Reproduction
 |
Movie of a sea turtle laying eggs:
Courtship and Mating:
Courtship activities usually occur several weeks before the nesting season and two or more males may court a single female. Males may court a female by nuzzling her head or by gently biting the back of her neck and rear flippers. If the female does not flee, the male attaches himself to the back of the females shell by grasping her top shell with his enlarged claws on his front flippers. Then he folds his tail under her shell to copulate. Copulation can take place either on the surface or under water just offshore. Fertilization is internal.
Nesting Behavior:
Female sea turtles come ashore to lay eggs. They nest a few weeks after mating. They usually nest during the warmest months of the year, except for the Leatherbacks, which nest in fall and winter. Most females return to the same nesting beach each year. They usually come ashore alone at night, during high tide. She then constructs a "body pit" by digging with her flippers and rotating her body. She then uses her hind legs to dig an egg cavity.
 |
Then she begins to lay the eggs. Depending on the species, the female turtle can deposit between 50 and 200 eggs, but the average size of a clutch is usually between 80 and 120 eggs. The eggs are released 2 or 3 at a time with mucus to cushion them. The eggs are soft-shelled, and are papery and leathery in texture.
 |
Then the female covers the nest with sand using her hind flippers. By burying the eggs the female is protecting the eggs from surface predators, she is keeping the soft, porous shells moist therefore protecting them from drying out, and she is keeping them at the proper temperature. Females usually lay between one and nine clutches(groups) of eggs per season. Once the female leaves her nest, she never returns to tend it.
Incubation and Hatching:
Incubation can take anywhere from 45 days to 70 days. Cooler sand has a tendency to produce more males, while warmer sand produces a higher ratio of females. Hatchlings use a temporary, sharp egg-tooth, called a caruncle to help break open the shell. After hatching, the young sea turtles may take three to seven days to dig to the surface. Hatchlings usually emerge from their nest at night or during a rainstorm when it is cooler. They usually emerge from the nest cavity as a group. The turtles find the brightest horizon and then dash toward the sea. When the hatchlings reach the surf, they dive into the waves and rides the undertow out to sea. Only about one in 1,000 survives to adulthood.
 |
 |
Emerging from the nest |
The race to sea |