Leatherbacks are the biggest sea turtles on Earth, with some weighing in at more than 2,000 pounds (907 kilograms). "They can be the size of your kitchen table," says Lisa Bailey of Conservation International. They're also ancient—leatherbacks have lived on Earth for about 100 million years.
But today they're in trouble. At sea, turtles can get tangled in fishing nets or suffocate on drifting plastic bags, which they mistake for jellyfish. On the beach, bright lights from hotels and houses sometimes confuse both adult females coming ashore to lay their eggs and hatchlings trying to find their way to the ocean.
These and other problems have caused Pacific leatherback sea turtle populations to drop by 90 percent over the past 20 years. "If we don't do something, they'll be gone in ten years," said Bullis Charter School student Talliya Smith, 11. Smith helped release hatchlings and excavate leatherback nests with her classmates at Playa Grande in Costa Rica.
The migrating leatherbacks swim more than 750 miles (1,207 kilometers) south to the waters around the Galápagos. Some go even farther south to the colder waters off Chile. Cruising at a rate of more than 43 miles (70 kilometers) per day, they make the trip in about two or three weeks. Once they arrive, the turtles dive to depths of more than 3,280 feet (1,000 meters) in search of jellyfish and other food. In four years, when the turtles are ready to nest again, they'll return to Costa Rica, says sea turtle expert James Spotila.
Source :http://kids.nationalgeographic.com
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