Five of 8 sea turtle species living in the world are found in the Mediterranean, whereas only 2 of these (Caretta caretta and Chelonia mydas) regularly nest in the Mediterranean.
C.caretta matings may occur near the nesting beaches or in special gathering areas a few weeks prior to the beginning of the nesting season. Mating pairs are frequently seen at the surface, although there are reports of submerged copulations.
Nesting season in the northern hemisphere is generally from May to August. Laying eggs usually takes place at night, and rarely during mornings. The female occasionally raises her head to view the beach while approaching the beach to nest. At this stage, the turtle is extremely sensitive to external stimuli and will immediately swim away in case of any disturbance. Once the female finishes digging a nest and starts laying her eggs, she is not as sensitive to stimuli. When egg depositing is completed, rear flippers help cover the eggs gently with the moist sand dug out and press the sand. Finally, the female starts crawling forward while front flippers throw sand backwards to form a camouflaged area to hide the egg chamber. Once this entire process is completed, the female hastily returns to the sea.
Sea turtles generally nest every 2-3 years. They may nest for more than once in one nesting season. The interval between two nestings in the same season is about 2 weeks.
Freshly laid sea turtle eggs are generally spherical, white, soft, coated with a mucous secretion and the size of a ping-pong ball (about 40 mm in diameter and 40 grams). The clutch size in a nest is approximately 100, and the incubation period lasts for 1.5-2 months.
Hatchlings lie still in the nest for a while and leave the nest in 5 days on average by helping each other to scramble up in the sand. Hatchlings leaving their nests orient towards the sea by making use of the brightness of the horizon and the reflection of the moon on the water’s surface. Any kind of artificial light behind the beach during that period may disorient hatchlings leading to extensive mortality.