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Roundworms (Phylum Nematoda)

Roundworms (Phylum Nematoda). Features. Bilateral symmetry and 3 cell layers Plus a “pseudocoelom” (fluid filled space betwen the mesoderm and internal organs) Have a complete (one-way) digestive tract (mouth – anus) Mostly free living, but some are parasitic

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Roundworms (Phylum Nematoda)

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  1. Roundworms (Phylum Nematoda)

  2. Features • Bilateral symmetry and 3 cell layers • Plus a “pseudocoelom” (fluid filled space betwen the mesoderm and internal organs) • Have a complete (one-way) digestive tract (mouth – anus) • Mostly free living, but some are parasitic • Can be anywhere from very tiny microscopic to 1 m in length!

  3. Form and function • Digestion: • Called an “intestine”, not a gastrovascular cavity (remember, this one is one way) • Respiration and circulation: • No organised system. O2 and CO2 diffuse through the skin • Excretory system: • 2 excretory canals with pores (openings) near anterior end

  4. http://www.biologie.uni-hamburg.de/b-online/library/onlinebio/BioBookDiversity_7.htmlhttp://www.biologie.uni-hamburg.de/b-online/library/onlinebio/BioBookDiversity_7.html

  5. Nervous system: • Head, dorsal and ventral nerves • Musculoskeletal system: • Longitudinal muscles only • Reproductive: • Sexual reproduction only • Seperate sexes and females are usually larger

  6. Ecology of unsegmented worms • Free living flatworms and roundworms are usually small and don't affect humans much • We pay more attention to the parasitic ones, which cause many horrific diseases

  7. Roundworm Parasites • Ascaris Video! • Hookworm • Filaria worm (elephantitis) • Trichinella (trichinosis) undercooked pork • Eye worms

  8. Ascaris lumbricoidesLife cycle(pg )lives in the intestine of the human after consuming undercooked meat/pok

  9. Hookworm infection • Baby worms burrow through soles of feet! • Larva cause massive damage when they migrate from lungs to the intestine

  10. Filaria worm • Transferred by mosquito • Block lymph capillaries and causes elephantitis

  11. Guinea worm • Roll it with a pin to pull it out of the flesh

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