How Turtles Find the Sea

Abstract

and Summary Hatchling turtles, after emerging from their nests on the beach, move towards the sea. One explanation of this sea‐finding ability is that there is a complex phototropotactic reaction to light; this initiates turning until sub‐components of the system receive equal input. Another explanation is that the direction of peak excitation is located instantaneously and that the turtles then head in that direction. This paper reports new experiments on the behaviour of loggerhead turtles (Caretta caretta) wearing partial blindfolds: their poor orientation, even after several hours time for adaptation to the blindfolds, supports the phototropotaxis hypothesis. Data on loggerhead, leatherback (Dermochelys coriacea) and green turtle (Chelonia mydas) hatchlings released under clear skies confirm that the position of the sun does influence orientation. Experiments on loggerheads with wax paper over their eyes show that form vision is not essential for sea‐finding. The possibility of mechanisms additional to and redundant with a complex phototropotactic system or a direction locating system are considered but rejected as unlikely.

Synchronous activity lowers the energetic cost of nest escape for sea turtle hatchlings

“…It is well known that hatchling sea turtles use light cues to direct their movement once they exit the nest in nature (e.g. Mrosovsky and Kingsmill, 1985;Kawamura et al, 2009), and it appears that they can be attracted to light even while buried underground, but in nature such cues are absent during the nest escape process. Thus, in the final experimental protocol, we used light-proof PVC pipe as our respiratory chambers.…”

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Responsible Leadership as Virtuous Leadership

“…The heliotropic effect is the attraction of all living systems toward positive energy and away from negative energy, or toward that which is life-giving and away from that which is lifedepleting (Smith and Baker 1960;D'Amato and Jagoda 1962;Mrosovsky and Kingsmill 1985). In nature, this is exemplified by light from the sun.…”