Phylum Cnidaria.
<P>
   Cnidarians  are  diploblastic and may exist in polyp and medusa stages
   in their life cycle.
<P>
   Tentacles are armed with cnidocytes to capture prey.
<P>
<BR><LI> class Hydrozoa
<BR><LI> class Scyphozoa
<BR><LI> class Cubozoa
<LI> class Anthozoa