Photic entrainment of circadian activity patterns in the tropical labrid fish Halichoeres chrysus.

@article{Gerkema2000PhoticEO,
  title={Photic entrainment of circadian activity patterns in the tropical labrid fish Halichoeres chrysus.},
  author={Menno P Gerkema and John J Videler and J de Wiljes and H van Lavieren and Hans G. Gerritsen and Martin Karel},
  journal={Chronobiology international},
  year={2000},
  volume={17 5},
  pages={613-22}
}
Yellow wrasses (Halichoeres chrysus) show clear daily activity patterns. The fish hide in the substrate at (subjective) night, during the distinct rest phase. Initial entrainment in a 12h:12h light-dark (12:12 LD) cycle (mean period 24.02h, SD 0.27h, n = 16) was followed by a free run (mean period 24.42h, SD 1.33h) after transition into constant dim light conditions. Light pulses of a comparable intensity as used in the light part of the LD cycles did not result in significant phase shifts of… CONTINUE READING