capsules called nematocysts
Radial symmetry with 2 body types - a polyp and/or medusa
The coral animal may live as a free-floating polyp or build colonies into reefs. Not all corals build reefs.
Stony Coral
Hermatypic or reef buildersPolyp grows in 6 parts to form a body of
calcium carbonateBrain coral and staghorn coral
Soft CoralPolyps with 8
tentacles While part of the reef,
they do not build reefs because their bodies are a soft keratin.
Sea fans and gorgonians
Hydrocoral
False corals resemble the anemonecontain powerful nematocysts that cause
skin irritationFire coral
It has a gas filled float and individuals that function like specialized organs. Some are carnivores with digestion in food vacuoles.
Hydrozoans - Class Hydrozoa
Feathery or Bushy colonies of tiny polypsPolyps may be specializedAttach to pilings, shells, seaweed, etc.Siphonophores - hydrozoans that form
drifting colonies (Portugues man of war)
Scyphozoans - Class Scyphozoa
Larger jellyfishBell of some medusae may reach 2 m.Some are the most dangerous in the world
Anthozoans - Class Anthozoa
Solitary or colonial polyps that lack a medusa stage.
Sea anemonesStony corals and sea fans