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Tidally rhythmic behaviour of marine animals
Symposia of the Society for Experimental Biology
|January 1, 1985
Summary
Coastal animals use internal biological clocks for tidal and daily behaviors, synchronized by environmental cues like salinity and light. These rhythms are controlled by physiological pacemakers and neurohormones, influencing activity patterns.
Area of Science:
- Marine Biology
- Chronobiology
- Animal Behavior
Background:
- Coastal animals exhibit 'spontaneous' tidal and daily behavioral patterns.
- These patterns are hypothesized to be controlled by an endogenous physiological pacemaker system.
- Environmental cues adjust these internal clocks to local time.
Purpose of the Study:
- To investigate the endogenous basis of tidal and daily rhythms in marine animals.
- To understand the mechanisms of entrainment and synchronization of these rhythms.
- To explore the role of neurohormones in modulating behavioral periodicity.
Main Methods:
- Demonstration of free-running endogenous rhythms under constant laboratory conditions.
- Entrainment experiments using simulated tidal variables (temperature, salinity, pressure, wave action).
- Neurophysiological recordings of neuroelectrical activity and hormone analysis.
Main Results:
- Free-running rhythms of circatidal, circadian, circasemilunar, and circalunar periodicity were observed.
- Salinity changes entrain the endogenous clock in crabs (Carcinus), with specific thresholds for entrainment.
- Neurodepressing hormone (NDH) in decapod crustaceans modulates neuroelectrical and behavioral rhythmicity.
Conclusions:
- Endogenous physiological pacemakers, adjusted by environmental cues, govern tidal and daily behaviors in coastal animals.
- Specific environmental variables like salinity and light intensity play crucial roles in entraining biological clocks.
- Neurohormonal mechanisms, such as NDH, are integral to the physiological basis of these rhythms.