The turtle that was the first to arrive (animal science knowledge)

There are seven major types of sea turtles in the world, and they all call the sea their home. But their ancestors lived on land. From the perspective of the evolutionary history of life, reptiles originated from amphibians and are distinguished from amphibians because they can lay amniotic eggs. Due to the production of amniotic eggs, animals can go to the hinterland of the land to thrive. Therefore, the earliest reptiles are called true terrestrial vertebrates precisely because they can live completely on land. Therefore, sea turtles must have evolved from early ancestors who lived on land. Turtles are known as vertebrates that descend to the sea.

Today's sea turtles live their entire lives in the sea. They are relatively large, reaching a length of more than 1 meter and weighing more than 100 kilograms. The largest ones can reach more than 2 meters and weigh 500 kilograms. The limbs have evolved from legs and feet adapted for terrestrial life to paddle-like flippers adapted for swimming, with the forelimbs being larger than the hind limbs. Unlike many terrestrial turtles, their heads and limbs cannot be retracted into their huge shells. Turtles also have particularly long diving abilities, and some can stay underwater for a day or night or longer.

Turtles are usually docile, but during the annual estrus period, they become very active and scramble to find their mates. April to June every year is the peak breeding season for sea turtles. Groups of sea turtles return to their hometown islands from thousands of miles away to lay eggs. Female turtles often follow the rising tide of the sea on calm, moonlit nights and climb onto the beach to find a suitable place to lay their eggs.

Turtles make long-distance round-trips along a certain return route every year, never losing their way. Even hatchlings that have never been outside can swim back to their original habitat along the same path that their mother took. According to expert research, this ability of sea turtles is controlled by the biological clock in the body of the sea turtle. It can swim according to the sun's position, correcting their heading with reference to ocean currents and water temperature. Scientists are working hard to explore this mystery in order to develop new navigation instruments based on its principles.

Turtles are found in my country from the Shandong coast in the north to the South China Sea islands in the south. The turtle's shell and fat can be used as medicine, and its blood and bile also have medicinal value. It is a precious protected animal and hunting is strictly prohibited.

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