PHYLUM NEMATODA

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PHYLUM NEMATODA

• Page 330-331

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Phylum Nematoda

• Second worm phylum
• More than flatworms
• Think of rubber tubing
• Invertebrates
• Tube-like body tapering to a point
• Roundworms found everywhere
• soil, freshwater, salt water, and in and on
  other organisms
• wet sand, forest soils, Antarctic sands, and
  even pools of super hot water

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Physical Characteristics

• Round, smooth, tube-like
• Pointed at both ends (taper to a point at each
  end)
• 2 body openings not one (more complex than
  flatworms)
• 2 openings to digestive system
• -anterior is the mouth
• -posterior is the anus

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• The digestive system is one continuous tube from
  mouth to anus (organs float in this tube)
• 5. cephalization

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Roundworms
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Cell Structure

• 3 cell layers
• 2. Organized cells, tissues, organs, and organ
  systems

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Locomotion

• Roundworms have a unique way of moving
• Have muscle tissue which runs lengthwise tip to
  tip
• As the muscle contract, the tail end and head end
  are pulled closer together
• Move like a whip

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Digestive System (Food Getting)

• Unlike flatworms have a body cavity and the
  organs move in the body cavity (not a true
  coelom)
• 2 body openings
• More efficient than the flatworm
• 3. Both free living and parasitic (parasites)

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Free living

• Role as decomposers in soil
• Digest dead matter and return useful material to
  soil
• 3 billion in a acre of topsoil

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Parasites

• Harmful and harmless
• Harmful
• -can cause millions of dollars of crop
  damage every year
• -hookworm and trichina worm
• (trichinosis)

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What is Trichinosis?

• Humans
• Eating pork or other meat that is infected
• Pigs take in through infected garbage
• Reproduce in intestines
• Larvae burrow in body of muscle tissue
• Get meat from pig and if not cooked well, the
  larvae will not be killed and transfers to the
  human
• Grows in the intestine
• Causes muscle pain, fever, weakness, and can lead
  to death if not treated

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Nervous and Reproductive System

• Nervous System simple
• Reproductive System
• 1. most are separate sexes
• 2. sexual reproduction transfer of egg and
  sperm
• No Respiratory and Circulatory System

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Examples

• size varies from microscopic to some parasites 1
  meter long
• 1. Ascaris free living and parasitic
• Trichina Worm parasite (trichinosis)
• 3. Hookworm - parasite

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Roundworms