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HELMINTHES

HELMINTHES. Characteristics: Traditionally classified in Kingdom Animalia, now in Domain Eucarya Super Group Opisthokonta Eucaryotic Multicellular Chemoorganotrophic. Worms may be "free living" or "parasitic” Obligate parasites - they cannot complete their lifecycle without a host(s)

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HELMINTHES

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  1. HELMINTHES Characteristics: Traditionally classified in Kingdom Animalia, now in Domain Eucarya Super Group Opisthokonta Eucaryotic Multicellular Chemoorganotrophic

  2. Worms may be "free living" or "parasitic” Obligate parasites - they cannot complete their lifecycle without a host(s) Facultative - they may be parasitic but can also survive as free-living Considered as endoparasites or ectoparasites

  3. Factors in parasitology: • do not usually kill their host • evolve elaborate cycles of reproduction • high rate of reproduction • complex life cycles involving 1 or more hosts - usually host specific • development of specialized structures (hooks, suckers, etc.) • ability to fight immune system (production of enzymes, changing antigens, other disguises) • loss of structures (eyes, locomotion, etc.)

  4. Classification – Super Group Opisthokonta: • Phylum Platyhelminthes – “Flat Worms” • most primitive • dorsoventrally flat • nonsegmented • acoelomic - no body cavity • incomplete digestive tract • free-living and parasitic • hermaphroditic except blood flukes • sexual and asexual reproduction • ability to regenerate

  5. Class Trematoda- "Flukes" • From lab - Fasciola hepatica, Clonorchis sinenesis, Schistosoma • oral and ventral suckers which function to attach and aid in locomotion • surrounded by integument whose surface contains spines and projections • all flukes are parasitic as adults • utilize snails as their first intermediate host • produce operculated eggs which are eggs that have an operculum, or lid

  6. Specific stages as larvae: miracidium sporocyst redia cercaria metacercaria

  7. Lifecycle of the blood flukes - Schistosoma japonicum, S. mansoni, S. haematobium, S. intercalatum, S. mekongi

  8. Lifecycle of liver fluke - Clonorchis sinensis

  9. Class Cestoda - "Tapeworms" From lab - Taenia, Dipylidium all are parasitic - endoparasites, usually in the digestive tract have an attachment organ - scolex which has hooks on a rostellum and suckers next is a neck followed by “segments,” or sections called proglottids containing reproductive organs which become more mature towards the end of the worm the "body" is referred to as a strobila

  10. produce operculated ova like the flukes feed by absorbing nutrients through the body wall an adult cestode can range from 0.02 to 10 meters different species of tapeworms infect different hosts, many are host specific and will not infect other org outside the host, others will

  11. Lifecycle of Taenia soliumincluding cysticercosis

  12. Phylum Nematoda - “Unsegmented Roundworms” • From lab - Wuchereria bancrofti, Trichinella spiralis, Enterobius vermicularis, Ascaris lumbricoides, Necator americanus • unsegmented, cylindrical, long and slender • complete digestive system • pseudocoelomic: false body cavity - not lined with tissue derived from mesoderm • separate sexes • body is covered by a cuticle with ridges, striations or wart-like structures

  13. Lifecycle of Enterobius vermicularis

  14. Lifecycle of Ascaris lumbricoides

  15. Lifecycle of Necator americanus

  16. Lifecycle of Trichinella spiralis

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