Why does a silkworm have a needle-like thing growing on its tail?

The health status of the silkworm can be seen from the tail horn of the tail.

The small tip is the tail corner of the silkworm, which is the part that rises on the tail of the silkworm. According to the size, firmness and blackening of the tail horn, the health and maturity of the silkworm can be determined.

Strong tail horn, strong body and white body indicate that the silkworm is growing well, strong and well-raised, otherwise it is unhealthy, and the tail horn becomes black and the apex is zoomed, indicating that the silkworm is aging. soon.

Extended information: The tail horn seems to be a dispensable organ, but some studies say that the physiological function of the tail horn is mainly to balance the water pressure in the silkworm's body, so that the silkworm can... The water pressure remains the same before and after to facilitate the growth and development of silkworms.

In the larval stage, silkworms are relatively long. Surrounded by the body wall, the intestines, Malpighian ducts, trachea, nerves and other tissues are soaked in blood. In addition, the size of silkworms is? The head is slightly larger and the tail is slightly smaller. If there is no tail horn, then the fluid pressure on the tail of the silkworm will be greater than that on the chest. In order to solve this problem, the silkworm tail horn is not a dispensable thing?

In fact, the larvae of many insects have tail horns, and their functions are the same. The pressure inside the liquid depends on the height of the liquid surface. The erect tail angle changes the weak state of the silkworm's tail, keeping the liquid level at the silkworm's chest and tail at the same height, and maintaining the balance of water pressure in the silkworm's body.

Baidu Encyclopedia-Silkworm (Lepidoptera)