Out From the Sand
It's a starry night in August. A clutch of eggs lies hidden more than two feet below a sandy beach. The nest holds more than 100 eggs. Each egg is about the size of a golf ball. Inside each one, there may be a baby green sea turtle.
From the start, what happens to these turtles depends on the environment. The temperature of the sand determines whether sea turtles hatch as male or female. The sand here on Costa Rica's Tortuguero Beach is warm. So more of the hatchlings will be female.
One of the turtles begins to stir inside her shell. She tears at it with her caruncle. That's a sharp point on her beak. Still buried beneath the sand, she breaks free from her shell. Soon, the whole nest is alive with motion.
The baby turtle uses her flippers to climb up and up. It can take more than a day to reach the surface. She moves around, even stepping on top of her nest mates. Their movements help push sand toward the bottom of the nest. This gives the tiny turtles a boost to the top. All at once, the turtles free themselves from the sand.
The hatchling leaves the nest with many other baby turtles. She heads downhill, toward the horizon. That's where the sky and sea meet. She's drawn to the moonlight reflecting off the ocean. Luckily, there are no lights shining from a nearby street or house. These lights can confuse a baby turtle. They can make it to go the wrong way, away from the sea.
The hatchling's journey to the water is a race for survival. She is no bigger than a walnut. Crabs and night herons snatch up some of the other hatchlings on the beach. This young turtle makes it to the water.
The frothy surf pushes her back. She fights to swim against the breaking waves. Over and over, she dives under the waves, then comes up for air. Her swim continues through the first day and night. The young turtle will not slow down for two days.
Scientists know little about the next phase of a green sea turtle's life. This period is often called the "lost years." A couple days after leaving her nest, the little turtle may reach the open sea. The turtle's journey through the open ocean may last several years. She may move with the currents. Scientists think green sea turtle hatchlings float with mats of sargassum. This seaweed provides a hiding place as well as food.
The hatchling may snack on shrimp, small jellyfish and snails that drift in and around the seaweed. Unfortunately, the sea also contains plastic and trash that people throw away. Eating them could be a deadly mistake for the turtle.
There are many other dangers in the sea, too. Predators such as sharks swim below the small turtle. Large birds fly above. They might decide to make a meal of her.
The turtle gets some protection from the coloring of her shell. The bottom is almost white. Sharks swimming below may not spot her pale shell. It blends into the sunlit water. The top of her shell, or carapace, is dark. From above, the turtle blends into the dark water.
After several years pass, she is a juvenile. Her shell is about the size of a dinner plate. Soon it is time to leave the open ocean for coastal waters.
The sea turtle's new home is the warm waters along Floride's east coast. With her larger shell, she is safer in the near-shore waters than she was as a hatchling. Though she sometimes slurps up a jellyfish, she now eats mostly algae and sea grass.
The sea turtle slowly grows larger. Soon she moves to feeding grounds farther off shore where she grows into an adult. There, she eats a sea grass called turtle grass.
At night, the turtle rests in the water under rocks and ledges. She can hold her breath for up to five hours! Each day, she returns to graze on her plot of grass. She uses her sharp beak to tear and eat the young shoots.
Like a lawn mower, the turtle keeps the sea grass pastures cut short. This helps new grasses grow and keeps the pastures healthy. Eating sea grass and algae has turned her body fat a green color. In fact, this is how green sea turtles get their name!
When the turtle is about 26 years old, her shell is a meter (3.2 feet) long. She weighs around 136 kilograms (300 pounds). Now the adult turtle sets out on a new adventure.
She must return to the beach where she was born to lay her eggs. She begins her long trek back to Tortuguero. She may have to travel over 1,000 kilometers (621 miles) to get there.
Scientists are still learning how sea turtles find their way through the ocean. They think the turtles may sense changes in Earth's magnetic field. That may help the turtles create a kind of mental map. Their memory of chemicals or odors in the water also may help them find their way.
The turtle is well equipped for the journey. Her flippers are like wings. She flies through the water. Using her senses and strong flippers, she finds her way to Tortuguero. There, she finds a mate. A few weeks later, she climbs onto the beach. It is after dark when she arrives.
Out of the water, she struggles to move on land. She lumbers over the sand. She reaches a place where high tides will not wash away her eggs. Then she starts to dig.
She uses her front flippers to toss up sand. She shifts from side to side until she has a pit wider than her body. She uses her rear flippers to scoop out a smaller hole inside the pit. After two hours of hard work, she is ready to lay her eggs inside the smaller, deeper hole.
Her eggs fall into the deeper chamber, up to four at a time. She lays more than 100 leathery white eggs. She packs sand over them. Then she uses her flippers to toss sand to cover her nest.
In two weeks, the turtle will lay another clutch of eggs, and two weeks later, another. After about two months in the nests, new green sea turtles will hatch. They will begin their own journeys.
This sea turtle and her hatchlings face many threats. Not all of them are natural. People hunt and eat sea turtles and their eggs. Many sea turtles are injured by accident, caught in fishing nets or cut by boats' propellers. Turtles also are threatened by water pollution, including plastic and trash. Fortunately, many people are working to help sea turtles survive.
The Caribbean Conservation Corporation (CCC) works to protect sea turtles in Costa Rica and in other parts of the Caribbean. The group puts electronic tags on the turtles and uses satellites to track where they go. You can keep track of where the tagged sea turtles go, too!
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