. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LARVAL HATCHING IN AN ESTUARINE CRAB 199 Day 1 Day 2 Day 3 Day 4 96 h 600 n. Figure 10. Hatching of egg-clusters from which the cellophane skirt was removed before transfer into aeration, (a) Hatching of cl:F-46. Embryo exchange between F-45 and F-46 at 17:25-17:40 on 9 August. Larval release: F-45. at 23:45 on 10 August; F-46. at 23:50 on 12 August. (/») Hatching of cl:F-48. Embryo exchange between F-47 and F-48 at 14:25-14:35 on 9 August. Lar\al release: F-47. at 1:30 on 1 1 August: F-48. at 1:50 on 15 August, d) Hatching
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LARVAL HATCHING IN AN ESTUARINE CRAB 199 Day 1 Day 2 Day 3 Day 4 96 h 600 n. Figure 10. Hatching of egg-clusters from which the cellophane skirt was removed before transfer into aeration, (a) Hatching of cl:F-46. Embryo exchange between F-45 and F-46 at 17:25-17:40 on 9 August. Larval release: F-45. at 23:45 on 10 August; F-46. at 23:50 on 12 August. (/») Hatching of cl:F-48. Embryo exchange between F-47 and F-48 at 14:25-14:35 on 9 August. Lar\al release: F-47. at 1:30 on 1 1 August: F-48. at 1:50 on 15 August, d) Hatching of cl:F-50. Embryo exchange between F-49 and F-50 at 19:10-19: 20 on 9 August. Larval release: F-49. at 0:20 on 10 August: F-50. at 2:20 on 15 August. Downward arrows indicate time of dav of release bv the host females. hatching process, and not hatching itself. If the hatching process is not initiated at a certain acrophase (Fig. 12). the embryos must wait until the next allowed zone to start the process. Induction of hatching in the transplanted cluster While each embryo has an endogenous rhythm of hatching, the present study indicates that the hatching of exchanged clusters is induced by the host female, provided that the incubation was longer than 5-6 h (compare Figs. 6A, 7A and 9B). Since the start of the hatching process may be a gated event, it is reasonable to speculate that this process begins h before the hatching, re- sponding to some signal to each embryo. But we do not know what stimuli trigger the hatching process in each embryo. One possibility is mechanical stimuli generated by the female—perhaps some special movements of the abdomen or ovigerous setae as the embryonic develop- ment is completed. Another possibility is a hatch-inducing substance, produced by the female and recognized by the embryos. We also do not know when hatch-inducing stimuli are released from the female. Females could gen- erate such stimuli at any time of day, or at a particular
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
