''Microcotyle'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

which belongs to the

phylum In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature f ...

Platyhelminthes The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek language, Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a Phylum (biology), phylum of relati ...

and

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

Monogenea Monogeneans are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they have both male and female reprod ...

. Species of ''Microcotyle'' are

ectoparasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s that affect their host by attaching themselves as

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e on the gills of the

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

and grow into adult stage. This larval stage is called oncomiracidium, and is characterized as free swimming and

ciliated The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...

. Species of ''Microcotyle'' have only one host in their entire life cycle. 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

mariculture Mariculture or marine farming is a specialized branch of aquaculture (which includes freshwater aquaculture) involving the cultivation of marine organisms for food and other animal products, in enclosed sections of the open ocean ( offshore mari ...

d fish 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

Individuals of species of ''Microcotyle'', like any typical polyopisthocotylean

monogenea Monogeneans are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they have both male and female reprod ...

n, have an anterior organ called prohaptor, which is mainly used for feeding and attachment. Although the prohaptor is not the primary attachment organ, it is used to anchor the body of the parasite while the opisthaptor is being repositioned. The 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 The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struc ...

, followed by the

esophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...

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 posteriorly. The cruca is divided into pouches, which extend between vitellaria. Vitallaria are glands that secrete yolk around the egg. 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 The worms are hermaphroditic, containing both male and female organs. Each worm has reproductive organs such as vas deferens, testis,

uterus The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The uter ...

, vitelline duct,

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

, and

vitellaria ''Vitellaria paradoxa'' (formerly ''Butyrospermum parkii''), commonly known as shea tree, shi tree (), or vitellaria, is a tree of the family Sapotaceae. It is the only species in the genus ''Vitellaria'', They also have flame cells that function as a

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...

and remove waste material. 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.

Life Cycle

Species of ''Microcotyle'' have a direct life cycle; no intermediate hosts are needed to complete its life cycle. Marine fishes are the definitive host of these parasites. The adults live on the gill of the fishes as ectoparasites. The eggs are released into water, hatch and develop as oncomiracidium. The oncomiracidia, free swimming form larvae, move around and attach to another fish and grow into adult stage. The life cycle of species of ''Microcotyle'' is completed and repeated again and again.

Treatment

Bath treatment using praziquantel is the effective methods of treating ''Microcotyle sebastis'' on rockfish.Kim, Ki. H, and Jae. Cho. (2000). Treatment of ''Microcotyle sebastis'' (Monogenea: Polyopisthocotylea) infestation with praziquantel in an experimental cage simulating commercial rockfish ''Sebastes schlegeli'' culture conditions.. Diseases of Aquatic Organisms, Vol.40: 229-231, pp. 229–231 An experiment was done to indicate that feeding a praziquantel-adsorbed diet significantly reduces the abundance of ''M. sebastis'' infestation, and bathing in 100 ppm praziquantel for 4 minutes is effective for controlling ''M. sebastis'' infestation in a practical rockfish culture system.

Species

According to the World Register of Marine Species,WoRMS (2018). Microcotyle Van Beneden & Hesse, 1863. Accessed at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=119381 on 2018-11-29 there are more than one hundred species in this genus:

References

{{Taxonbar, from=Q5021745 Microcotylidae Monogenea genera