. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LARVAL HATCHING OF A TERRESTRIAL CRAB 403 a pipette. This exchange of beakers was made during the dark phase under the illumination of a hand-held flashlight covered with red cellophane. Each female from which some embryos had been de- tached was also monitored, and the time of larval release recorded. The recording system consisted of a sensor unit (infrared source-receiver) and a controller unit with a photoelectric switch. The sensor unit was placed in the experimental room, and the controller unit was set outside the roo
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LARVAL HATCHING OF A TERRESTRIAL CRAB 403 a pipette. This exchange of beakers was made during the dark phase under the illumination of a hand-held flashlight covered with red cellophane. Each female from which some embryos had been de- tached was also monitored, and the time of larval release recorded. The recording system consisted of a sensor unit (infrared source-receiver) and a controller unit with a photoelectric switch. The sensor unit was placed in the experimental room, and the controller unit was set outside the room. The larval release could thus be monitored without a change in ambient light. The female was con- fined in a perforated plastic cage suspended from the rim of a 1 or 2 1 glass beaker containing diluted, clean seawater (500 or 750 ml; salinity at about 10%o). Only the bottom of the beaker was immersed in the water. When the larvae were released, they fell through the perforations and into the beaker, where they triggered the photoelectric switch. The output of this system was monitored by an event recorder (Saigusa. 1986). Females release their larvae as soon as hatching is completed, so the time of release clearly marks the completion of hatching. The time of day that each female released her attached larvae was compared with the time of hatching from the eggs that had been detached from her. However, the day during which a female released her larvae could not be precisely estimated. The signs of hatching only appear on the day of larval release (, a few zoeas begin to swim in the glass beaker only a few hours before larval release). Many of the data were like those set out in the upper two sections of Table I. Hence, many comparisons of detached and attached embryos were necessary; 250 samples from 110 females were examined. Results 18 Time of day 24 20,000-1 o N 10,000- 16,200 6,870 0:40 •D 60- O) .c u ni 40- N = 476 _c in 8 20- 0) O o~" f. Sept. 5 Sept. 6
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
