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Any of various cnidarians of the class Hydrozoa, including the hydras, hydroids, and siphonophores, which exhibit alternation of generations between the polyp and medusa stage or exist in only one or the other stage.

[From New Latin Hydrozōa, class name : Hydra, type genus; see hydra + -zōa, pl. of -zōon, -zoon.]

hy′dro·zo′an adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Animals) any colonial or solitary coelenterate of the class Hydrozoa, which includes the hydra, Portuguese man-of-war, and the sertularians
(Animals) of, relating to, or belonging to the Hydrozoa
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˌhaɪ drəˈzoʊ ən)

1. any freshwater or marine cnidarian of the classHydrozoa, including attached and free-swimming, often colonial, forms in which the medusa stage is reduced or lacking.
2. belonging or pertaining to the hydrozoans.
[1875–80; < New Latin Hydrozo(a) (see hydro-1, -zoa) + -an1]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.hydrozoan - colonial coelenterates having the polyp phase dominanthydrozoan - colonial coelenterates having the polyp phase dominant
cnidarian, coelenterate - radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms
planula - the flat ciliated free-swimming larva of hydrozoan coelenterates
class Hydrozoa, Hydrozoa - coelenterates typically having alternation of generations; hydroid phase is usually colonial giving rise to the medusoid phase by budding: hydras and jellyfishes
hydra - small tubular solitary freshwater hydrozoan polyp
siphonophore - a floating or swimming oceanic colony of polyps often transparent or showily colored
sertularian - feathery colony of long-branched stems bearing stalkless paired polyps
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
One striking example of this concept was seen in research with the hydrozoan Hydra, where environmental and laboratory-reared organisms harbored the same microbiota (Fraune & Bosch 2007).
This corresponds to ~9% (26 of 295 species recorded) and less than 1% (26 of 3,428 species recorded) of the hydrozoan species recorded for the Argentinean Patagonia and worldwide, respectively (Oliveira et al, 2016; Schuchert, 2016), showing that the knowledge on the biodiversity of hydroids at intertidal habitats of Argentinean Patagonia is still scarce.
As shown in Table 4, some of the classes such as hydrozoan, acorn barnacle, algae, finger sponge, and Christmas tree worm produced a result of less than 70%, which as mentioned above was set as the benchmark for what is acceptable.
But this hydrozoan, common in the western Mediterranean and Adriatic seas, is something of a cheat.
Human nature, this time (as opposed to hydrozoan) about which I ponder a LOT.
The specimens were identified as the crawling medusa, Eleutheria dichotoma, which is one of a small group of hydrozoan medusae that crawls on algae rather than swimming in the plankton.
The endozoic association and its diminutive tetrasporic filaments likely represent an advantageous adaptation to low incident light, which is further reduced in quality and quantity by the hydrozoan exosarc cover.
"The discovery of green fluorescent protein in a hydrozoan jellyfish in the 1960s has provided a revolutionary tool for modern biologists, transforming our study of everything from the AIDS virus to the workings of the brain," Gruber said.
and others, Patterns in marine hydrozoan richness and biogeography around southern Africa: implications of life cycle strategy.
For example, throughout earth history, genuine scyphozoan, hydrozoan, or cubozoan medusae are only known from [less than or equal to] 10 deposits, all of which are significant or potential Konservatlagerstatten (Young and Hagadorn 2010).
The 4-5mm diameter creature, technically known as a hydrozoan, is the only known animal that is capable of reverting to its juvenile polyp state.