The Water-Finding Ability of Sea Turtles
Behavioural Studies and Physiological SpeculationsMrosovsky N.
Departments of Psychology and Zoology, University of Toronto, Toronto
Dr. N. Mrosovsky, Departments of Psychology and Zoology, University of Toronto, Toronto (Canada)
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Field experiments with hatchling green sea turtles (Chelonia mydas) show that a positive phototropotaxis will account for many aspects of their ability to find the sea after emerging from the nest. The tropotactic reaction is discussed with respect to retino-tectal projections in reptiles and it is suggested that visual stimulation of one eye may initiate both ipsilateral and contralateral turning tendencies, depending on which part of the retina is stimulated. The influence of the sun''s position and the effects of varying the spectral composition of light stimuli are outlined. Some complexities in experiments on the responses to light of frogs (Rana temporaria) and freshwater turtles (Pseudemys scripta elegans) are reported, and it is concluded that for correlating behaviour with physiological mechanisms a more dependable behaviour such as sea-finding in marine turtles offers some advantages.
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