Phylum nematoda chapter 27 2
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Phylum Nematoda (Chapter 27.2). Please set up your notebook for Cornell Notes. Nematodes Characteristics Slender, unsegmented w/ tapered ends Range from microscopic to 1 meter ling Most are free-living, some are parasitic Develop from three germ layers

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Phylum Nematoda (Chapter 27.2)

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Phylum nematoda chapter 27 2

Phylum Nematoda (Chapter 27.2)

Please set up your notebook for Cornell Notes


Phylum nematoda chapter 27 2

Nematodes

  • Characteristics

    • Slender, unsegmented w/ tapered ends

    • Range from microscopic to 1 meter ling

    • Most are free-living, some are parasitic

    • Develop from three germ layers

      • Have a body cavity b/w endoderm and mesoderm

        • Pseudocoelomate

    • Have a digestive tract with two openings


Phylum nematoda chapter 27 2

  • Form and function

    • Feeding

      • Free living worms are predators with grasping mouth parts

      • Soil dwelling and aquatic forms eat algae, fungi or decaying organic matter

    • Respiration, Circulation and Excretion

      • These processes take place by diffusion


Phylum nematoda chapter 27 2

  • Response

    • Simple nervous system with several ganglia

    • Numerous sense organs

  • Movement

    • Nematodes have muscles that extend the length of the body

    • Use the pseudocoelom and a hydrostatic skeleton


Phylum nematoda chapter 27 2

  • Reproduction

    • Separate male and female organisms

    • Reproduce sexually using internal fertilization

    • Parasitic roundworms have life cycles that involve two or three host or multiple organs in one host


Phylum nematoda chapter 27 2

  • Roundworms and Human Disease

    • Trichinosis  caused by Trichinella

      • Mate in intestines of host, larva are released into the blood stream to take up residence in various organs, become inactive cysts in muscles cells

      • Extremely painful

      • Common hosts are pigs and rats

        • Human contract by eating undercooked, infected pork


Phylum nematoda chapter 27 2

  • Filarial worms  threadlike worms that live in blood and lymph vessels of birds and mammals

    • Transmitted by biting insects

    • Cause elephantitis extreme swelling by to buildup of fluid


Phylum nematoda chapter 27 2

  • Ascarid worms

    • Ascarislumbricoides

      • Mature in intestine and release eggs in feces

      • Feces can contaminate food or water continuing cycle

      • Causes malnutrition


Phylum nematoda chapter 27 2

  • Hookworms  soil dwelling

    • Lay eggs in soil

    • Pierce feet to burrow into skin and enter blood stream

    • Consume blood causing weakness and poor growth


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