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n.1.(Zool.) The hollow stem of a hydroid, either simple or branched. See Illust. of Gymnoblastea and Hydroidea.
References in periodicals archive ?
thickening of the hydrocaulus in species of Leptothecata) to specific environments, such as intertidal habitats, where the water movements are stronger (e.
japonica and C', mashikoi are differentiated by the distinct annulations on the hydrocaulus of the latter (Ito, 1952).
All clams were scored for the presence or absence of the hydroid and the length of the largest hydrocaulus of the colony was measured.
Hydrocaulus monosiphonic; each branch arising from a slightly curved aphophysis given off below hydrothecae of pedicel from which if arises.