leech, the application of a live leech to the skin to initiate blood flow or drain blood from a localized area of the body. Throughout the 19th century, leeches were often export into Europe, Asia, and the Americas to drain the body's blood supply, in a manner similar to blood flow. Today, however, leeches are used only occasionally to restore blood flow to damaged parts of a vein after reattaching an appendage or tissue graft. The type of leech most commonly used for this purpose is the European medicinal leech, Hirudo medicinalis, a segmented aquatic worm whose blood-sucking abilities once made it a valuable commodity. The medicinal leech has shown its usefulness in medicine because of its unique mouthparts and the pharmacologically active substances in its saliva. Hirudo medicinalis has three jaws with about 100 sharp teeth on each outer edge. The leech feeds by first placing its sucker on the skin. The mouth, located in the center of the cup, opens to expose the teeth, which cut through the patient's skin. Leech saliva contains substances that anesthetize the injured area (making the bite almost painless) and dilate blood vessels to increase blood flow to the sting site. Leech saliva also contains an enzyme that promotes the rapid removal of substances in the leech's saliva away from the sting site. One of these substances is hirudin, a natural polypeptide that inhibits the actions of thrombin, one of the enzymes that facilitate blood coagulation. This powerful anticoagulant, first identified in 1884 but not isolated in purified form until the 1950s, is primarily responsible for the extensive bleeding that results from a leech bite, although there are other factors. Hirudin is produced in commercial quantities using genetic engineering techniques. 
Hirudo medicinalis classification
The destruction Starting at the top with the broadest level of taxonomy, is the domain. Hirudio medicinalis classification belongs to the domain of eukarya, which means that the cells that make up the leech have a true nucleus and membrane-bound organelles. Most organisms familiar to humans belong to this group, including all animals, plants, and fungi. The next level of classification is the kingdom. Hirudo medicinalis belongs to the Animal Kingdom, which is characterized by heterotrophic, multicellular organisms without cell walls. In general, most animals have some form of mobility. They also lack plant characteristics such as chloroplasts and chlorophyll. Hirudo medicinalis belongs to the phylum annelida. Annelida comes from the Latin word, anellus, meaning "little ring." If you look closely at the leech, you will see these rings that join its body. Animals belonging to this phylum are marked by true segmentation, have three layers of tissue (triploblasitc), a true coelom, a closed circulatory system, and a straight digestive tract. Most people are probably familiar with one member of this phylum, the common earthworm. 
Annelids belonging to the class clitellata are characterized by the presence of a unique reproductive structure called the clitellum. The clitellum is a thickened part of the body wall that produces a cocoon sac around the eggs. Organisms in this class are usually all hermaphroditic and lack parapodia. The next level of classification is sequence. H. medicinalis belongs to the Arhynchobdellida. Members of this group are characterized by having a jaw-like structure at the anterior end of their body. More information on the special structures of H. medicinalis can be found in the adaptations section of this website. Leeches of the hirudae family are characterized by well-developed jaws with a row of sharp teeth. His pharynx is short and very muscular. They also have a lobed ceca crop.
- medicinalis belongs to the genus hirudo. Unlike other leech genera, members of the hirudo lack papillae (nipple-like structures) in their salivary glands.
- Also, the upper lip has no median ventral groove. The diameter of its posterior sucker is about 3/4 of the maximum body width.
Finally, we come to the species level of taxonomy. Hirudo medicinalis simply means medical leech, a very appropriate name as it is the most commonly used species in the environment. H. medicinalis is dark green in color, with orange lateral lines running down its back. 
Hirudo medicinalis life cycle
Hirudo medicinalis life cycle of leeches How do flatworms and roundworms reproduce? Leeches are segmented worms that live in a wide variety of environments, including freshwater, saltwater, and soil. They are hermaphrodites and produce young from eggs stored in cocoons. Some leeches are carnivorous, swallowing their prey whole, but most are parasitic, clinging to their hosts and moving around them with two suction disks attached to each end of their bodies. Blood-sucking leeches release anesthetic chemicals, anticoagulants, and antibiotics into their hosts so that the sting is not felt, blood flows freely, and infection is less likely. All leeches are hermaphrodites, meaning they each have male and female reproductive organs. However, they reproduce sexually, usually by joining their bodies. The male organ of a leech releases a spermatophore, or a capsule that encloses sperm, which then attaches to another leech. Once attached, the sperm exits the spermatophore and passes through the skin of another leech. Once inside, it travels to the ovaries and fertilizes the eggs. Eggs leeches in a jar Leeches make cocoons in which they lay their eggs. A leech releases its cocoon from glands; the cocoon is initially wrapped around the leech itself. When the cocoon slips off the leech's body, the fertilized eggs attach to the cocoon and mate with it. Leeches attach their cocoons to substrates such as rocks or plants. Leeches are segmented worms that live in a wide variety of environments, including freshwater, saltwater, and soil. They are hermaphrodites and produce young from eggs stored in cocoons. Some leeches are carnivorous, swallowing their prey whole, but most are parasitic, clinging to their hosts and moving around them with two suction disks attached to each end of their bodies. Blood-sucking leeches release anesthetic chemicals, anticoagulants, and antibiotics into their hosts so that the sting is not felt, blood flows freely, and infection is less likely. 
Reproduction The leeches met the water All leeches are hermaphrodites, meaning they each have male and female reproductive organs. However, they reproduce sexually, usually by joining their bodies. The male organ of a leech releases a spermatophore, or a capsule that encloses sperm, which then attaches to another leech. Once attached, the sperm exits the spermatophore and passes through the skin of another leech. Once inside, it travels to the ovaries and fertilizes the eggs. Eggs leeches in a jar Leeches make cocoons in which they lay their eggs. A leech releases its cocoon from glands; the cocoon is initially wrapped around the leech itself. When the cocoon slips off the leech's body, the fertilized eggs attach to the cocoon and mate with it. Leeches attach their cocoons to substrates such as rocks or plants. Presented by Science Often, there is a delay between fertilization and ovulation; in the case of one species of leech, up to 9 months may elapse between mating and emergence from the cocoon. In some species, the development of the eggs in the cocoon is as short as a week. In others, the development of the eggs takes longer and requires more parental care. Thin-walled cocoons, for example, require the leech that cares for them to cover them with its body until the eggs mature. Newly hatched leeches attach to the body of their caretaker, which they leave as soon as a suitable host is near and edible. After their first meal, they are completely independent.