. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 258. M. SAIGUSA B controller event (with switch) recorder original record (15July. 1990) Time of day (h) £3 = I -= ' *rL 4 -u— • ! ' b a — t . b TT controller Figure 1. System for recording the larval release activity of Sesarma pictum females. A. The apparatus used to detect the time of day of larval release, w: fine wire, pc: plastic cage to confine an ovigerous crab, s and r: infrared source and receiver (E3S-2E4, Omron Co. Ltd., Japan). The glass beaker illustrated here is the larger one ( cm diameter; see text). B.
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 258. M. SAIGUSA B controller event (with switch) recorder original record (15July. 1990) Time of day (h) £3 = I -= ' *rL 4 -u— • ! ' b a — t . b TT controller Figure 1. System for recording the larval release activity of Sesarma pictum females. A. The apparatus used to detect the time of day of larval release, w: fine wire, pc: plastic cage to confine an ovigerous crab, s and r: infrared source and receiver (E3S-2E4, Omron Co. Ltd., Japan). The glass beaker illustrated here is the larger one ( cm diameter; see text). B. An example of an original record showing 4 out of 17 females releasing their larvae (a part of the data illustrated in Figure 2). The output of the sensor unit was monitored by an event recorder (R17-H12T, Fuji Electric Co. Ltd., Japan) through a controller (S3S-A-10, Omron). a: time of larval release by a female, b: time when that female was removed from the experimental chamber with her beaker. Simultaneously, a new beaker with a plastic cage that confined another ovigerous female was placed in each apparatus. this species has a tidal rhythm with a bimodal phase ( h period) that has no apparent circadian component. The present paper asks whether this tidal rhythm is also af- fected by the day-night cycle, and it discusses possible mechanisms for this influence. Materials and Methods Sesarma pictum inhabits banks above the water's edge in the intertidal zone. Male and female crabs spend the winter hibernating in burrows dug into the bank, but they become active in the latter half of April. In early summer (June-July), the females incubate their eggs in their folded abdomens, where the embryos are ventilated by move- ments of the pleopods. When embryonic development is completed, the females enter the water to liberate their zoea larvae. The larval release behavior has not been ob- served in the field because it is not carried out at the water's edge, as is that of
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
