|
Leeches
Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodies that can lengthen and contract. Both groups are hermaphrodites and have a clitellum, but leeches typically differ from the oligochaetes in having suckers at both ends and ring markings that do not correspond with their internal segmentation. The body is muscular and relatively solid; the coelom, the spacious body cavity found in other annelids, is reduced to small channels. The majority of leeches live in freshwater habitats, while some species can be found in terrestrial or marine environments. The best-known species, such as the medicinal leech, ''Hirudo medicinalis'', are hematophagous, attaching themselves to a host with a sucker and feeding on blood, having first secreted the peptide hirudin to prevent the blood from clotting. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hirudo Medicinalis
''Hirudo medicinalis'', or the European medicinal leech, is one of several species of leeches used as medicinal leeches. Other species of ''Hirudo'' sometimes also used as medicinal leeches include ''Hirudo orientalis, H. orientalis'', ''Hirudo troctina, H. troctina'', and ''Hirudo verbana, H. verbana''. The Asian medicinal leech includes ''Hirudinaria manillensis'', and the North American medicinal leech is Macrobdella decora, ''Macrobdella decora''. Medicinal leech populations were reduced significantly in many countries during the 19th century due to the high demand in medical contexts, and remain endangered in many countries today. Morphology The general morphology (biology), morphology of medicinal leeches follows that of most other leeches. Fully mature adults can be up to 20 centimeters in length, and are green, brown, or greenish-brown with a darker tone on the Dorsum (biology), dorsal side and a lighter ventral side. The dorsal side also has a thin red stripe. These or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annelid
The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecologies – some in marine environments as distinct as tidal zones and hydrothermal vents, others in fresh water, and yet others in moist terrestrial environments. The annelids are bilaterally symmetrical, triploblastic, coelomate, invertebrate organisms. They also have parapodia for locomotion. Most textbooks still use the traditional division into polychaetes (almost all marine), oligochaetes (which include earthworms) and leech-like species. Cladistic research since 1997 has radically changed this scheme, viewing leeches as a sub-group of oligochaetes and oligochaetes as a sub-group of polychaetes. In addition, the Pogonophora, Echiura and Sipuncula, previously regarded as separate phyla, are now regarded as sub-grou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bloodletting
Bloodletting (or blood-letting) was the deliberate withdrawal of blood from a patient to prevent or cure illness and disease. Bloodletting, whether by a physician or by leeches, was based on an ancient system of medicine in which blood and other bodily fluids were regarded as "Humorism, humors" that had to remain in proper balance to maintain health. It was the most common medical practice performed by surgeons from Ancient history, antiquity until the late 19th century, a span of over 2,000 years. In Europe, the practice continued to be relatively common until the end of the 19th century.B.) Anderson, Julie, Emm Barnes, and Enna Shackleton. "The Art of Medicine: Over 2,000 Years of Images and Imagination [Hardcover]." The Art of Medicine: Over 2,000 Years of Images and Imagination: Julie Anderson, Emm Barnes, Emma Shackleton: : The Ilex Press Limited, 2013. The practice has now been abandoned by modern-style medicine for all except a few very specific medical condition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glossiphoniidae
Glossiphoniidae are a family of freshwater proboscis-bearing leeches. These leeches are generally flattened, and have a poorly defined anterior sucker. Most suck the blood of freshwater vertebrates like amphibians, crocodilians and aquatic turtles, but some feed on invertebrates like oligochaetes and freshwater snails instead. Although they prefer other hosts, blood-feeding species will opportunistically feed from humans. There is considerable interest in the symbiotic bacteria that at least some glossiphoniids house in specialized organs called bacteriomes. The bacteria are thought to provide the leeches with nutrients that are scarce or absent from their regular diets. '' Haementeria'' as well as '' Placobdelloides'' have Enterobacteriaceae symbionts, while '' Placobdella'' harbours peculiar and independently derived alphaproteobacteria. Systematics and taxonomy The relationships between members of Glossiphoniidae are not completely understood. Some sources divide the gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clitellum
The clitellum is a thickened glandular and non-segmented section of the body wall near the head in earthworms and leeches that secretes a viscid sac in which eggs are stored. It is located near the anterior end of the body, between the fourteenth and seventeenth segments. The number of the segments to where the clitellum begins and the number of segments that make up the clitellum are important for identifying earthworms. In microdrile earthworms, the clitellum has only one layer, resulting in a smaller quantity of eggs than that of the megadrile earthworms, which have larger multi-layered clitellum that have special cells that secrete albumin into the worms' egg sac. The clitellum is part of the reproductive system of clitellates, a subgroup of annelids which contains Oligochaeta, oligochaetes (earthworms) and Hirudinea, hirudineans (leeches). The clitellum is a thick, saddle-like ring found in the epidermis (skin) of the worm, usually with a light-colored pigment. To form a coco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hematophagous
