Editing Monogenea (section)

==Ecology and lifecycle==
[[File:Parasite130103-fig1 Protopolystoma xenopodis (Monogenea, Polystomatidae) egg.tif|thumb|left|Eggs of the monogenean ''[[Protopolystoma xenopodis]]'',<ref>Theunissen, M., Tiedt, L. & Du Preez, L. H. 2014: The morphology and attachment of ''Protopolystoma xenopodis'' (Monogenea: Polystomatidae) infecting the African clawed frog ''Xenopus laevis''. Parasite, 21, 20. {{doi|10.1051/parasite/2014020}}</ref> a parasite of the African clawed frog ''[[Xenopus laevis]]]]
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 [[Poikilotherm|cold-blooded]] [[vertebrates]]).  Although they are [[hermaphrodite]]s, 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.<br />
No known monogeneans infect [[birds]], but one (''[[Oculotrema hippopotami]]'') infects [[mammals]], parasitizing the eye of the [[hippopotamus]].