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The Worms

The Worms. Phylum Platyhelminthes Phylum Nemertea Phylum Nematoda Phylum Annelida. 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. Platyhelminthes - Flatworms.

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The Worms

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  1. The Worms Phylum Platyhelminthes Phylum Nemertea Phylum Nematoda Phylum Annelida

  2. 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

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

  4. 20,000 Species of Flatworms • Turbellarians - Free-living carnivores, seen most in marine habitats • Flukes (Trematodes) – largest group, parasites • Tapeworms (cestodes) – live in intestines.

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

  6. 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

  7. 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

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

  9. Tube worm Beard Worm Arrow Worm

  10. Brachiopoda (not a worm) • Lamp shell • Two valves, dorsal and ventral • Lophophore, unique feeding structure – like two ciliated, coiled arms

  11. 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.

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