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Life Cycle of Leatherback Turtles

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The leatherback sea turtle's inky-blue carapace is flexible and leathery, and it has lengthwise ridges. He's the largest turtle in the world, reaching 7 feet long and weighing 2,000 pounds or more. Unlike most reptiles, the leatherback (Dermochelys coriacea) is warm-blooded. His ancestors inhabited the seas more than 100 million years ago. An essential link in marine ecosystems, the leatherback population is declining in the Pacific Ocean, although their numbers are stable, or possibly increasing, in the Atlantic Ocean.

Mating Habits

Leatherback turtles journey to their birthplaces to mate, sometimes migrating over 1,000 miles. Copulation occurs offshore during fall and winter, each female mating with several males. Males spend their entire lives in the ocean; females roam the ocean until they reach sexual maturity, between the ages of 13 and 14, and go on land only to lay their eggs. Females tend to go ashore in groups during the nesting period.

The Nest

The female leatherback turtle digs a pit in the sand, above the shore-line, depositing approximately 80 eggs into the nesting chamber. She covers the nest with moist sand and returns to the ocean. The female lays up to seven clutches in a season, often not mating again for a few years. The temperature inside the nesting chamber determines the sex of the hatchlings. A temperature of 85.1 degrees Fahrenheit will result in both male and female hatchlings. Higher temperatures produce female offspring, while lower temperatures produce males.

From Hatchlings to Adults

Leatherback turtle eggs begin hatching in seven to 12 weeks. The hatchlings wait just under the sand's surface, and when a temperature drop occurs at nightfall, they all emerge together. The tiny turtles follow the lowest light on the horizon, scurrying for the ocean. Hatchlings, juveniles and adults share coastal feeding areas, where jellyfish are plentiful. Leatherback turtles can live up to 50 years, but only one in every 1,000 hatchlings will reach adulthood.

Predators and Threats

Seabirds, dogs, raccoons, skunks, opossums and crabs eat leatherback turtle eggs and hatchlings. Sharks will eat hatchlings and adults. Humans may be the leatherback turtle's worst enemy. Humans over-harvest turtle eggs for aphrodisiacs and food. Leatherbacks become entangled in fishing lines and nets, and are cut by boat propellers. Leatherbacks mistake floating pieces of discarded plastics for jellyfish and consume them, often resulting in death. Coastal development and depletion of jellyfish populations are other factors in the turtle's declining numbers.