How to tell whether a crab is male or female?

Speaking of? How to distinguish between male and female Yangcheng Lake hairy crabs? The answer is already well known, the simplest and most direct way is to look at the crab belly. If the belly button is pointed and triangular, it is a male crab; if the belly button is round, it is a female crab. So where did the saying that Yangcheng Lake hairy crabs are distinguished by their sharp navel and round navel originate?

Then, the editor of ?Su Xie Ge looked through major dictionaries, and the general explanation was as follows.

Quoting scriptures:

From a passage in "Piya" written by Lu Dian of the Song Dynasty: "Crabs are water bugs with hard and brittle shells. Those with round navel are female, and those with pointed navel are male." ; The umbilicus is the female crab, and the tip is the male crab.

Everyone must know that Yangcheng Lake hairy crabs have tails when they are larvae. The tail keeps stretching, bending and flicking, so that the body can swim freely and look for food everywhere. It is a bit like a tadpole. .

After that, the larvae molt into young crabs, and the little tail naturally sticks to the belly of the body. At first, the young crabs are all long and narrow. Later, in the mature stage, the navel of the female gradually turns into a round (round umbilicus), while the navel of the male becomes a long and narrow triangle (pointed umbilicus). Over time, people passed it down orally, and there was a saying that "the umbilicus and the pointed umbilicus have become the most obvious signs for identifying the male and female Yangcheng Lake hairy crabs."

In fact, the navel of Yangcheng Lake hairy crabs was not called "pointed navel and round navel" in the early days, but was called "mantis ant and broad belt". Forgive me, editor, for my limited talent and limited knowledge of reading. I can’t even pronounce the word “mantis ant”! Popularize "mantis ant" and pronounce it as "láng yǐ".

Quoting scriptures:

As early as the Wei Dynasty of the Three Kingdoms, it was pointed out in Zhang Yi's "Guang Ya": "The male is called the mantis ant, and the female is called Bodai."

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So there may be the name "Mantis Ant and Bodai", but the actual origin, basis and reason for the name have been unclear for a long time. However, the undeniable fact is that "the male and female Yangcheng Lake hairy crabs have been distinguished by this method for nearly two thousand years." Perhaps because the names "Mantis ant and Bodai" were too weird and difficult to describe vividly, intuitively and popularly, they were passed down from word of mouth. Later, they were replaced by the easy-to-understand names "Pointed navel and Tuan navel", thus gaining more popularity. The number of people, the larger range and the higher frequency of communication.