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The Collaborative International Dictionary

Hydrozoon \Hy`dro*zo"["o]n\, n.; pl. L. Hydrozoa, E. Hydrozo["o]ns. [NL.] (Zo["o]l.) One of the Hydrozoa.


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


Animal \An"i*mal\, a. [Cf. F. animal.]

  1. Of or relating to animals; as, animal functions.

  2. Pertaining to the merely sentient part of a creature, as distinguished from the intellectual, rational, or spiritual part; as, the animal passions or appetites.

  3. Consisting of the flesh of animals; as, animal food.

    Animal magnetism. See Magnetism and Mesmerism.

    Animal electricity, the electricity developed in some animals, as the electric eel, torpedo, etc.

    Animal flower (Zo["o]l.), a name given to certain marine animals resembling a flower, as any species of actinia or sea anemone, and other Anthozoa, hydroids, starfishes, etc.

    Animal heat (Physiol.), the heat generated in the body of a living animal, by means of which the animal is kept at nearly a uniform temperature.

    Animal spirits. See under Spirit.

    Animal kingdom, the whole class of beings endowed with animal life. It embraces several subkingdoms, and under these there are Classes, Orders, Families, Genera, Species, and sometimes intermediate groupings, all in regular subordination, but variously arranged by different writers.

    Note: The following are the grand divisions, or subkingdoms, and the principal classes under them, generally recognized at the present time: Vertebrata, including Mammalia or Mammals, Aves or Birds, Reptilia, Amphibia, Pisces or Fishes, Marsipobranchiata (Craniota); and Leptocardia (Acrania). Tunicata, including the Thaliacea, and Ascidioidea or Ascidians. Articulata or Annulosa, including Insecta, Myriapoda, Malacapoda, Arachnida, Pycnogonida, Merostomata, Crustacea (Arthropoda); and Annelida, Gehyrea (Anarthropoda). Helminthes or Vermes, including Rotifera, Ch[ae]tognatha, Nematoidea, Acanthocephala, Nemertina, Turbellaria, Trematoda, Cestoidea, Mesozea. 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.


n. (context biology English) a large group of marine animals, of the class ''Hydrozoa'', whose life cycles contain a sexual and asexual stage

  1. n. colonial coelenterates having the polyp phase dominant [syn: hydroid]

  2. [also: hydrozoa (pl)]


See hydrozoan


Hydrozoa (hydrozoans, from ancient Greek ὕδρα, hydra, "sea serpent" and ζῷον, zoon, "animal") are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most living in salt water. The colonies of the colonial species can be large, and in some cases the specialized individual animals cannot survive outside the colony. A few genera within this class live in fresh water. Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria.

Some examples of hydrozoans are the freshwater jelly ( Craspedacusta sowerbyi), freshwater polyps ( Hydra), Obelia, Portuguese man o' war (Physalia physalis), chondrophores (Porpitidae), " air fern" (Sertularia argentea), and pink-hearted hydroids ( Tubularia).

Usage examples of "hydrozoa".

The Corviki resemble a marine animal in the class hydrozoa, sort of a large sac-like body with a complex collection of tendrils that may be nerve endings.

Headley, that the groundwork here, so far as we can observe it through the dense growth of hydrozoa and silicious sponges, is pumicestone and the black slag of basalt, pointing to ancient plutonic activities.