All turtle species, whether living primarily in water or on land, reproduce by laying eggs. They do not give birth to live young, making egg-laying a universal aspect of their life cycle.
The Nesting Ritual
Female turtles must return to land to lay their eggs, even aquatic species. They seek out nesting sites with soft soil or sand that receives ample sunlight, such as riverbanks or beaches. The female begins by using her front flippers to create a body pit, a shallow depression for positioning herself. She then digs a flask-shaped egg chamber using her hind limbs, scooping out sand alternately with each foot until the cavity is deep enough. This chamber can be over a foot deep, with some sea turtle nests reaching up to two feet.
Once the nest is prepared, the female begins to deposit her eggs, usually two or three at a time. The number of eggs, known as a clutch, varies significantly by species and size, ranging from a few to over a hundred. Turtle eggs differ from bird eggs; they are typically spherical or slightly oval and have soft, leathery shells, though some species lay hard-shelled eggs. This flexibility allows the eggs to absorb moisture and withstand the drop into the nest without breaking.
After all eggs are laid, the female covers them using her hind flippers to scoop and compact the sand. She then often uses her front flippers to scatter sand over a wide area, camouflaging the nest and obscuring her tracks to deter predators. This entire nesting process can take several hours, after which the female returns to the water, leaving the eggs to develop.
From Egg to Independent Hatchling
After the eggs are laid and covered, they undergo an incubation period, which varies by species and environmental factors such as temperature and humidity. Incubation typically ranges from 45 to 75 days, though it can extend up to 12 months. Temperature plays a significant role in determining the sex of the hatchlings for most turtle species. This phenomenon, known as temperature-dependent sex determination (TSD), means that cooler nest temperatures often produce more males, while warmer temperatures result in more females.
When ready to hatch, the tiny turtles use a specialized, temporary structure called a caruncle, or “egg tooth,” located on the tip of their snout. This keratinous bump is not a true tooth but a tool to break through the eggshell from the inside. Hatchlings repeatedly tap and chip away at the shell, a process known as “pipping,” until they create an opening large enough to emerge.
After breaking free from their individual shells, hatchlings may take several days, typically 3 to 7, to dig their way out of the nest chamber and reach the surface. They often emerge at night to reduce exposure to predators. Once out of the nest, turtle hatchlings are entirely independent, with no parental care from the mother. They instinctively navigate to water and begin their solitary lives.