International Journal of Comparative Psychology

According to the “lost year” theory of sea turtle development, hatchlings swim offshore in a frenzy until they reach floating weed beds where they live in relative safety for the first few years of life. Direct observations of post hatchlings in nature have been rare, so we utilized very young captive hatchlings presented with open water or artificial weed bed habitats (Experiments 1 and 2). Loggerhead ( Caretta caretta ) and hawksbill ( Eretmochelys imbricate ) hatchlings congregated in the weed bed, but green ( Chelonia mydas ) hatchlings did not. Green hatchlings that were slightly older and presented with sargassum continuously did show more tendency to gather in the weeds, particularly at night (Experiment 3). The young green turtles oriented towards the open ocean and congregated in the end of the tank closest to the ocean and actively avoided weeds (Experiments 4 and 5). When hatchlings were given simulated predation experience the loggerheads and hawksbills remained immobile following prediction, but the greens actively swam away (Experiment 6 and 7). These results suggest that the lost year theory of sea turtle development must be refined to take into account species differences and that different species of post hatchlings in nature may be found in different microhabitats, and reacting differently to potential and actual threat of predation.