The loggerhead turtle (Caretta- caretta) used to be common throughout Mediterranean, but its nesting grounds have been diminished, due to shore development; today this graceful swimmer is considered an endangered species.   Zakynthos is one of the last -and the most important- nesting areas in the Mediterranean for the loggerhead turtle.   The male turtle never leaves the sea but in the early summer the female comes to the south-coast beaches of Gerakas, Sekania, Dafni, Kalamaki, Laganas and Marathonisi to lay its eggs in the sand.   The young are hatched by the sun's heat and after 55 days crawl into the sea.   Special measures have been taken for the protection of the nests.   The information booths and message-boards in the nesting areas will provide you with detailed information about the ways you can help.