Life Cycle of Sea Turtles

The adult female sea turtles that live, feed and rest year round in the open and near shore waters begin nesting on our beaches between May and August. The only reason these female turtles emerge from the ocean is to dig nests and lay eggs. The incubation period is about sixty days. After the tiny hatchlings emerge, usually between July and October, they trek to the ocean.

Male sea turtles spend their entire lives in the ocean, resting along reefs or on the water surface in the sun. Females need approximately 15 years to reach reproductive maturity, and will mate with several males to ensure genetic diversity within the population. Once seawater temperatures are around 78oF, typically in early May in southeast Florida, a female will crawl up the beach looking for a high and dry area of the sand, preferably at the dune line, to lay her eggs. After finding a nesting site, she will turn to face the Atlantic and, using her two hind flippers, dig an approximately 30-inch deep nest chamber and lay between 90 to 120 eggs. She will bury the eggs in the nest chamber, then turn and throw sand with her four flippers in an attempt to camouflage the nest site. The female turtle will then crawl back to the ocean, never to return to her nest.  An adult female sea turtle typically only lays eggs once every three years but in the nesting year can lay up to seven nests in one season.   

Newly laid eggs take approximately sixty days to incubate in the nest chamber. The incubation period may be longer if the sand is cooled by rain storms or shorter if the summer is dry and sand temperature is warm. The hatchling’s sex is determined by temperature variances in the nest chamber during incubation. A hatchling will be female if sand temperatures are warmer and male if sand temperatures are cooler.  This temperature-dependent sex determination skews population numbers. If a nest is in the shade, cooler temperatures may produce more males and vice versa. This is also a reason why sea turtle species populations are good indicators of climate change effects. Studies have shown that as ocean temperatures rise, the possibility exists that fewer to perhaps no males will be produced.   

At the end of the incubation period, all the eggs in one nest need about three days to hatch. The 90 to 120 hatchlings work together to explode, or emerge, from the nest and make their way to the ocean. The smell and sound of the ocean plus the reflective light from the moon and stars on the water’s surface guides the hatchlings to the Atlantic.

Only one out of one thousand sea turtle hatchlings survives to maturity. Thus the successful trek of each hatchling to the ocean is a key step in sustaining this species’ population.  




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