Fossil records have shown that turtles have been swimming in the oceans around 100 million years and before dinosaurs existed. There are seven species of marine turtles in the world's oceans which include the flatback turtle, green turtle, loggerhead turtle, Olive Ridley, leatherback, hawksbill turtle, and Kemps Ridley.
Turtles are large air-breathing animals in the reptile family. They have scaly skin and depend on external temperatures to regulate body temperatures just like other reptiles. Turtles give birth by laying eggs, but they do not have gills like fish. They need to rise to the surface of the water to take a breath of air. They only need to do this every 15 to 20 minutes while feeding, but only once every 30 minutes when sleeping. Unlike mammals, baby turtles are on their own from the time the eggs are laid.
Female turtles dig nests on sandy beaches searching for the right place to lay their eggs. They lay between 60 and 120 eggs, and depending on the species, they take about 8 to 12 weeks to hatch. When the young hatch, they wait under the surface of the sand until night, so they can run to the ocean avoiding the predators as best as possible and during cooler temperatures. They are at less risk of dehydration. Unfortunately, only about one out of one-thousand hatchlings survive to become an adult.
Crawling together to the sea, the hatchlings swim for several days where the ocean currents will take them far away. They may drift for several years surviving on seaweed and other small plants and animals. Little is known about their time at sea, and scientists call it the 'lost years'. At some point, between the ages of 5 and 15, they leave the open seas and head for a coastal feeding ground.
When the marine turtles are about 30 or 40 years old, they will begin to have offspring of their own. When ready, they head back to the beach or nearby in the same area where they were hatched many years earlier. The migration can be over a thousand miles until they reach their breeding and nesting sites. Scientists believe they find their way by reading the Earth's magnetic field, ocean currents, and the sun's angle.
When breeding, most of the females will mate with many different males anywhere from where they find food to where they are going to nest. They wait until the cool of the night to climb onto the beach in search of a nesting site. Once the female has laid her eggs, she will make the long and dangerous swim back to her feeding areas. The female turtle will lay 3 to 7 nests in one season but will only breed every few years.
Finally, turtles have front and back flippers. The front flippers are very strong and are used for swimming, and the back flippers are used for steering and digging nests in the sand. Their hearing and sight are very good when underwater, but not so much when above water. Turtles drink the water they swim in, but fortunately, there are salt glands behind their eyes that remove salt from the water. When being used, the glands could make it look like the turtle is crying.
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