5/26/2023 0 Comments Freshwater leech identification![]() Around 1850 this practice fell into disrepute, but H. The medicinal leech, as its name suggests, has historically been used for medicinal purposes, mainly to remove "bad blood" from the diseased. Young leeches feed on frogs instead of mammals because their jaws are not yet strong enough to cut through mammalian skin (Grzimek, 1974 Sawyer, 1986). medicinalis may even go longer than six months without food by digesting its own tissues. Certain bacteria keep the blood from decaying during the long digestion period. Leeches only feed about once every six months, this is about how long the blood meal takes to be fully digested. After a full meal of 10ml to 15 ml of blood, the medicinal leech may increase 8 to 11 times its initial body size. It has three jaws, which work back and forth during the feeding process, which ususally lasts about 20 to 40 minutes and leaves a tripartite star-shaped scar on the host. Simultaneously, the leech injects an anaesthetic so that its presence is not detected, and an anticoagulant in order for the incision to remain open during the meal. It attaches to the host by means of its two suckers and bites through the skin of its victim. Hirudo medicinalis is parasitic and the adults feed on the blood of mammals. It becomes desensitized during feeding and copulation to the point where its posterior end can be cut off and it will continue the same behavior (Grzimek, 1974 Sawyer 1986). The leech is sensitive to light, heat and dessication. A dark shadow may also set off an alarm response in the leech in which it halts ventilation. medicinalis will respond to moving shadows, which often indiciate a source of mammalian food. The leech is able to detect the movement of shadows above. While at rest, the medicinal leech lies under large objects on the shoreline, partially out of water. They attach themselves to the substrate alternately by their anterior and posterior suckers. Movement on land is accomplished by means of "looping", a movement similar to that of inch worms. Hirudo medicinalis moves in water by contraction of the longitudinal muscles of the body in a wave-like motion which propels it forward in the water. Motility is achieved both in land and water. After about 14 days, the eggs hatch as fully formed miniature adults (Grzimek, 1974 Sawyer 1986). The whole egg sac is laid in damp soil usually just above the shoreline. A cocoon is formed around the clitellum and slips off the anterior section of the leech. ![]() Sperm is injected into the vagina by an extendable copulatory organ. All leeches are hermaphroditic and fertilization is internal. The act of copulation takes place on land, where one leech attaches ventrally to one another by means of a mucus secretion. It also remains fertile over a period of years,unlike most other leech species. medicinalis breeds once during an annual season that spans June through August. medicinalis has several pairs of testes and one pair of ovaries as well as a thickening of the body ring, known as a clitellum, which is visible during the breeding season (Grzimek, 1974). In addition, the medicinal leech has five pairs of eyes located on its front end. The anterior sucker surrounds the oral opening where the teeth for incison are located. All members bear a posterior and anterior disk-shaped sucker. The dorsal side is dark brown to black, bearing six longitudinal, reddish or brown stripes, and the ventral surface is speckled. The medicinal leech has a cylindrical, dorsoventrally flattened body divided into thirty-three or thirty-four segments. medicinalis would be a small pond with a muddy bottom edged with reeds and in which frogs are at least seasonally abundant (Sawyer, 1986). The medicinal leech is amphibious, needing both land and water, and resides exclusively in fresh water. The range extends through parts of western and southern Europe to the Ural mountains and the countries bordering the northeastern Mediterranean (Sawyer, 1986). ![]()
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