Leech, also called bloodsucker, is a worm that has a disklike sucker at each end. It has a mouth centered in the front sucker, and may also have small teeth. Some leeches live as parasites, sucking on the blood and tissue of other animals for nourishment. Others feed on decaying animal and plant material. Parasitic leeches attach to their victim with the front sucker, make a wound, and then suck out blood. Bloodsucking leeches produce a liquid containing a chemical substance called hirudin. Hirudin prevents the blood from thickening and makes it easier for the leech to suck the blood.
Doctors once commonly used what they called medicinal leeches to remove blood in the treatment of many illnesses. Today, doctors occasionally use leeches to reduce the accumulation of blood in tissues after plastic surgery and after severed fingers or hands have been surgically reattached.
A leech’s body is made up of a series of ringlike segments (parts). Leeches may be from 3/4 to 8 inches (2 to 20 centimeters) long and can stretch or shorten their bodies. They are black, red, or brown and may have stripes or spots. They have clusters of light-sensitive cells called “eyes” near the front end. They are also sensitive to touch, temperature, and drying. A leech contains both male and female reproductive organs.
Leeches live in damp places, such as the moist soil or vegetation of jungles. They are also found in the shallow water of streams, lakes, or oceans.
