![]() ![]() ![]() 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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