hydranth


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hydranth

[′hī‚dranth]
(invertebrate zoology)
Nutritive individual in a hydroid colony.
References in periodicals archive ?
Hydranth soft brown or pale, small, cylindrical, about 320 [micron]m from diaphragm to tentacles.
Hydranth short, cylindrical, about 150 [micron]m long, with 25-38 tentacles, each 220-240 [micron]m long.
Hydrothecal margin slightly crenate, 14-16 sort tooth, hydranth cylindrical Obelia dichotoma 5b.
Therefore, means were calculated for each nematocyst type from each hydranth so that each population had 8 means per nematocyst type.
Population P Mean Standard Mean Difference value ([mu]m) deviation hydranth SD of hydranth ([mu]m) ([mu]m) SD ([mu]m) CL 0.
Colonies also grow asexually by producing additional hydranths to the upright branches (hydrocauli) or by extending the attached stolons (hydrorhiza) that then produce more hydrocauli and hydranths (Kinne, 1958; Fulton 1962; Jormalainen et al.
Two to four hydranths were picked from a single colony and DNA was extracted using the Qiagen DNeasy kit, following the manufacturer's protocol for purification of total DNA.
It was found that the basal ends of the (A) pieces did not develop faster than those of the (B) pieces, showing that the changes at the basal end of (A) are not progressing, but are held in check by the developing oral hydranth.
In order to find out whether, when the oral end is tied, changes take place throughout the piece that tend to make more rapid the development of basal hydranths, or whether these changes are localized at the basal end where the new hydranth develops, the following experiment was tried.
After 23 hours the hydranth region at the oral end was cut off of some pieces (A), others were cut in two in the middle of the piece (B), and for a control some pieces were left as before (C).
It is interesting to note that in both the influence of the cutting causes a greater delay in the first appearance of the primordia of the hydranth than on their later development; for later the differences seem to be less than at first.
The number of unhealthy looking zooxanthellae per hydranth digestive cell showed a broad peak at about midnight (four highest data points = 1.