Two other classes, Scyphozoans and Hydrozoans, are far more dangerous to humans due to their deployment of nematocytes during their medusoid stages.
A debate exists as to whether the parasitic Myxozoa belong to this phylum, of which one of the classes is differentiated from the other three by their body type never leaving the polyp stage. Members of that class, the Anthozoa, do contain the defense mechanism common to the phylum, but apparently lack the delivery mechanism capable of making it harmful to humans, and many of them are dependent on a symbiotic relationship with dinoflagellates. Two other classes, Scyphozoans and Hydrozoans, are far more dangerous to humans due to their deployment of nematocytes during their medusoid stages. FTP identify this phylum formerly known as Coelenterata but now named for an alternate term for their stinging cells, which includes sea fans, corals, anemones, and jellyfish.
A debate exists as to whether the parasitic Myxozoa belong to this phylum, of which one of the classes is differentiated from the other three by their body type never leaving the polyp stage.
Cnidaria [prompt on "Coelenterata" before that is read]