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Presentation on theme: "MARINE WORMS."— Presentation transcript:


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 Class Hirudinea – Leeches
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 Phylum Echiura
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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