Introduction Leeches are completely soft-bodied animals and could not be expected to leave a marked fossil record. Although there are two putative fossils from Bavarian deposits dating from the Upper Jurassic period (about 145 million years ago), Epitrachys rugosus (Ehlers, 1869) and Palaeohirudo eichstaettensis (Kozur, 1970). The evolutionary relationships of leeches demonstrate that the ancestral hirudinid was a blood feeder in a freshwater environment. This finding suggests that leeches are no older than vertebrates and probably no older than amphibians (Apakupakul et al., 1999).
Leeches are related to earthworms and lugworms (Oligochaetes), and bristle worms (Polychaetes). Leech is the common name for more than 300 species of annelid worms. Leeches belong to the class Hirudinea that prey on small invertebrates in fresh water or suck blood from vertebrate animals.
Every leech has muscular sucker at the rear end of the body; many have a second sucker around the mouth. These organs are used to assist a leech in the feeding process (Milne, 1987).
Leeches are external parasites (David Nichols and John Cooke, 1971). Leeches consume the blood of a wide variety of animal hosts, ranging from fish to humans (Godfrey, 1997). As predators, parasites of animals, vectors of parasites, and as food for semi - aquatic and aquatic animals, leeches are important components of food webs and leeches are also hermaphroditic but do not self-fertilize (Peckarsky et al., 1990).
Leeches are among the most poorly studied invertebrate taxa with respect to their evolutionary histories (Apathy, 1888; Selensky, 1915; Wendrowsky, 1928; Livanow, 1931; Autrum, 1939).The study of Leech is chosen because leeches have a unique body structure. Being a parasitic organism, leech brings a problem to the farmer and will slow down the growth of aquaculture especially during the reproductive period. My data can be used for further study.
Leeches are related to earthworms and lugworms (Oligochaetes), and bristle worms (Polychaetes). Leech is the common name for more than 300 species of annelid worms. Leeches belong to the class Hirudinea that prey on small invertebrates in fresh water or suck blood from vertebrate animals.
Every leech has muscular sucker at the rear end of the body; many have a second sucker around the mouth. These organs are used to assist a leech in the feeding process (Milne, 1987).
Leeches are external parasites (David Nichols and John Cooke, 1971). Leeches consume the blood of a wide variety of animal hosts, ranging from fish to humans (Godfrey, 1997). As predators, parasites of animals, vectors of parasites, and as food for semi - aquatic and aquatic animals, leeches are important components of food webs and leeches are also hermaphroditic but do not self-fertilize (Peckarsky et al., 1990).
Leeches are among the most poorly studied invertebrate taxa with respect to their evolutionary histories (Apathy, 1888; Selensky, 1915; Wendrowsky, 1928; Livanow, 1931; Autrum, 1939).The study of Leech is chosen because leeches have a unique body structure. Being a parasitic organism, leech brings a problem to the farmer and will slow down the growth of aquaculture especially during the reproductive period. My data can be used for further study.
Leech Taxanomy
Autrum (1936, 1939) was the first to summarize all pertinent publications on the taxonomic and phylogenetic relationships among the clitellates (Oligochaeta and Hirudinea). In general, the Clitellata can be defined as a monophyletic group of cylindrical (or disk-shaped) segmented invertebrates without parapodia that are characterized by a clitellum (Ax, 1999; McHugh, 2000). All Clitellata are hermaphrodites. They are comprised of two separate groups, the Oligochaeta (earth-worms and other non-carnivorous detritus feeders) and the Hirudinea (leeches, i. e., carnivorous predators or parasites).
The Euhirudinea or true leeches have been classified according to their mode of feeding as follows: Pharyngobdellida (pharynx unarmed, i. e., no jaws or a proboscis present), Gnathobdellida (oral sucker with jaws within the buccal cavity), and Rhynchobdellida (jawless pharynx; these worms utilize an evertible proboscis to penetrate the skin of their hosts). This scheme of classification (Autrum, 1939) has been used in the literature without many modifications (Mann, 1962; Herter, 1968).
The order Arhynchobdellida is comprised of leeches that are characterized by the lack of a proboscis: the non-sanguivorous (unarmed) Erpobdelliformes and the jawed (armed) Hirudiniformes.
Leech Habitat
Leeches (Hirudinea, Clitellata) are among the most numerous freshwater animals occurring in both standing and running waters (Scrimgeour et al., 1998). Most of the common leech species are classified as inhabitants of eutrophic, polysaprobic, moderately and highly stressed freshwater environments (Lenat, 1993). All of them use dissolved oxygen in respiration and have on easy-to-penetrate body surface (Neubert and Nesemann, 1999).
Autrum (1936, 1939) was the first to summarize all pertinent publications on the taxonomic and phylogenetic relationships among the clitellates (Oligochaeta and Hirudinea). In general, the Clitellata can be defined as a monophyletic group of cylindrical (or disk-shaped) segmented invertebrates without parapodia that are characterized by a clitellum (Ax, 1999; McHugh, 2000). All Clitellata are hermaphrodites. They are comprised of two separate groups, the Oligochaeta (earth-worms and other non-carnivorous detritus feeders) and the Hirudinea (leeches, i. e., carnivorous predators or parasites).
The Euhirudinea or true leeches have been classified according to their mode of feeding as follows: Pharyngobdellida (pharynx unarmed, i. e., no jaws or a proboscis present), Gnathobdellida (oral sucker with jaws within the buccal cavity), and Rhynchobdellida (jawless pharynx; these worms utilize an evertible proboscis to penetrate the skin of their hosts). This scheme of classification (Autrum, 1939) has been used in the literature without many modifications (Mann, 1962; Herter, 1968).
The order Arhynchobdellida is comprised of leeches that are characterized by the lack of a proboscis: the non-sanguivorous (unarmed) Erpobdelliformes and the jawed (armed) Hirudiniformes.
Leech Habitat
Leeches (Hirudinea, Clitellata) are among the most numerous freshwater animals occurring in both standing and running waters (Scrimgeour et al., 1998). Most of the common leech species are classified as inhabitants of eutrophic, polysaprobic, moderately and highly stressed freshwater environments (Lenat, 1993). All of them use dissolved oxygen in respiration and have on easy-to-penetrate body surface (Neubert and Nesemann, 1999).
Alkalinity is a requirement for leech survival with pH levels above 5.0 desired. The presence of dissolved oxygen is also required. Turbidity and salinity are thought to play small roles. Leeches have a high tolerance for pollution including eutrophication, oil, copper sulfate and pesticides. They have no tolerance, however, for zinc (Ginsberg, 1998). The factors which determine leech distribution in freshwater environments are, in approximate order of significance (Sawyer, 1986): availability of food organisms, nature of the substrate, depth of water, presence of water currents, size and nature of the body of water, hardness and pH, temperature of the water, dissolved oxygen, siltation and turbidity, and salinity.The single most important factor in a leech life is the presence of food. Leeches are limited by a very low pH, but otherwise the level of alkalinity does not have an effect on leech distribution. The medicinal leech is amphibious, needing both land and water, and resides exclusively in fresh water.
A typical habitat for H. medicinalis would be a small pond with a muddy bottom edged with reeds (Sawyer, 1986). It is found in warm, protected shallow areas of ponds with little wave action. It stays concealed during the day in dark places provided by vegetation, stones, and debris, and is most active at night (Moore, 1923).
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