Actinozoa
Actinozoa is an obsolete term in
systematic zoology, first used by
Henri Marie Ducrotay de Blainville about 1834, to designate animals the organs of which were disposed radially about a centre.De Blainville included in his group many unicellular forms,
sea anemones,
corals,
jellyfish,
hydroid polyps,
echinoderms,
polyzoa and
rotifera.
Thomas Huxley afterwards restricted the term. He showed that in de Blainville's group there were associated with a number of
heterogeneous forms a group of animals characterized by being composed of two layers of cells comparable with the first two layers in the development of vertebrate animals. Such forms he distinguished as Coelentera, and showed that they had no special affinity with echinoderms, polyzoa, etc. He further divided the Coelentera into a group
Hydrozoa, in which the sexually produced embryos were usually set free from the surface of the body, and a group Actinozoa, in which the embryos are detached from the interior of the body and escape generally by the oral aperture. Huxley's Actinozoa comprised the sea-anemones, corals and
sea pens, on the one hand, and the
Ctenophora (comb jellies) on the other.
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Actinozoa
Noun
1. no alternation of generations the medusoid phase being entirely suppressed: sea anemones; corals
(synonym) Anthozoa, class Anthozoa, class Actinozoa
(hypernym) class
(member-holonym) Cnidaria, phylum Cnidaria, Coelenterata, phylum Coelenterata
(member-meronym) anthozoan, actinozoan
Actinozoa
(n. pl.)
A group of Coelenterata, comprising the Anthozoa and Ctenophora. The sea anemone, or actinia, is a familiar example.
Webster's Revised Unabridged Dictionary (1913), edited by Noah Porter.
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