ZOO 115 Invertebrate Zoology

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ZOO 115 Invertebrate Zoology

• Nematoda

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Phylum Nematoda

• Common name round worms
• gt20,000 species.
• Mostly widespread and abundant of all metazoans
• 90,000 worms in a decomposing apple.
• Marine and freshwater benthos, soil, parasites on
  plants and animals

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Phylum Nematoda - Anatomy

• Most freeliving lt2.5 mm in length. Some
  parasites gt 50 cm in length.
• Body is cylindrical with a pseudocoel

• Complex cuticle
• Must molt (Ecdysis)
• Anterior end is radially symmetrical but the rest
  of the body has bilateral symmetry

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Phylum Nematoda - Head RegionNervous system
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Phylum Nematoda - Head Region

• 3-6 lips at the mouth

• Buccal Cavity varies depending on prey
• Bacteria - no teeth or stylet
• Plant root - stylet
• Carnivore - small teeth and sometimes stylet
• Intestine - large hook-like teeth

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Phylum Nematoda - Digestive tract
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Phylum Nematoda Excretion

• Excretory glands and canals thought to be
  involved in
• Osmoregulation
• Ionic regulation
• Excretion of waste metabolites
• Ammonia secreted through body wall

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Phylum Nematoda Musculature

• Longitudinal muscles only!

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Phylum Nematoda - Reproduction

• Separate sexes - usually
• Males have hook-like posterior
• Testis
• Male Rectum - Cloaca
• Reproduction
• Digestive waste
• Spicule for sperm transfer
• Retractable

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Phylum Nematoda - Reproduction

• Females
• Ovaries
• Eggs
• Vulva
• Seminal Receptacle

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Phylum Nematoda - Parasites Roundworm Life Cycles
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Phylum Nematoda - Parasites Hookworm
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Phylum Nematoda - Parasites Trichinella
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Phylum Nematoda - Parasites Filariasis