The Worms

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The Worms

• Phylum Platyhelminthes
• Phylum Nemertea
• Phylum Nematoda
• Phylum Annelida

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Bilateral Symmetry

• One way to cut and get 2 identical halves
• Front (anterior) and rear (posterior)
• Back (dorsal) and belly (ventral)
• More active in pursuit of prey

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Platyhelminthes - Flatworms

• Dorsoventrally flattened
• Simple Central Nervous system
• Muscular system, Reproductive system - True
  organs
• Singular opening for gut

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20,000 Species of Flatworms

• Turbellarians - Free-living carnivores, seen most
  in marine habitats
• Flukes (Trematodes) largest group, parasites
• Tapeworms (cestodes) live in intestines.

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Ribbon Worms (Nemertea)

• Sac Gut digestive tract (mouth, gut)
• Circulatory system/Hermaphrodites
• Proboscis used to entangle prey
• Feed on worms and crustaceans

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Nematodes (some roundworms)

• Live in sediment or tissues of marine organisms
  (parasitic)
• Cylindrical body, pointed at both ends.
• Larva found in the flesh of many fish
• Infection of humans from eating raw or under
  cooked fish

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Annelida segmented worms

• Includes earthworms and many marine worms
• Polychaetes marine annelids.
• Each segment has parpodia with setae at the ends.
• Closed circulatory system
• Most carnivores - Nereis

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More Annelids

• Oligochaetes
• Marine earthworms, found in mud and sand
• Leeches (Hirudinea)
• Most are freshwater sucker at ends

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Tube worm
Beard Worm
Arrow Worm
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Brachiopoda (not a worm)

• Lamp shell
• Two valves, dorsal and ventral
• Lophophore, unique feeding structure like two
  ciliated, coiled arms

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The Christmas Tree Worm
The Christmas tree worm, Spirobranchus giganteus,
is a Christmas tree-shaped serpulid tube-dwelling
worm with magnificent twin spirals of plumes used
for feeding and respiration. This cone-shaped
worm is one of the most widely recognized
sedentary polychaete worms.