The Phylum Cnidaria contains three classes that differ depending
on which phase of the life cycle, the polyp or medusa, is expressed. In
general, the polyp form is anchored with tentacles pointing upward and
the medusa form is free-floating with tentacles pointing downward. Stinging
cells, or nematocysts, are characteristic of the Cnidarians. The three
Class Hydrozoa-- the polyp phase is dominant and
the medusa is reduced or absent from the life cycle. The symmetry is radial.
This class includes the fire corals, hydroids, and siphonophores. One hydrozoan,
Millepora, the fire coral, is included in this activity.
Class Scyphozoa-- the medusa stage is dominant
and polyps are rarely formed. This class is composed primarily of the jellyfishes.
Class Anthozoa-- large, often elaborate polyps
or colonies of polyps form. A medusa stage is never present. This class
includes sea anemones, soft corals and stony corals. The Anthozoa, specifically
the Zoantharia (stony corals), are the focus of this activity.
List of Corals Included
Unknowns from the NMITA database
NMITA coral identification
Last updated on October 17, 1997-jlc.