Turtles do come from eggs. Like all reptiles, turtles reproduce by laying eggs, a fundamental characteristic distinguishing them from mammals and amphibians. This strategy is universal across all turtle species, regardless of habitat. Their eggs develop outside the mother’s body, relying on external conditions for incubation.
Laying the Eggs
Female turtles undertake a precise process to lay their eggs. They seek suitable nesting sites on land, often sandy beaches or areas with soft soil, for egg development. The female first digs a “body pit” with her front flippers, then excavates a flask-shaped egg chamber with her hind flippers. The chamber’s depth varies, reaching up to one meter for some sea turtle species, determined by her hind flippers’ length.
After preparing the nest, the female deposits her eggs, which are typically soft-shelled and rounded, resembling ping-pong balls, though some species lay brittle-shelled eggs. Clutch size varies significantly by species and individual, from one or two in smaller species to over 200 in larger ones like the Hawksbill sea turtle. Once laid, she covers the chamber with sand or soil, using her hind flippers to conceal the nest and regulate temperature. This covering process often involves camouflaging the nest by scattering sand widely before she returns to the water.
Inside the Egg and Hatching
Once laid, turtle eggs undergo embryonic development within the nest, a process spanning 45 to 75 days, though some species may take longer, up to 80 days or even 12 months in cases of embryonic diapause. Incubation is influenced by temperature, humidity, and the specific turtle species. A key aspect of turtle development is temperature-dependent sex determination (TSD), where nest temperature during incubation dictates hatchling sex. For most species, warmer temperatures produce more females, while cooler temperatures result in more males.
As the embryo matures, it absorbs nutrients from the yolk sac, growing into a hatchling. Hatching is a demanding process where the hatchling uses a temporary, pointed structure called a “caruncle” or “egg tooth” on its snout. This projection helps the hatchling cut or tear through the leathery eggshell. After breaking free, hatchlings collectively dig to the nest surface, a journey that can take several days.
Parental Care After Hatching
Turtles exhibit limited parental care beyond laying and burying their eggs. After the female covers the nest, her maternal duties are generally complete, and she returns to her habitat, leaving the eggs to incubate on their own. This means that newly hatched turtles are entirely independent from the moment they emerge from their nests.
Hatchlings must immediately navigate the challenges of their environment, including locating the ocean (for aquatic species) and evading predators. They instinctively head towards the brightest horizon, which is typically the open sea. This lack of post-hatching parental involvement is a common reproductive strategy among many reptile species.