Burrow plugging by the fiddler crab Uca uruguayensis and its synchronization with two environmental cycles: photoperiod and tide cycle

DE LA IGLESIA, H.O.; RODRÍGUEZ, E.M.; DEZI, R.E.

PHYSIOLOGY AND BEHAVIOR

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1994 vol. 55 p. 913 - 919

0031-9384

Field observations and laboratory experiments were performed to analyze the burrow plugging behavior of U. uruguayensis and to analyze its relation to two environmental cycles: light-dark cycle and tides. Field observations showed that burrow plugging is a rhytmic behavior synchronized with both environmental cycles such that the burrows are open during those periods of simultaneous light and low tide. Laboratory experiment sugested that the plugging rhytm is under endogenous circadian control, whereas its synchronization with the tidal cycle, particularly with periodic inundation, seems to be strongly exogenous, not showing clear circatidal components. It is proposed that burrow plugging is adaptive because it allows the animals to be within an air medium, more suitable for their respiration modality, during high tide and because it prevents burrrow collapse. It is also propropsed that both the endogenous circadian component and the lack of an endogenous circatidal component can also be explained on the basis of adptive value, taking into account the regular tempral structure of the solar day and the irregular temporal structure of the tidal cycle.