10/16/20111•Protozoa:» Single Celled Organisms» Eukaryotic•Platyhelminthes -Flatworms–Trematodes, Cestodes-•Nematodes– Roundworms•ArthropodsCestodes•Phylum Platyhelminthes (flatworms)–Class Trematoda (flukes)–Class Cestoidea (tapeworms)Lack a mouth anddigestive tract.– Subclass Eucestoda (true tapeworms)– Order Pseudophyllidea» GenusDiphyllobothrium,– Order Cyclophyllidea» Genera:Taenia, Hymenolepis, Dipylidium
10/16/20112General CharacteristicsMorphology•Multi-segmented and up to25m long.•Scolex- at anterior endfunctions in attachment•Neck- narrowest part of theworm•Strobila-made up of segmentsof the worm calledproglottids.
10/16/20113Scolex•Acetabulate-has foursuckers or muscular cups.May have an armedrostellum.Bothriate -two, four orsix longitudinallyarranged shallowdepressions
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10/16/20115Tegument•Lined with microvilli– Glycocalyx–Microthrices (microthrix)•Nutrient absorption•Tegumental andparenchymal musculature –circular and longitudinalmuscles•Parenchyma-spaceenclosed by tegument•Cestodes have a well developednervous system.A ‘brain’ in scolex is connected via nerves to thestrobila. Reproductive organs and musculature inproglottids are extensively innervated.•Osmoregulatory and excretory system- collectingcanals (ventral from scolex; dorsal to scolex)
10/16/20116Reproductive System•Proglottid has male andfemale organs•Proglottids on the sameworm or another wormcan engage in mating.•Anapolyticworms(Diphyllibothrium) tannedeggs exit through uterinepore.•Apolyticworms – entiregravid proglottid isreleased – no uterine pore(Dipylidium)Egg•Egg is encased in a shell• Layered–outer envelope– embryophore–inner envelope–oncosphere - embryo isequipped with hooks andwill give rise to larvalform. Contain vittelinecells as food source
10/16/20117•Pseudophyllideaneggs aretanned, have a ciliatedembryophore and have anoperculum at one end. Fromwithin the oncosphere acoracidiumemerges (seen inDiphyllobothrium latum).•Dipylideaneggs are thin shelled,have a relatively thick outerenvelope and a non-ciliatedembryophore (DipylidiumandHymenolepis).•Taenoideggs lack shell and outerenvelope. Embryophore isoutermost covering (TaeniaandEchinococcus).Life Cycle PatternsPseudophyllidean pattern•Eggs released through uterine poreare expelled in feces.•Coracidia emerge and swim aroundin water.