Helminths > Trematodes > Class Trematoda

CLASS-TREMATODES from bhushan in this class of phy helminths is unsegmented,flat,broad,resembling leaf of tree or flatfish. termatode name from they having large prominent suckers with ahole in middle (trema-hole, tode-appearance). Subclass digenea require two hosts.for definitive hosts in which they pass the sexual or adult stage r mammanls, & intermediate host in which they pass their asexual or larval stages r freshwater molluscs,snails.

FLUKES They r hermaphroditic except for schistosomesin which sex is separate. Conspicuous feature is presence of two muscular cup-shaped sucker hence called distomata. one is oral sucker & other is ventral sucker or acetabulum.

cont… No body cavity,circulatory or respiratory organs. Alimentary canal appears Y – shaped. anus is absent. Excretory system consist of flame cell & collecting tubules. Rudimentary nervous system consisting of paired ganglion cell. Reproductive sys. Is well develop.

cont…. All flukes parasites live in s.intestine of man, except-----gastrodiscoides hominis. which live in L.intestine of man. Largest trematode which infecting man is fasicolopsis buski. Smallest is heterophyes. All trematode is oviparous & lay eggs which r operculated .except in case of schistosomes.

Larva Miracidium (miracidium—a little boy.) it is motile & ciliated. infects to the intermediate host snail. Sprocyst:-becomes the sac–like sporocyst. Within sporocyst, certain cell proliferate to form the germ balls,which r responsible for asexual replication. In schistosmes the sporocyst develops into second generation sporocyst in which infective larvae cercriae r formed by sexual multiplication.

cont.. Redia Cercariae (kerkos—tail) it is tale larvae. In live in fish ( sec.intermediat host).in case of schistosmes it is infective stage which penetrated directly skin of definite host. Metacercariae:- it is infective stage for definitive host

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