Diplozoon paradoxum Freshwater fish that become infected with this parasite become lethargic and end up swimming towards the surface of the water. In addition, some may be seen rubbing the bottom or sides of their skin where the parasite is located. Infected skin where the parasite is attached may show areas of scale loss and may produce a pinkish fluid. Gills that are infected may appear swollen and pale.
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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 reproductive structures. Some monogeneans are oviparous egg-laying and some are viviparous live-bearing. Oviparous varieties release eggs into the water. Viviparous varieties release larvae, which immediately attach to another host. The genus Gyrodactylus is an example of a viviparous variety, while the genus Dactylogyrus is an example of an oviparous variety.
Freshwater fish that become infected with this parasite become lethargic and end up swimming towards the surface of the water. In addition, some may be seen rubbing the bottom or sides of their skin where the parasite is located. Infected skin where the parasite is attached may show areas of scale loss and may produce a pinkish fluid. Gills that are infected may appear swollen and pale. In salt water fish, Monogeneans can infect the skin and gills, resulting in irritations to the host.
Heavy infections could result in erratic swimming behavior. Affected gills may become irritated and swollen. Monogenea are small parasitic flatworms mainly found on skin or gills of fish. A few species infecting certain marine fish are larger, and marine forms are generally larger than those found on freshwater hosts. Monogenea are often capable of dramatically elongating and shortening as they move. Biologists need to ensure that specimens are completely relaxed before measurements are taken.
Monogeneans lack respiratory, skeletal, and circulatory systems and have no or weakly developed oral suckers. They have a simple digestive system consisting of a mouth opening with a muscular pharynx and an intestine with no terminal opening anus. Monogenea are Platyhelminthes, so are among the lowest invertebrates to possess three embryonic germ layers—endoderm, mesoderm, and ectoderm.
In addition, they have a head region that contains concentrated sense organs and nervous tissue brain. Like all ectoparasites, monogeneans have well-developed attachment structures. The anterior structures are collectively termed the prohaptor , while the posterior ones are collectively termed the opisthaptor , or simply haptor.
The posterior opisthaptor with its hooks, anchors, clamps etc. Generally, monogeneans also are hermaphroditic with functional reproductive organs of both sexes occurring in one individual. Most species are oviparous, but a few are viviparous. The ancestors of Monogenea were probably free-living flatworms similar to modern Turbellaria. According to the more widely accepted view, "rhabdocoel turbellarians gave rise to monogeneans; these, in turn, gave rise to digeneans , from which the cestodes were derived.
Another view is that the rhabdocoel ancestor gave rise to two lines; one gave rise to monogeneans, which gave rise to digeneans, and the other line gave rise to cestodes". About 50 families and thousands of species are described. Some parasitologists divide the Monogenea into two or three subclasses based on the complexity of their haptor: the Monopisthocotylea have one main part to the haptor, often with hooks or a large attachment disc, whereas the Polyopisthocotylea have multiple parts to the haptor, typically clamps.
These groups are also known as Polyonchoinea and Heteronchoinea, respectively. Polyopisthocotyleans are almost exclusively gill-dwelling blood feeders, whereas monopisthocotyleans may live on the gills, skin, and fins. All of these can cause epizootics in freshwater fish when raised in aquaculture. Monogeneans possess the simplest lifecycle among the parasitic platyhelminths.
They have no intermediate hosts and are ectoparasitic on fish seldom in the urinary bladder and rectum of cold-blooded vertebrates.
Although they are hermaphrodites , the male reproductive system becomes functional before the female part. The eggs hatch releasing a heavily ciliated larval stage known as an oncomiracidium. The oncomiracidium has numerous posterior hooks and is generally the life stage responsible for transmission from host to host. No known monogeneans infect birds , but one Oculotrema hippopotami infects mammals , parasitizing the eye of the hippopotamus. From Wikipedia, the free encyclopedia.
Class of ectoparasitic flatworms. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Tubbsa et al. International Journal for Parasitology 35 , — Monogenean Parasites of Fish. Institute of Food and Agricultural Sciences. Parasite, 21, Fish diseases and parasites. Abergasilus Amoebic gill disease Anisakis Carp lice Ceratomyxa shasta Clinostomum marginatum Dactylogyrus vastator Diphyllobothrium Cymothoa exigua Eustrongylidosis Epizootic ulcerative syndrome Flukes Glugea Gyrodactylus salaris Henneguya zschokkei Ich freshwater Ich marine Kudoa thyrsites Lernaeocera branchialis Microsporidia Monogenea Myxobolus cerebralis Myxosporea Nanophyetus salmincola Pseudorhabdosynochus spp.
Diseases and parasites in cod Diseases and parasites in salmon Disease in ornamental fish List of aquarium diseases. Amnesic shellfish poisoning Brevetoxin Ciguatera Diarrheal shellfish poisoning Fish kill Marine viruses Neurotoxic shellfish poisoning Paralytic shellfish poisoning Saxitoxin. Categories : Monogenea Protostome classes. Hidden categories: Articles with short description Articles needing additional references from March All articles needing additional references Articles with 'species' microformats.
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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 reproductive structures. Some monogeneans are oviparous egg-laying and some are viviparous live-bearing.