|
''Microcotyle'' is a genus which belongs to the phylum Platyhelminthes and class Monogenea. It is an ectoparasite that affects its host by attaching itself as a larva on the gills of the fish and grows into adult stage. This larval stage of ''Microcotyle'' is called oncomiracidium, and is characterized as free swimming and ciliated. ''Microcotyle'' is considered as a monogenetic parasite, having only one host in its entire life cycle. However, different species of ''Microcotyle'' inhabit marine and freshwater and they can also infect different species of fishes. They are uniquely characterized by their haptor having a lot of tiny clamps on the lateral margins. Although not really known to cause that much damage in marine wildlife, some of them are reported to cause agricultural problems like ''Microcotyle sebastis'' as an example. ''Microcotyle sebastis'' commonly affects ''Sebastes schlegeli'', a farm fish found in Korea.〔Kim, Ki. H, and Eun. Lee, and Se. Kwon, and Jae. Cho. (2001). Treatment of ''Microcotyle sebastis'' infestation in cultured rockfish Sebastes schlegeli by oral administration of praziquantel in combination with cimetidine. Diseases of Aquatic Organisms, 44 (2), pp. 133–136〕 ==Morphology == ''Microcotyle'', like any typical polyopisthocotylean monogenean, has an anterior organ called prohaptor, which is mainly used for feeding and attachment. Although prohaptor is not the primary attachment organ, it is used to anchor the body of the parasite while the opisthaptor is being repositioned. Opisthaptor is found in all ''Microcotyle'' species and it is an important attachment organ that allows these ectoparasites to latch onto their hosts. Located at the anterior part of the worm is the funnel-shaped mouth that is connected to the pharynx, followed by the esophagus that is smaller in diameter compared to the pharynx. About one tenth of the entire length of the worm, the esophagus then divides into intestinal crura, which extends further end to the genital hooks. The cruca is divided into pouches, which extend between vitallaria. Vitallaria is a group of glands of intervebrates that secrete yolk around the egg that does not contain yolk. This digestive pathway is observed to be continuous throughout the entire worm. Food particles were observed to be passing back and forth along these pathways in vivo.〔Remley, L. W. 1942. Morphology and Life History Studies of ''Microcotyle spinicirrus'' MacCallum 1918, a Monogenetic Trematode Parasitic on the Gills of ''Aplodinotus grunniens''. Transactions of the American Microscopical Society, Vol. 61, No. 2 (Apr., 1942), pp141–155〕 ''Microcotyle'' is hermaphroditic, containing both male and female organs. Each worm has reproductive organs such as vas deferens, testis, uterus, vitelline duct, ovary, and vitellaria. Vitelline duct is a passageway for excretions or secretions while vitellaria is responsible in secreting yolks around the egg.〔Remley, L. W. 1942. Morphology and Life History Studies of ''Microcotyle spinicirrus'' MacCallum 1918, aMonogenetic Trematode Parasitic on the Gills of ''Aplodinotus grunniens''. Transactions of the American Microscopical Society, Vol. 61, No. 2 (Apr., 1942), pp141–155〕 ''Microcotyle'' also has flame cells that function as a kidney and remove waste material. However, these flame cells are concealed by the vitellaria. A short duct that opens to the outside on the dorsal surface is composed of, four canals on each side, two posterior and two anterior, that come together laterally to the cirrus. During observation on immature specimens, these canals can still be seen. However, on adults, these canals are concealed by vitellaria.〔Remley, L. W. 1942. Morphology and Life History Studies of Microcotyle spinicirrus MacCallum 1918, aMonogenetic Trematode Parasitic on the Gills of Aplodinotus grunniens. Transactions of the American Microscopical Society, Vol. 61, No. 2 (Apr., 1942), pp141–155〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Microcotyle」の詳細全文を読む スポンサード リンク
|