Time-keeping system of the eel pout, Zoarces viviparus.
Observations on the rhythmic activity of 71 juvenile specimens of the inter-tidal blenny Zoarces viviparus reveal an endogenous pattern of swimming at three different periodicities. Circatidal swimming, with activity peaks phased to high water or the ebb of the subjective 12.4-h tides, was found in 50 fish and was the predominant pattern seen immediately after collection, when the rhythm generally persisted for between 3 and 12 cycles. Discrete activity peaks, with a free running period of approximately 24 h were also evident in the swimming pattern of eight fish. A circadian influence was also manifest as a modulation in amplitude, phase shifts and changes in free-running period of the circa-tidal rhythm. Overall, the activity level declined with time but those fish that remained active long enough showed a semi-lunar rhythm, with maximum activity at the time of the spring tides. A comparison of the behavior of animals collected at different times of the year suggests a seasonal variation in the persistence of circatidal swimming. The results are consistent with a control system involving circatidal, circadian, and semi-lunar oscillators.
School of Biosciences, University of Birmingham, Edgbaston, UK.
S M
SM
Cummings
E
E
Morgan
D000204:Activity Cycles / Q000502:physiology; D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology; D010473:Perciformes / Q000502:physiology*; D012621:Seasons; D013550:Swimming