. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 118 N. B. RUSHFORTH AND F. HOFMAN of the stimulated tentacle and concerted oral flexions of the rest of the tentacles. With greater stimulation, by multiple Artcuiia or GSH, the tentacle activities con- sist of uncoordinated writhing movements for extended time periods, gradually giving rise to concerts. During this behavioral sequence, the normal spontaneous contraction activities of the tentacles are suppressed. Those contractions are gradually restored to prestimulation levels, approximately 15 minutes after Artcniia engu
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 118 N. B. RUSHFORTH AND F. HOFMAN of the stimulated tentacle and concerted oral flexions of the rest of the tentacles. With greater stimulation, by multiple Artcuiia or GSH, the tentacle activities con- sist of uncoordinated writhing movements for extended time periods, gradually giving rise to concerts. During this behavioral sequence, the normal spontaneous contraction activities of the tentacles are suppressed. Those contractions are gradually restored to prestimulation levels, approximately 15 minutes after Artcniia engulfment (Fig. 5). 5 ARTEMIA IT) CAPTURED \ (/> O O tr h- o o LJ _J O I LJ h- L_ O o: LJ m 0 5 10 15 20 TIME IN MINUTES FIGURE 5. Effects of exposure to live Arteinia on the frequency of tentacle contraction in H. littoralis; number of tentacle contractions/animal/5 min, 15 min before and after capture of a single Arteinia, for a group of 10 hydra. (b). Column contractions. Column contraction is perhaps the most striking spontaneous activity of hydra. In H. pirardl most contractions occur in bursts, while in //. pseudoligactis contractions tend to occur as single widely-spaced events (Rushforth, 1971). In H. littoralis the temporal pattern of contraction activity appears intermediate between that of these two species (Rushforth, 1966). With all species, contractions of the body column are inhibited during feeding (Rush- forth et al., 1964). The results of the following experiments clearly show that such inhibition is chemically mediated. One group of 10 hydra was flooded with a large number of Arteinia salhia nauplii and the hydra were allowed to feed for a 15 minute period. If the culture water was not changed at this point, the column contraction frequencies were significantly lower (P < ) than those. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrat
Size: 1571px × 1591px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
