The origin and evolutionary history of turtles

Soft-shelled turtle, commonly known as "soft-shell turtle", "tuan fish", and "water fish" in Guangdong, is a wild reptile that inhabits rivers, lakes, and ponds. It likes to lurk at the bottom of the water during the day, and sometimes comes out of the water to breathe fresh air. In addition to preying on fish, shrimps, snails and clams in the water, it will also climb ashore to hunt for small animals such as earthworms. After it is full, it will dive to the bottom of the water. Because it often lives in the mud and sand at the bottom of the water, its body is often covered with moss and other attachments. Whenever it is sunny and warm, it will climb ashore to bask in the sun so that the dirt on its body can dry out and fall off. But it is extremely vigilant and will quickly escape back into the water as long as there is any noise nearby. Turtles have a long lifespan and can live for fifty or sixty years. However, they can lay eggs and reproduce offspring at the age of three or five.

When spring comes, the female turtle climbs ashore in the evening or early morning, chooses a relatively moist muddy ground, digs out a funnel-shaped cave with its front and rear paws, and lays eggs in the cave. There are 10 eggs laid at a time. The remaining ones, after laying eggs, refilled the caves with sand, and finally used their plastrons to flatten the ground before leaving safely. The soft-shell turtle has a long hibernation period. When the water temperature drops below 10 degrees Celsius, it basically cannot eat and enters a dormant state. This is also one of the reasons why it grows slowly.

Turtle meat is rich in nutrients, and people regard it as a good nourishing product. Turtle shells can also be used as medicine, so it is an aquatic product with high economic value. China generally regards soft-shelled turtles as a delicacy and as a nutritious food in diet. The history of eating turtles can be traced back to the Zhou Dynasty or even further. The soft-shelled turtle meat is delicious, and its skirt is especially popular. Soft-shell turtle is rich in protein, unsaturated fatty acids, polysaccharides, various trace elements and vitamins. The content of various nutrients varies depending on the part. Turtle meat is rich in animal glue, keratin, iron, vitamin D and other nutrients. Due to different types of meat and living areas, their nutritional content is not completely consistent.

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