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Phylum Nematoda

Phylum Nematoda. The Roundworms. Phylum Level Characteristics. round, not flattened no segmentation complete digestive system (2 openings: mouth and anus) -soft bodied, hydrostatic skeleton -bilateral symmetry No circulatory system Nutrients and wastes diffuse through body cells.

ralph-travis
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Phylum Nematoda

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  1. Phylum Nematoda The Roundworms

  2. Phylum Level Characteristics • round, not flattened • no segmentation • complete digestive system • (2 openings: mouth and anus) • -soft bodied, hydrostatic skeleton • -bilateral symmetry • No circulatory system • Nutrients and wastes diffuse through body cells

  3. Nervous System • Exhibit cephalization as they have a “head” end • In head are several ganglia or nerve bundles, no real “brain” • Have sense organs that detect chemicals given off by prey or hosts • Longitudinal muscles so movement is “snake-like”

  4. Reproduction • Sexual • Most species have separate males and females, a few are hermaphroditic • Fertilization occurs within the female • Parasitic life cycles can involve many hosts

  5. Diversity • most are free-living • found in all habitats • very successful (high # of species and large #’s of them)

  6. Diversity • parasitic round worms also infect most kinds of animals and plants • -i.e. Ascaris infects humans

  7. Ascaris Life Cycle • Adult worms live in intestines • Produce many eggs that leave in hosts feces • Feces contaminated food or water eaten by another host • Eggs hatch in intestine of new host • Young worms burrow into the walls of the intestine and enter surrounding blood vessels • Carried by blood, worms end up in lungs • Travel up air passage into throat then are swallowed • Carried back to intestines where process begins again! ascaris animation

  8. Diversity • -i.e. hookworm can enter body through bare feet

  9. Hookworm Life Cycle • Hookworm eggs hatch and develop in soil • Use sharp teeth and hooks to burrow into feet • Continue burrowing until they enter the bloodstream • Travel to lungs, coughed up and swallowed to eventually reach intestines • Adult worms dig into intestinal wall and suck blood of host http://www.youtube.com/watch?v=tGHAlmCj3DM

  10. Assignment: • Watch Nematoda video • Complete nematoda worksheet • Complete nematoda flash cards! Please remind me that we need to catch up on the “ecological significance” notes for the last 2 phyla!!

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