Trematoda Botulus microporus, a giant digenean parasite from the intestine of a lancetfish Scientific classification | Kingdom: | Animalia | Phylum: | Platyhelminthes Class: | Trematoda Rudolphi, 1808 Subclasses Aspidogastrea Digenea WikiDoc Resources for Trematoda Articles Most recent articles on Trematoda Most cited articles on Trematoda Review articles on Trematoda Articles on Trematoda in N Eng J Med, Lancet, BMJ Media Powerpoint slides on Trematoda Images of Trematoda Photos of Trematoda Podcasts & MP3s on Trematoda Videos on Trematoda Evidence Based Medicine Cochrane Collaboration on Trematoda Bandolier on Trematoda TRIP on Trematoda Clinical Trials Ongoing Trials on Trematoda at Clinical Trials.gov Trial results on Trematoda Clinical Trials on Trematoda at Google Guidelines / Policies / Govt US National Guidelines Clearinghouse on Trematoda NICE Guidance on Trematoda NHS PRODIGY Guidance FDA on Trematoda CDC on Trematoda Books Books on Trematoda News Trematoda in the news Be alerted to news on Trematoda News trends on Trematoda Commentary Blogs on Trematoda Definitions Definitions of Trematoda Patient Resources / Community Patient resources on Trematoda Discussion groups on Trematoda Patient Handouts on Trematoda Directions to Hospitals Treating Trematoda Risk calculators and risk factors for Trematoda Healthcare Provider Resources Symptoms of Trematoda Causes & Risk Factors for Trematoda Diagnostic studies for Trematoda Treatment of Trematoda Continuing Medical Education (CME) CME Programs on Trematoda International Trematoda en Espanol Trematoda en Francais Business Trematoda in the Marketplace Patents on Trematoda Experimental / Informatics List of terms related to Trematoda Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ## Contents * 1 Overview * 2 Taxonomy and biodiversity * 3 Etymology * 4 Life cycles * 5 References ## Overview[edit | edit source] The Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic worms, commonly referred to as flukes. ## Taxonomy and biodiversity[edit | edit source] The Trematoda are estimated to include 18 000[1] to 24 000[2] species, and are divided into two subclasses. Nearly all trematodes are parasites of molluscs and vertebrates. The smaller Aspidogastrea, comprising about 100 species, are obligate parasites of molluscs and may also infect turtles and fishes, including cartilaginous fishes. The Digenea, which constitute the majority of trematode diversity, are obligate parasites of both molluscs and vertebrates, but do not occur in cartilaginous fishes. Crepidostomum sp. do occur in Lake Sturgeon. Formerly the Monogenea were included in the Trematoda on the basis that these worms are also vermiform parasites, but modern phylogenetic studies have raised this group to the status of a sister class within the Platyhelminthes, along with the Cestoda. ## Etymology[edit | edit source] Trematodes are commonly referred to as flukes. This term can be traced back to the Saxon name for flounder, and refers to the flattened, rhomboidal shape of the worms. The flukes can be classified into two groups, on the basis of the system which they infect in the vertebrate host. Tissue flukes infect the bile ducts, lungs, or other biological tissues. This group includes the lung fluke, Paragonimus westermani, and the liver flukes, Clonorchis sinensis and Fasciola hepatica. Blood flukes inhabit the blood in some stages of their life cycle. Blood flukes include species of the genus Schistosoma. ## Life cycles[edit | edit source] All trematodes infect molluscs and most have a complex life cycle involving other hosts. Most trematodes are monoecious and alternately reproduce sexually and asexually. The two main exceptions to this are the Aspidogastrea, which have no asexual reproduction, and the schistosomes, which are dioecious. In the definitive host, in which sexual reproduction occurs, eggs are commonly shed along with host feces. Eggs shed in water release free-swimming larval forms that are infective to the intermediate host, in which asexual reproduction occurs. ## References[edit | edit source] 1. ↑ Cribb, T.H., R.A.Bray, D.T.J. Littlewood, S.P. Pichelin and E.A. Herniou. 2001. The Digenea in D.T.J. Littlewood and R.A. Bray, eds. Interrelationships of the Platyhelminthes pp 168-185. Taylor & Francis, London. 2. ↑ Poulin, R. and S. Morand. 2004. Parasite Biodiversity. Smithsonian Books, Washington. 216 pp. cs:Motolice de:Saugwürmer hr:Metilji it:Trematoda lv:Trematodes mk:Метили nl:Trematoda no:Ikter simple:Trematoda sk:Motolice sl:Sesači sr:Метиљ Template:WikiDoc Sources