What kind of bug is this?

Leech, also known as leech, is an annelid animal with earthworm in animal classification. Leech is a famous "vampire" in the mountain forest, and often inhabits the humid mountain grassland or bamboo forest in southern China.

Leech's body is divided into 27 sections, with a sucker at the head and a sucker at the tail. The center of the front sucker is a mouth, in which there are three meat jaws in a Y shape, and a row of small teeth are arranged on the longitudinal ridge of each meat jaw. When people or animals walk in the mountains, leeches will unconsciously climb on their legs and seize the opportunity to block the road and rob. It firmly sucks the skin with two suction cups, and then cuts the wound of "Y" on the skin with the jaw in its mouth to suck blood. Because leeches can secrete anticoagulant substances in the mouth and destroy the coagulation function of platelets in the blood, wounds bitten by leeches often bleed. In hospitals, doctors often use this feature to treat patients with local congestion with leeches or other leeches.

In addition, there are hirudins living in water, such as blood-sucking medical leeches and cattle leeches, nasal leeches parasitic in the respiratory tract of people and animals, fish leeches that harm fish and so on. Although leeches are not a good thing, they can accurately predict the weather because they are very sensitive to hypoxia in water. Before the rain, the air pressure was low, the humidity was high, and there was no oxygen in the water, so it was very difficult for leeches to breathe, so they fidgeted and rolled up and down in the water, indicating that a storm was coming.