Flatworms

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Flatworms Phylum Platyhelminthes
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Flatworms
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Phylum Platyhelminthes

• Characteristics
• Marine, freshwater, and terrestrial
• Flat, solid-bodied worms
• Bilateral symmetry
• Gastrovascular cavity
• One body opening

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Flatworm Organ Systems
Pharynx
Digestive System
GastrovascularCavity
Excretory Canal
Excretory Pore
Excretory System
Nervous System
Nerve Cord
Brain
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Class Turbellaria

• - planarians
• - free-living

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Class Trematoda

• - flukes
• - parasites

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RoundwormsPhylum Nematoda

• Characteristics
• Aquatic and terrestrial, very numerous
• Slender, thread-like worms
• Bilateral symmetry
• Complete digestive tract
• Two body openings

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BryozoansPhylum Ectoprocta
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Phylum Annelida Segmented Worms

• Characteristics
• Aquatic, terrestrial, or parasitic
• Bilateral symmetry
• Segmented body
• Well developed organ systems
• Closed circulatory system

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Annelids

• Class Polychaeta - mostly marine worms, such as
  Nereis (the clamworm)
• Class Hirudinea - the leeches (predominantly
  freshwater), such as Hirudo
• Class Oligochaeta - mostly freshwater and
  terrestrial worms, such as Lumbricus (the
  earthworms)

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Class Polychaeta

• - marine worms

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Proboscis WormsPhylum Rhynchocoela

• Characteristics
• Marine
• Ribbon-like worms
• Protrusive throat with piercing jaws

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RotifersPhylum Rotifera

• Characteristics
• Aquatic, free living, microscopic
• Wheel animals
• Bilateral symmetry
• Well developed organ systems

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RotifersPhylum Rotifera
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Proboscis WormsPhylum Rhynchocoela