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The Worms - PowerPoint PPT Presentation
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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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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
- Dorsoventrally flattened
- Simple Central Nervous system
- Muscular system, Reproductive system - True organs
- Singular opening for gut
20,000 Species of Flatworms
- Turbellarians - Free-living carnivores, seen most in marine habitats
- Flukes (Trematodes) – largest group, parasites
- Tapeworms (cestodes) – live in intestines.
Ribbon Worms (Nemertea)
- Sac Gut digestive tract (mouth, gut)
- Circulatory system/Hermaphrodites
- Proboscis – used to entangle prey
- Feed on worms and crustaceans
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
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
More Annelids
- Oligochaetes
- Marine earthworms, found in mud and sand
- Leeches (Hirudinea)
- Most are freshwater – sucker at ends
Brachiopoda (not a worm)
- Lamp shell
- Two valves, dorsal and ventral
- Lophophore, unique feeding structure – like two ciliated, coiled arms
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.
