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MARINE WORMS. Common Characteristics of All Worm Phyla Hydrostatic skeleton Bilateral symmetry.

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Presentation on theme: "MARINE WORMS. Common Characteristics of All Worm Phyla Hydrostatic skeleton Bilateral symmetry."— Presentation transcript:

1 MARINE WORMS

2 Common Characteristics of All Worm Phyla Hydrostatic skeleton Bilateral symmetry

3 Phylum Platyhelminthes - Flatworms Dorsoventrally flattened – flat backs and bellies Have real organs and organ systems Ladderlike nerve cord with a simple brain Saclike digestive system (only one opening) 15,000 species –Turbellarians – mostly free swimming carnivores –Flukes (trematodes) – all are parasites –Tapeworms (cestodes) – parasites with long segmented bodies

4 Phylum Nemertea – Ribbon Worms Long flattened bodies Complete digestive tract (separate mouth and anus) Circulatory system with blood Proboscis – long fleshy tube used to entangle prey 900 species, mostly marine

5 Phylum Nematoda - Roundworms Common in sediments or as parasites Cylindrical body typically pointed at both ends Complete digestive tract 10,000-15,000 species but many could yet to be discovered

6 Phylum Annelida – Segmented worms 13,000 species Complete digestive tract Efficient crawlers and burrowers Closed circulatory system – blood always remains in blood vessels (arteries, veins, capillaries) Class Polychaeta –On each segment they have a pair of parapodia and setae (bristles) –Gills for respiration –6000 species almost entirely marine

7 –4 to 10 cm in length –Deposit or suspension feeders –Some are tube dwelling Class Hirudinea – Leeches –Mostly freshwater –Suckers at each end –No parapodia

8 Other Marine Worms Phylum Sipuncula – Peanut worms –Peanut shaped, deposit feeders Phylum Echiura –Sausage shape, buried in mud Phylum Pogonophora – Beard Worms –Lack a digestive system, symbiotic relationship with bacteria for obtaining nutrients Vestimentiferans found at hydrothermal vents Phylum Chaetognatha – Arrow Worms –60 species, but common in plankton, fishlike body, voracious carnivores


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