How Sea Turtles Hatch: A Nest That Boils, and a Race to the Sea

Sea turtle hatchlings leave their nest all at once, and there is a reason. By emerging together and rushing to the sea in a crowd, they overwhelm the predators waiting for them — and give more of themselves a chance to survive.

The mother's return

In summer, when the weather is warm, pregnant female sea turtles return to the beaches where they hatched years before. Each swims through the surf, crawls up the beach to find a spot above the high-water mark, and digs a nest in the sand with her back flippers. Digging and laying usually take one to three hours; then she slowly drags herself back to the ocean.

Eggs, and the sand's decision

A sea turtle lays up to 100 eggs, which incubate in the warm sand for about 60 days. The sand's temperature decides whether the babies are male or female: cooler sand produces more males, warmer sand more females. This is called temperature-dependent sex determination (TSD), and it also governs other reptiles such as alligators and crocodiles. NOAA research suggests that warming from climate change may lead to more female sea turtles, which could affect genetic diversity.

The "turtle boil"

The hatchlings emerge almost in unison, so the sandy nest looks like a pot of boiling water — in some places these events are called "turtle boils." They find the ocean by following the downward slope of the beach and the reflections of the moon and stars on the water.

The gauntlet

Sea birds, foxes, raccoons and wild dogs wait along the way. Hatching and running together helps the hatchlings overwhelm them. Those that make it swim out to floating mats of sargassum, where they spend their early years mostly hiding and growing.

Nesting sea turtles and hatchlings are protected by law on all U.S. shores, so keep your distance.

Sources

Based on "How do sea turtles hatch?" from NOAA's National Ocean Service, a work of the United States government in the public domain.