NEMATODA

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NEMATODA
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Characteristics

• Roundworms
• Name means thread-like
• Thought to be most abundant animals on Earth
  (only about 20,000 species identified, thought
  that there might be more than 1,000,000)
• Bilateral symmetry
• Size- all under 5mm

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Anatomy

• Long narrow bodies no legs
• Pseudocoelomates
• Mouth and Anus!
• Excretion out of anus
• Outer covering called cuticle is shed as worm
  grows usually 4 times during lifetime

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Anatomy

• No respiratory or circulatory systems
• No skeleton
• Two nerve cords
• Has muscles

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Feeding

• Herbivores
• Bacterivores
• Fungivores
• Predators
• Omnivores
• Parasites picture is of Trichinella in pork meat

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Trichinella spiralis

• Found in pork meat that is undercooked
• Symptoms nausea, diarrhea, muscle pain as worms
  invade, cardiac problems, pneumonia, nervous
  disorders
• No cure

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Pinworms

• Intestinal worms- live in rectum of humans
• Female worms leave rectum at night to lay eggs on
  surrounding skin
• Eggs can survive in bedding and clothing for 2
  weeks
• Spread by ingesting eggs
• Medicines kill worms - curable

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Ascaris lumbricoides

• Intestinal roundworm
• Female worm can produce up to 200,000 eggs a day
• Eggs ingested from food contaminated with fecal
  matter
• Larvae hatch, burrow through intestine, can
  migrate anywhere in body
• Medicines kill worms - curable

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Reproduction

• Reproduce sexually
• Both males and females
• Usually males smaller in size than females

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Habitat

• Mostly found in soils
• Can be found at bottom of deepest oceans to tops
  of highest mountains
• Found in tropics to polar regions
• Everywhere on Earth
• Some free-living, some parasites
• What are some biotic and abiotic factors?

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Adaptations

• Parasites are wide-range can infect many hosts
• Nematodes have a metabolically- suppressed stage
  if survival is threatened
• During drought they go into dormancy (like
  hibernation)