Orientation Mechanisms of Marine Turtles

Abstract

The principal mechanism in the sea-finding orientation of hatchling turtles when they move from the nest to the water is based on a phototropotactic reaction to light and a complex balancing of stimulation to different retinal areas and corresponding regions of the optic tectum. Transient potentiation of parts of this system occur following abrupt changes in illumination. In contrast to guidance systems that demand fine resolution of stimuli, sea-finding depends on integration of information, integration both over space (wide field of view) and over time (averaging illumination over about 1 s). Sea-finding of turtles when on land is relevant to their movements when in the water since there may be some calibration of other guidance systems against headings initiated by the sea-finding mechanisms.