Hydrozoa

Hydrozoa
    n 1: coelenterates typically having alternation of generations;
         hydroid phase is usually colonial giving rise to the
         medusoid phase by budding: hydras and jellyfishes [syn:
         {Hydrozoa}, {class Hydrozoa}]
    

Hydrozoa \Hy`dro*zo"a\, n. pl. [NL., fr. E. hydra + Gr. zo^,on
   an animal.] (Zool.)
   The Acaleph[ae]; one of the classes of c[oe]lenterates,
   including the Hydroidea, Discophora, and Siphonophora.
   [1913 Webster]
    

Hydrozoon \Hy`dro*zo"["o]n\, n.; pl. L. {Hydrozoa}, E.
   {Hydrozo["o]ns}. [NL.] (Zool.)
   One of the Hydrozoa.
   [1913 Webster]
    

{Molluscoidea}, including Brachiopoda and Bryozoa. {Mollusca},
including Cephalopoda, Gastropoda, Pteropoda, Scaphopoda,
Lamellibranchiata or Acephala. {Echinodermata}, including
Holothurioidea, Echinoidea, Asterioidea, Ophiuroidea, and
Crinoidea. {C[oe]lenterata}, including {Anthozoa} or {Polyps},
{Ctenophora}, and {Hydrozoa} or Acalephs. {Spongiozoa} or
{Porifera}, including the sponges.
{Protozoa}, including {Infusoria} and {Rhizopoda}. For
definitions, see these names in the Vocabulary.
[1913 Webster] Animalcular