Slugs and leeches do not have an outer skin that holds water inside of them. Thus, they require a moist environment to avoid drying out. If you put salt on them, the salt pulls the water out of their cells and kills them.
people and animals blood
Leeches and other blood sucking animals supposedly got rid of bad blood hope this helps
Leeches are known as parasites but they can be useful in medicine. After surgery, some doctors use leeches to prevent dangerous swelling near a wound. Also, leeches make a useful chemical that people can use.
It would be very unusual for leeches to kill people, however, they do suck blood, and a person can die from blood loss. In order to lose that much blood, a person would have to be unconscious will leeches are feasting at will.
People likely dislike leeches because they attach to skin and suck blood, causing discomfort or pain. Additionally, they can transmit diseases and infections, which adds to the negative perception of them.
Leeches suck blood and it was believed that leeches would actually suck the bad blood\diseased blood out of your body. Today leeches are used after reattachment of body parts, particularly fingers and toes. The leeches relieve the congestion of blood in the affected parts. The leeches also put a chemical into the blood in the area of the attachment that prevents blood from clotting.
leeches can suck blood clots out of people
they are used for people with high blood presure.
One way that leeches have helped in the prevention of heart is in the study of coagulation and the prevention of blood clots.
They proably leave because they hate people
People help animals (such as pets) which owners abandoned and/or could not afford to take care of their animals
Plants die, then animals die, then people die.