? Monogenea
Dermophthirius, a microbothriidmonogenean parasitic on elasmobranchs
Scientific classification
Kingdom: Animalia Phylum: Platyhelminthes Class: Monogenea Carus, 1863

Monogenea (adj. monogenean) are a group of largely ectoparasitic members of the flatworm phylum Platyhelminthes. They are especially common on the skin, fins and gills of fishes and there are thousands of described and undescribed species. Less commonly, they can be found in the urinary bladder and rectum of cold-blooded vertebrates. None infect birds, but one (Oculotrema hippopotami) infects mammals, parasitizing the eye of a hippopotamus. They have direct life-cycles with no asexual reproduction (unlike the Digenea) and in those that lay eggs, a larval stage (generally ciliated) called an oncomiracidium that is responsible for transmission from host to host. As adults, they eat the blood, mucus, and epithelial cells of their host. Adults have both a prohaptor (for feeding) and an opisthaptor (for attachment). Image File history File links Download high resolution version (800x1229, 141 KB) A monogenean parasite of fishes. ... Superorders Galeomorpha Batoidea Selachimorpha Elasmobranchii is the subclass of cartilaginous fishes that includes skates, rays and sharks. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms (as opposed to folk taxonomy). ... Phyla Animals are a major group of organisms, classified as the kingdom Animalia or Meta­zoa. ... Classes Monogenea Trematoda Cestoda Turbellaria The flatworms (Platyhelminthes, Greek platy: flat; helminth: worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... Classes Monogenea Trematoda Cestoda Turbellaria The flatworms (Platyhelminthes, Greek platy: flat; helminth: worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... In aquatic organisms, gills are a respiratory organ for the extraction of oxygen from water and for the excretion of carbon dioxide. ... In the anatomy of mammals, the urinary bladder is the organ that collects urine excreted by the kidneys prior to disposal by urination. ... The posterior aspect of the rectum exposed by removing the lower part of the sacrum and the coccyx. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... For other meanings of bird, see bird (disambiguation). ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Binomial name Hippopotamus amphibius Linnaeus, 1758 The Hippopotamus (Hippopotamus amphibius a. ... Parasite life cycles can take a variety of forms, all involving the exploitation of one more hosts. ... Orders within the Digenea Strigeidida Azygiida Echinostomida Plagiorchiida Opisthorchiida The digenea (Gr. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Mucus is a slippery secretion of the lining of various membranes in the body (mucous membranes). ... In zootomy, epithelium is a tissue composed of a layer of cells. ...

Some parasitologists divide Monogenea into two subclasses based on the complexity of their haptor: Monopisthocotylea have one main part to the haptor, often with hooks or a large attachment disc, whereasPolyopisthocotylea 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.

Monopistocotylea include:

• Genus Gyrodactylus, which has no eyespots and is viviparous.
• Genus 'Dactylogyrus, which has four eyespots and lays eggs. This is one of the largest metazoan genera, with at least 970 species.
• Genus Neobenedenia, which is much larger and lives on the skin of many tropical marine species, causing problematic disease in marine aquaria.

All of which can cause epizootics in freshwater fish when raised in aquaculture. Neobenedenia - A genus of Monopisthocotylean monogenean flatworm parasites. ... An epizootic is the nonhuman equivalent of an epidemic, meaning that large numbers of animals are infected with a disease. ... The examples and perspective in this article may not represent a worldwide view. ...

Polyopisthocotylea include:

• Genus Diclidophora, which is primarily found in marine fish and primitive freshwater fish like sturgeons and paddlefish.