. The Biological bulletin. Biology; Zoology; Marine biology. CONTROL OF EMERGENCE OF PINK SHRIMP 55 The ejects of feeding and starvation on emergence The pattern of emergence of a group of 40 shrimp which had not been fed for four days was compared with that of an equivalent group, maintained under identical conditions but which were fed each day after the onset of the dark period. For the purposes of this experiment emergence was recorded when a light-dark transition was imposed at a time (10:00 hrs.) out of phase with the time to which they had been entrained to emerge (18:00 hrs.). The resu
. The Biological bulletin. Biology; Zoology; Marine biology. CONTROL OF EMERGENCE OF PINK SHRIMP 55 The ejects of feeding and starvation on emergence The pattern of emergence of a group of 40 shrimp which had not been fed for four days was compared with that of an equivalent group, maintained under identical conditions but which were fed each day after the onset of the dark period. For the purposes of this experiment emergence was recorded when a light-dark transition was imposed at a time (10:00 hrs.) out of phase with the time to which they had been entrained to emerge (18:00 hrs.). The results (not detailed here) showed that in two out of three repetitions the rate and degree of emergence of the unfed shrimp were greater than those of the fed shrimp. On the third occasion there was no noticeable difference between the two groups. These results suggest that the difference in the time taken to. 1100 1200 1300 1400 1500 1100 1200 TIME OF DAY 1300 1400 1500 Figure 7. The emergence during the day of two groups of shrimp (A and B) subjected to different feeding schedules. On day 1, group A (O O) was fed during the light period (13:00 hrs.); while group B (A A) was fed immediately after the light-dark transition (19:45 hrs.). Consequent emergence patterns are shown for day 2. Later on day 2, group A was fed at 19:45 and group B at 13:40—, the times of feeding were reversed. Their emergence is shown for the following day, day 3. (Note: shrimp were deprived of food for 3 days before day 1.) resynchronize the rhythms of the fed and the unfed shrimp, following phase shifting of the external light cycle, was not a result of depression of activity caused by starvation. Evidence for a feeding rhythm Two groups (A and B), each comprising 30 shrimp, were used in this experi- ment. They were both held under identical conditions (LD 13^; 10^) but were fed at different times. To separate emergence, which could be the result of a feeding rhythm, from normal nocturnal emergence
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