Green sea turtles are among the largest hard-shelled sea turtles, recognized by the greenish fat beneath their shells. These reptiles inhabit tropical and subtropical waters across the globe, including the Atlantic, Pacific, and Indian Oceans. They undertake extensive migratory journeys, often traveling thousands of miles between their foraging grounds and the specific beaches where they were born decades earlier. Classified as an endangered species, understanding their reproductive cycle, particularly their egg-laying behaviors, is important for conservation efforts.
Nesting Seasons and Frequency
The timing of green sea turtle nesting seasons varies geographically, influenced by regional environmental conditions. In the United States, nesting primarily occurs from June through late September. Caribbean populations typically nest between June and September, while in the Pacific, nesting can span from December to June, peaking in February. Green turtles in the Indian Ocean exhibit nesting year-round, though some populations prefer months like July to December.
Several environmental factors influence the precise timing of nesting. Warmer ocean temperatures can prompt turtles to begin their nesting activities earlier in the year. Additionally, lunar cycles play a role, with increased nesting activity often observed around the full moon. This may be related to higher tides, which can make accessing nesting beaches easier.
Female green sea turtles do not nest every year; instead, they typically return to their nesting beaches every two to five years. This interval allows them to replenish the energy reserves needed for reproduction. Within a single nesting season, a female lays multiple clutches, usually between one and nine, averaging two to five. Each subsequent clutch is typically laid approximately two weeks after the previous one.
The Nesting Process
Once ready to lay her eggs, a female green sea turtle emerges from the ocean, usually under the cover of night. She crawls onto the sandy beach, often selecting a site above the high tide line for her nest. The turtle then begins digging, first creating a large depression called a “body pit” using her powerful front flippers. They are known for creating particularly deep body pits.
After forming the body pit, she uses her smaller hind flippers to excavate a narrower, deeper egg chamber. This chamber extends straight down and widens at the bottom, its depth determined by the length of her stretched hind flipper. She then deposits her clutch of eggs into this chamber. A typical clutch contains an average of 110 eggs, though numbers range from 70 to over 200. These soft-shelled eggs resemble ping-pong balls.
Upon completing egg deposition, the female covers the eggs by sweeping sand back into the chamber with her hind flippers. She then camouflages the nest, using her front flippers to throw sand backward over a wide area. This creates a large, disturbed mound, disguising the eggs, often three to four feet below the surface.
The entire nesting process, from emergence to returning to the sea, can take 1.5 to 3 hours. During this time, the female is vulnerable, emphasizing the need for undisturbed sites.
Hatching and Hatchling Emergence
After the eggs are laid, they undergo an incubation period lasting 50 to 70 days, typically 60 days, depending on environmental conditions. Nest temperature plays a significant role in embryo development, determining hatchling sex; cooler temperatures produce more males, while warmer temperatures result in more females.
Once development is complete, hatchlings break free from their shells using a temporary pointy growth on their snout called a caruncle. They then begin a coordinated ascent, digging to the sand surface, a process that can take three to seven days. Hatchlings communicate through sounds within the nest to synchronize emergence, ensuring they all break out together.
This mass emergence typically occurs at night, helping them avoid intense daytime heat and reducing exposure to visual predators. Upon reaching the surface, hatchlings enter a “frenzy” of activity, instinctively orienting toward the brightest horizon, usually the reflection of the moon and stars on the ocean.
This frantic dash to the water helps them quickly escape the beach, where they face numerous threats from predators such as birds, crabs, and fish. Light pollution from coastal development can disorient them, drawing them away from the ocean and reducing survival chances. Only about 1 in 1,000 to 1 in 10,000 green sea turtle hatchlings survive to adulthood. Once in the water, many hatchlings enter a period known as the “lost years,” swimming to offshore areas and often finding shelter and food within floating mats of seaweed, such as Sargassum.