Sea turtles are marine reptiles whose life cycle includes a period when hatchlings emerge from nests on sandy beaches. This emergence is crucial for their survival, marking the beginning of a challenging existence as these tiny creatures face obstacles from the moment they leave their underground nests.
Global Hatching Seasons
Sea turtle hatching months vary across the globe and by species, depending on nesting seasons and local climates. In the Northern Hemisphere, nesting occurs during warmer months, with hatching following a few months later.
In the United States, particularly Florida, nesting seasons generally run from March through October, meaning hatchlings emerge from May through December. Loggerhead turtles, common in Florida, nest from April to September, with hatchlings appearing from July to October. Green turtles in the U.S. nest from June to September, hatching approximately two months later. Leatherback nesting in the U.S. and Caribbean occurs from March to July, with eggs incubating for about two months.
In regions like the Riviera Maya, Mexico, sea turtles nest from June to November, with hatching from August to January. Barbados experiences year-round nesting, with peak hatching for hawksbills from June to December and for leatherbacks from April to September. In Costa Rica, green sea turtles peak nesting and hatching from July to October, while leatherbacks nest and hatch between March and May on the Caribbean coast and September to March on the Pacific coast. The Maldives sees nesting and hatching throughout the year, with July to August being the busiest hatching period.
The Hatching Process
The process of sea turtle hatchlings emerging from their eggs and the nest is a coordinated effort. Inside the egg, a hatchling uses a temporary egg tooth, called a “caruncle,” to break through its shell in a process known as pipping. This breaking free from the eggshell can take up to three days.
Once out of their shells, hatchlings do not immediately leave the nest. Instead, they work together, digging their way to the surface. This cooperative digging can take several days, from three to seven days, as they ascend through the sand chamber. Hatchlings emerge from the nest at night, influenced by cooler sand temperatures, which helps them avoid daytime predators and extreme heat.
Influences on Hatching Time
Environmental factors influence incubation duration and hatching time for sea turtles. Sand temperature is a primary determinant, as warmer sand leads to faster incubation periods. Incubation times for most species range from 45 to 70 days, though this can extend from 40 to 80 days depending on region and conditions. In the Maldives, incubation periods range from 49 to 62 days, while in colder regions, it can extend to 80 days.
Sand temperature also determines the sex of hatchlings, a phenomenon called Temperature-Dependent Sex Determination (TSD). Warmer temperatures produce more female hatchlings, while cooler temperatures result in more males. A nest incubated above 31°C (87.8°F) can produce almost all females, while temperatures below 27.7°C (81.86°F) can yield mostly males. Nest depth, humidity, and rainfall can also affect incubation duration.
Life After the Nest
Upon emerging from the nest, sea turtle hatchlings journey toward the ocean. Their survival depends on quickly reaching the water and swimming to offshore areas. Hatchlings instinctively orient towards the brightest horizon, typically the night sky reflected by the ocean. They rely on this natural light cue to navigate, moving away from dark silhouettes of dunes or vegetation.
This dash from the nest to the sea is dangerous, as hatchlings are vulnerable to predators, including birds, crabs, and fish once they enter the water. To increase their chances of survival, hatchlings often emerge en masse, overwhelming predators. Once in the water, a “swim frenzy” of continuous swimming for 24 to 48 hours helps them reach deeper waters, where they are less susceptible to predation.