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1. Any of numerous solitary or colonial hydrozoans having a polyp rather than a medusa as the dominant stage of the life cycle.
2. The asexual polyp in the life cycle of a hydrozoan.

hy′droid′ adj.


1. (Animals) of or relating to the Hydroida, an order of colonial hydrozoan coelenterates that have the polyp phase dominant
2. (Zoology) (of coelenterate colonies or individuals) having or consisting of hydra-like polyps
(Zoology) a hydroid colony or individual
[C19: from hydra + -oid]


(ˈhaɪ drɔɪd)

1. of or pertaining to the hydrozoan order Hydroidea, including hydras and marine colonial forms.
2. the phase of hydrozoan development that consists of polyp forms.
[1860–65; hydr(a) + -oid; compare New Latin Hydroidea]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.hydroid - colonial coelenterates having the polyp phase dominanthydroid - 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
References in periodicals archive ?
However, some competent hydroid and gastropod larvae metamorphosed after being stressed with increased temperatures (Kroiher et al.
Hydroids at intertidal rocky fringes usually occur in sheltered microhabitats, such as tide pools or on macroalgae, that serve as natural refuges from extreme seasonal and daily temperatures and prevent hydroid colony desiccation (Genzano, 1994; Gili & Hughes, 1995).
Caption: This oaten pipes hydroid (Tubularia indivisa) is part of new exhibit of glass sea invertebrates.
Its offerings comprise the Hydroid REMUS series, purchased in a buyout in 2007, and its own Seaglider, HUGIN and MUNIN systems.
Further spread north of this species should be closely monitored and may depend on a different mechanism, such as chance rafting of adults or egg masses on drift macro-algae or other floating substrata supporting growths of it hydroid prey.
The company's offering includes the Remus 600 and the smaller portable Remus 100, both from Kongsberg Hydroid.
Currently, I am studying large-scale transport of biota on marine debris along with Dale Calder (curator emeritus of Invertebrate Zoology at the ROM, and, like me, a hydroid taxonomist).
Substrate Month, Locality Station year Hydroid May-09 Chelem 5 Halodule wrightii Nov-08 Chelem 5 Halodule wrightii May-08 Chelem 5 Batophora oerstedii Nov-08 Chelem 6 and B.
Yet another possible form of adaptation to the Arctic marine environment is represented by a microscopically observed association of the red alga Rubrointrusa membranacea (Magnus) Clayden and Saunders and benthic Arctic hydroid Sertularia sp.
The influence of the epizoic hydroid Hydractinia angusta on the recruitment of the Antarctic scallop Adamussium colbecki.
It looks like a jellyfish but is a closely-related hydroid, and each 'animal' is in fact made up of a colony of individuals.