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WORM WEEK

PHYLUM NEMATODA. WORM WEEK. PHYLUM NEMATODA. Over 28,000 species have so far been described. Commonly referred to as the roundworms. Among the most abundant multicellular animals Mostly free-living Some are predators with teeth and other

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WORM WEEK

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  1. PHYLUM NEMATODA WORM WEEK

  2. PHYLUM NEMATODA • Over 28,000 species have so far been described. • Commonly referred to as the roundworms. • Among the most abundant multicellular animals • Mostly free-living • Some are predators with teeth and other • mouthparts, many are scavengers or parasites.

  3. Source of picture: http://nematology.ifas.ufl.edu/nguyen/flnem/idnema.htm nematodes

  4. Body Cavity Pseudocoelomate (pseudo=false),because they do not have a true coelom. This means that they do have the peritoneal cavity ( or gut), but it is not lined with mesoderm.

  5. Source of picture: http://www.biog1105-1106.org/labs/inverts/nematoda.html

  6. Digestive System • Complete digestive tract with specialized regions – Anterior mouth – Muscular pharynx (esophagus) – Long, straight midgut (intestine) – Ventral anus No internal transport system - breathe and excrete metabolic wastes through skin

  7. Nervous System • Very simple • nerve transmit sensory information and control movement • Cerebral ganglion (“brain”) – Anterior • Two main longitudinal ganglial chords – Dorsal – Ventral

  8. Locomotion • side to-side movement only

  9. Skeletal Type • fluid in pseudocoelom serves as hydrostatic skeleton

  10. Reproduction • Nematodes are sexual animals The male is generally slightly smaller than the female, which usually displays a bent Tail .

  11. Ascaris lifecycle • Pg 577

  12. Life Cycle of A.lumbricoides • Eggs hatch in the intestine • Larvae migrate to the liver, then to the blood, • then to lungs, pharynx, and back to the • intestine • Mature and mate in the intestine • Eggs are released with the feces • Ingestion leads to infection of the next host

  13. A female Ascaris can produce 27 million eggs Ascaris egg nematodes

  14. Source of picture: http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookdiversity_7.html nematodes and annelides

  15. Ascaris lumbricoides( Human roundworms) • Simple life cycle with one host • The host is humans or a few other mammals • (endoparasite). • Infection comes from ingesting eggs • Ascarids are the largest nematodes nematodes and annelides

  16. Other roundworm parasitesHookworms • Survive on the blood of host

  17. Other roundworm parasitesFilarial worms • Elephantiasis, a disease of humans, is restricted to tropica areas and is caused by a filarial worm Brugia malayi that utilizes a mosquito as a secondary host. • Adult worms reside in lymphatic vessels, collection of fluid is impeded, and the limbs of an infected person may swell to a monstrous size.

  18. Source of picture: http://www.infahealth.com/health-medicine/disease-elephantiasis-filariasis/

  19. Other roundworm parasitesTrichinella • Causes trichinosis. Larvae travel from the intestines through the blood then burrow into organs and tissues forming cysts. • Infected tissues are eaten (uncooked pork)

  20. Nematoda : Trichinella sp. nematodes and annelides

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