Hematophagy (sometimes spelled haematophagy or hematophagia) is the practice by certain animals of feeding on blood (from the Greek words αἷμα ' "blood" and φαγεῖν ' "to eat"). Since blood is a fluid tissue rich in nutritious proteins and lipids that can be taken without great effort, hematophagy is a preferred form of feeding for many small animals, such as worms and arthropods. Some intestinal nematodes, such as Ancylostomatids, feed on blood extracted from the capillaries of the gut, and about 75 percent of all species of leeches (e.g., ''Hirudo medicinalis'') are hematophagous. The spider '' Evarcha culicivora'' feeds indirectly on vertebrate blood by specializing on blood-filled female mosquitoes as their preferred prey. Some fish, such as lampreys and candirus; mammals, especially vampire bats; and birds, including the vampire finch, Hood mockingbird, Tristan thrush, and oxpeckers, also practise hematophagy. Mechanism and evolution Hematophagous anim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hirudin
Hirudin is a naturally occurring peptide in the salivary glands of blood-sucking leeches (such as ''Hirudo medicinalis'') that has a blood anticoagulant property. This is essential for the leeches' habit of feeding on blood, since it keeps a host's blood flowing after the worm's initial puncture of the skin. Hirudin (MEROPS I14.001) belongs to a superfamily (MEROPS IM) of protease inhibitors that also includes haemadin (MEROPS I14.002) and antistasin (MEROPS I15). Structure During his years in Birmingham and Edinburgh, John Berry Haycraft had been actively engaged in research and published papers on the coagulation of blood, and in 1884, he discovered that the leech secreted a powerful anticoagulant, which he named hirudin, although it was not isolated until the 1950s, nor its structure fully determined until 1976. Full length hirudin is made up of 65 amino acids. These amino acids are organized into a compact N-terminal domain containing three disulfide bonds and a C-term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helobdella
''Helobdella'' is a genus of leeches in the family Glossiphoniidae, the freshwater jawless leeches. They occur worldwide.Kutschera, U., et al. (2013)Description of a new leech species from North America, ''Helobdella austinensis'' n. sp.(Hirudinea: Glossiphoniidae), with observations on its feeding behaviour.''Zoosyst Evol'' 89(2) 239-46. These are small, flat leeches which do not feed on blood.Siddall, M. E. and E. Borda. (2003)Phylogeny and revision of the leech genus ''Helobdella'' (Glossiphoniidae) based on mitochondrial gene sequences and morphological data and a special consideration of the ''triserialis'' complex.''Zoologica Scripta'' 32(1), 23-33. Several species in this genus are used as model organisms in the study of developmental biology. It has been difficult to define species in this genus without DNA analysis. Like other leeches in this family, some ''Helobdella'' species are polymorphic, coming in different colors and patterns. On the other hand, some uniformly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haemadipsa Zeylanica Japonica
''Haemadipsa'' is a genus of leeches, with members commonly known as ''jawed land leeches''. These annelids are known from subtropical and tropical regions around the Indian and Pacific Ocean. Well-known ''Haemadipsa'' are for example the Indian Leech (''Haemadipsa sylvestris'') and the yamabiru or Japanese Mountain Leech (''Haemadipsa zeylanica''). Members of the genus feed on blood. They are troublesome to humans and animals especially because their bites result in prolonged bleeding. Species in the genus ''Haemadipsa'' *'' Haemadipsa cavatuses'' *'' Haemadipsa cochiniana'' *'' Haemadipsa crenata'' *'' Haemadipsa hainana'' *'' Haemadipsa interrupta'' *'' Haemadipsa japonica'' *'' Haemadipsa limuna'' *'' Haemadipsa moorei'' *'' Haemadipsa montana'' *'' Haemadipsa ornata'' *'' Haemadipsa picta'' (Tiger leech) *'' Haemadipsa rjukjuana'' *'' Haemadipsa sumatrana'' *'' Haemadipsa sylvestris'' (Indian leech) *'' Haemadipsa trimaculosa'' *'' Haemadipsa zeylanica'' (Japanese mountain le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merriam-Webster
Merriam-Webster, Incorporated is an list of companies of the United States by state, American company that publishes reference work, reference books and is mostly known for Webster's Dictionary, its dictionaries. It is the oldest dictionary publisher in the United States. In 1831, George Merriam, George and Charles Merriam founded the company as G & C Merriam Co. in Springfield, Massachusetts. In 1843, after Noah Webster died, the company bought the rights to ''Webster's Dictionary#Noah Webster's American Dictionary of the English Language, An American Dictionary of the English Language'' from Webster's estate. All Merriam-Webster dictionaries trace their lineage to this source. In 1964, Encyclopædia Britannica, Inc., acquired Merriam-Webster, Inc., as a subsidiary. The company adopted its current name, Merriam-Webster, Incorporated, in 1982. History 19th century In 1806, Webster published his first dictionary, s:A Compendious Dictionary of the English Language, ''A Compen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greed
Greed (or avarice, ) is an insatiable desire for material gain (be it food, money, land, or animate/inanimate possessions) or social value, such as status or power. Nature of greed The initial motivation for (or purpose of) greed and actions associated with it may be the promotion of personal or family survival. It may at the same time be an intent to deny or obstruct competitors from potential means (for basic survival and comfort) or future opportunities; therefore being insidious or tyrannical and having a negative connotation. Alternately, the purpose could be defense or counteractive response to such obstructions being threatened by others. Modern economic thought frequently distinguishes ''greed'' from ''self-interest'', even in its earliest works, and spends considerable effort distinguishing the line between the two. By the mid-19th century – affected by the phenomenological ideas of Hegel – economic and political thinkers began to define greed inherent t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
